LUBRICATION GEARS INTRODUCTION
T h e u s e of of g e a r s f o r p o w e r t r a n s m i s s i o n dates back several hundred years. Before the age of iron and steel, ge ars consisted of cir c u l a r w o o de de n w h e e l s i t h w o o d en en p e g s f a s t e n e d t o t h e r i m s t o s e r v e a s t e e th t h . T h e p o w e r u se se d in operating these mechanisms was provided either by ma n, animal, wa ter or wind. W ear was not too much of a problem with the crude wood-tooth gears, but later, when cast iron gears came into usage, some form of lubricat io io n b e c a m e n e c e s s a r y ; l u b r i c a t i o n a l s o r e d u c e d some of the noise. I n t h o se se e a r l y d a y s i t w a s k n o w n t h a t g r e a s y m a t e r i a l w o u ld ld r e d u c e n o is is e. e. A n i m a l f t s were about the only lubricants available, so they werc used. They served the purpose satisf a c t o r i l y b e ca ca u s e s p e e d s a n d l o a d s w e r e l ow ow a n d mechanical wear on the teeth was not too serious. Broken teeth could be replaced without too much trouble. However, by the time th e steam engine was invented, ge ars were ma de of iron, which would withstand greater loads and speeds. Later, as t h e m a c h i n e a g e c o n t i n u e d t o d e ve ve lo lo p , g e a r s o greater precision were required. At first spur a n d s t r a i g h t b e ve ve l g e a r s w e r e s a t i s f a c t o r y , b u t with the advent of the ste am tu rbin e and elec tric motor, gear design became more of a s c ie ie n ce c e a n d t h e h e r r in in g b o n e t y p e w a s p e r f e c t e d . T h e n t h e p r o c e s s of of g e a r c u t t i n g r e a l ly ly b e c a m e a n a t b e ca c a u se se p r e c is is i on on a n d s t r e n g t h f m e t a l
panied the development of automotive transportation and built-in transmission units involved the helical, spiral bevel and worm. They p a ve v e d t h e w a y f o r t h e h yp y p o id id g e a r w h i c h i s v i r tu tu a l l y s t a n d a r d i n a u t o m o t i v e e q u ip ip m e n t today. The objectives of the designers were smooth running, quiet meshing and uniform h a r d n e s s f t h e g e a r t e e th th t o w i t h s t a n d w e a r . T h e s e o b j e c t i v e s o n ly ly c a n b e a s s u r e d , h o w e v e r , with effective lubrication. Modern industry today demands greater p o w e r a n d s p ee ee d t h a n e v e r b e f o r e t o s a t i s f the increasing demand for m ore and m ore production. At the same time the turbines and engines that produce this power require gears that have greater toughness and higher precision than ever before. Only then can power be transmitted dependably into useful channels. This question of gear tooth structure is all the more important due to the common practice of deliberately overloading gears two or t h r e e t i m e s b ey e y o n d t h e i r r a t e d c a p a c i ty ty i n o r d e r to increase production. This demand for everi n c r e a s i n g p r o d u c t io i o n h a s pl pl a ce ce d a h e a v i e r l o a on the gears than perhaps on any other type o mechanism. Obviously, overloading in this manner will shorten th e life f t he ge ars, although it can be counteracted to a certain extent, but not completely, by the use of heavy-duty-type lubricants. The increased cost of gear replacement
TYPES
GEARS
Figures an show illustrations and brief descriptions of the nine basic types of of gear s which ar e found in industr ial use today, namely: Spur Spiral Be Beve ve Herringbone Rack Rack and Pinion Interna l Spur and Pinion Worm Str ai gh t Bevel Bevel Helical Helical Hypoid Spur Gear
&s pu r gea r is a cylinder, wheel, or disk on on the surfa ce f which are cut parallel teeth, each in a common plane with the axis. Spur gears are most commonly found on industrial machines, working under ordinary conditions conditions,, a t moderate speeds speeds and with medium pressures exerted upon the teeth. There a re also several spec special ialize ized d variati ons of of the s pur gear, such as eliptical gears, which impart a rhythmic motion to the driven shaft, and intermittent gears, in which the driver and driven ge ars have corresponding blank spaces spaces where th e motio f t he driven gea r stops momentarily. Rack and Pinion Gear
This is a specializ specialized ed form of of spu r gear where the s pur meshe with gear teeth on a flat rack. The function of this device is to bring about a reciprocating motion. Helical Gear
The helical gear resembles the spur gear in that the teeth are cut on a cylindrical body, but it differs from the spur gear in that the teeth a re spiraled spiraled around the body, body, rat her than formed formed parallel parallel t o the axis of th e gear body body.. Sp iralin g the teeth provide provide smoothness of operation. Herringbone Gear
The herringbone gear resembles the helical gears having reversed directi ons of of spiral , place placed d side by side, so th at the tee th come together to form a chevron pattern. In general, helical or herringbone gears are used with parallel shafts. In the herringbone design, spiraling the teeth in both directions neutralizes end thrust. Herringbone gearing is generally used in enclosed drives, where fluid lubricants can be employed. Straight Bevel Gear
The teeth of of the str aigh t beve bevell gear a re cut on on an angular surface such as would be represented by a truncated cone. This
TYPES
GEARS
Figures an show illustrations and brief descriptions of the nine basic types of of gear s which ar e found in industr ial use today, namely: Spur Spiral Be Beve ve Herringbone Rack Rack and Pinion Interna l Spur and Pinion Worm Str ai gh t Bevel Bevel Helical Helical Hypoid Spur Gear
&s pu r gea r is a cylinder, wheel, or disk on on the surfa ce f which are cut parallel teeth, each in a common plane with the axis. Spur gears are most commonly found on industrial machines, working under ordinary conditions conditions,, a t moderate speeds speeds and with medium pressures exerted upon the teeth. There a re also several spec special ialize ized d variati ons of of the s pur gear, such as eliptical gears, which impart a rhythmic motion to the driven shaft, and intermittent gears, in which the driver and driven ge ars have corresponding blank spaces spaces where th e motio f t he driven gea r stops momentarily. Rack and Pinion Gear
This is a specializ specialized ed form of of spu r gear where the s pur meshe with gear teeth on a flat rack. The function of this device is to bring about a reciprocating motion. Helical Gear
The helical gear resembles the spur gear in that the teeth are cut on a cylindrical body, but it differs from the spur gear in that the teeth a re spiraled spiraled around the body, body, rat her than formed formed parallel parallel t o the axis of th e gear body body.. Sp iralin g the teeth provide provide smoothness of operation. Herringbone Gear
The herringbone gear resembles the helical gears having reversed directi ons of of spiral , place placed d side by side, so th at the tee th come together to form a chevron pattern. In general, helical or herringbone gears are used with parallel shafts. In the herringbone design, spiraling the teeth in both directions neutralizes end thrust. Herringbone gearing is generally used in enclosed drives, where fluid lubricants can be employed. Straight Bevel Gear
The teeth of of the str aigh t beve bevell gear a re cut on on an angular surface such as would be represented by a truncated cone. This
TYPES (FIGURE
GEARS continued
This gear is also adaptable to non-parallel shafting. It ap proaches tne a ppearan ce f t he st raig ht spiral type of of tooth. lnternal Spur Gear and Pinion
The annular gear ha s paralle parallell teeth similar similar to the spur ge ar but cut on the inside rim of t he ri ng. T he companion pinion, how ever, is a standard gear. The main driving element on certain types of tra ct ors is a typical example of of t he use of of g ears of this type. Worm Gear
This figure shows the two members of a worm gear set which are ltnown ltnown as the worm and the worm wheel, wheel, or gear. The worm resembles a screw, although it is really a special form of helical gear, and its teeth are referred to as threads. The worm is usually made of a hard, wear-resistant steel; the worm wheel, which resembles a helical gear (except that it is throated, or curved on the face to envelop the worm partially), is prefer abl y made of of a gr ad e of of bronze having good good beari ng properties. The worm is normally the driver, and the action of the worm g ear is quite similar similar to the action of of a screw on a nut. Due to the wedge-like action of the worm thread on the gear tooth, it is relatively easy to obtain quiet operation with thi s type of of ge ari ng ; i t also provides a very wide ran ge of of speed speed reductions. Hypoid Gear and Pinion
This gear is used used for t ransmitt ing power power between between shafts a t right angles to each other but on different planes. The teeth have hyperbolic contours. In contrast to the conventional spiral bevel gear, where motion is largely of a rolling nature, the hypoid develops a longitudinal sliding motion motion betwee between n t he teeth of the pinion pinion and the rin g gear. This gr ea te r sliding action action between between the teeth f a se t of of hypoi
All these types have one thing in common; th contacting teeth have pure rolling action a t the pitch line but in a ny othe r position they slide on one another. This is most important since the amount and natu re of this sliding has a gr ea t effect on the gear's lubrication requirements. For example, it is well-known that the amount of sliding wit h hypoid gea rs is considerably grea ter than with spiral bevel gears and th at t he lubrication requirements fo r hypoid gear8 ar e therefor e more severe th an those of spir al beve gears. Sliding motion occurs most actively when th teet h first come int o contact. As they become disengaged, the points of the respective elements develop a certain amount of sc rapin g action on the sides of t he adja cent teeth. Both a wiping action and squeezing will be apt to occur at these times. As the teeth become more and more engaged, however, rolling contact becomes more pronounced. Wiping or sc rap ing o f of the lubr icant is less a pt to occur under these condition but the squeezing-out action still is possible, especially since maximum contact pre ssur es a re encountered dur ing the time the teeth ar e so engaged. Wear will occur more rapidly at the points and roots of t he teeth due to the sliding friction involved; whereas, the intermediate tooth surfaces adjacent to the pitch line, being subject to rolling action, will resist wear more effectively.
a. Residual (Straight Mineral)
The firs t of t he petroleum g ea r oils con sisted of heavy, stic ky residual products. These str aig ht mineral oils represented the residue left in stills after distillation of lighter fractions from certain types of crudes. They a re still used widely on spu r gear s on comparative ly slow-speed machine s in steel, cement, rubber and other mills where speeds are under 100 R P M . These products vary in viscosity from 200 up to 10,000 seconds (Saybolt Universal) a t 2 1 0 °F . The heavier varieties have to be heated to be applied (usually by pad dle ).
hey
are very sticky and represent the most adhesive of all the ge ar lubrica nts. This type product gives a thick film on gea teeth. The film separates tooth contact are as completely and the oil support s the load entirely by hydraulic action. b. Residual (Compounded)
The straight mineral type is often blended with fatty or other polar material to provide improved film str eng th and to provide adequate lubrication under bad wa ter conditions. c.
TYPES OF LUBRICANTS AND THEIR APPLICATION Due to th e complexity of modern ind ustr ial operations, scores f l ubric ants ar e required to give proper lubrication a nd protection. I n recent years, there has been a tre nd t owar ds consolida tion of the se produc ts and eliminati on of many of the unnecessary specialty products, Most lubricant manufa cturers are giving wholehearted co operation in this consolidation prog ram.
Types of Gear Lubricants Due to the va riati ons in oper ating conditions, several varieties of ge ar oils ar e required to provide adequate lubrication. The following types ar e generally use 1.
He av y Adhesive Residual Types
Residual (Cutback with Solvent)
The above types are sometimes cut back wit h a solv ent to provide ease of application. A fte r t he solvent evaporates, the heavy material remains. e c u t -b a c k l u b r i c a n t s
s h o ul d b e u s e d o n l y w h e r e t h e r e ample ventilation. chlorinated solvents are used, they may hav t o x i c e f f e c t o n p e r s on n e l petroleum-type solvents are used, t h e y w i l l p r e s en t flamm ability or explosive haxa?,d.
d. Residual (Extreme Pressure)
In recent years heavy, adhesive residual products with EP addi tive s have been developed for steelmill and other very-heavy-duty gear s where extreme pressure qualities are desired. The products can be sprayed on gears and also on bearings where severe
tions. These materials are high molecular weight org anic compounds, contain ing carbon, hydrogen and oxygen, as compared to lubricating oils which contain only carbon and hydrogen. The fatty molecule which ha s the prop ert y of t hin film oiliness, differs from the lubricating oil molecule in one other important respect, namely, that one end is highly reactive and has the property of formi ng a powerful bond with th e metal surface. It is called a "polar" molecule, and it is attracted to a metal surface much the same as iron filings are at tracted to a magnet: It is "adsorbed" to the su rfaces so powerfully that the last traces in some cases can be removed by nothing short of machining. These polar molecules, when they are attached to a surface, can be described as long molecules sticking out like the flexible bristles of a brush. Physical measure ments have shown tha t polar mole cules act in this way and the length of the molecule has been measured. Recent research work has shown that under o peratin g conditions the polar materials react w ith contacting metals, formi ng a small amo unt of metallic soap. This adds to the good lubricating qualities of the polar materials. In cases where heavy loads, low speeds or intermittent operation prevent formation f a thick film, an oiliness or pol ar-type lubric ant i s very desirable. Animal and vege table oils and fatty acids possess great oiliness. These oils are suitable for bronze-on-steel worm g ears and fo r all types of steel-onsteel gears (except hypoid) where thin film lubricating conditions exist.
2. Greases (For Open and Enclosed Gears)
Adhesive g reases 1 or 2 consistNLGI ency are sometimes used on open gears where high tem perature conditions prevail r where leakage of a thinn er lubricant might contaminate materials being processed. EP or non-EP greases can be used and application i s made by brush, paddle or pressure gun. Greases softer tha n NLGI No. 0 consistency ar e being used in enclosed gea r sets , partic ularly in coal mining machinery, where high operating temperature and leakage ar e factors. Application is usually made by pressu re gun 3. Intermediate Viscosity Oils (For Enclosed Gears) a. Straight Mineral Oil
Lower viscosity mineral oils of turbine or cylinder oil types are very well suited for enclosed high-speed single helical and herringbone reduction gea r se ts where pinio speeds may run up to several thousand R P M . These oils should be very re sis tant to deterioration in th e presence of heat, which often develops dur ing operation. Viscosities of these oils may r an ge fr om 300 seconds (SU ) t 100° F. to 250 seconds ( S U ) t 210°F These lubricants are suitable for general lubrication of all type gears (except hypoid) operati ng under comparatively lo loads and high speeds. b. Mineral Oil with Oiliness or Polar Additives
Str ai ght minera l oil of interme diate viscosity is often blended w ith a small amoun t o fa tty o r other polar material to provide improved lubrication to gears ope rating under partial boundary conditions where an E product is not required. Theory of Polar Lubrication
Part ial boundary lubrication exists where operating conditions are severe and the mineral oil film is too thin to s eparate teeth or b earing surface s completely It has long been known th at cer tain materi als, such as fatty acids or other oiliness agents are effective in reducing friction
c.
e ressure Oil (Mild Type)
Und er conditions of very heavy loads where bouddary lubrication exists and where st ra igh t mineral and the polar type oils are not effective, Extrem e Pressure-type lubrican ts ar e recommended These oils are usually available in a series of several grades which may range in viscosity fr om 300 seconds t 1 00° F. to 100 seconds a t 21 F. P additives in these oils usually contai lead compounds in the milder forms and
pounds, sometimes in combination with lead compounds in the more active types. d. Extreme Pressure Oil (Active Type)
Active-type P oils ar e used prima rily f or automotive fact ory fill on hypoid ge ar s only. In automotive gears a mild E P oil is often used for make-up. Active E P oils usually contain, lead soap and active-type sulfur. They are corrosive to copper while the milder E P oils are no corrosive. Active-type P oils ar e designed only for hypoid break-in and should not be used on other types of ind ustria l gears
T h e o r y of EP
Lubrication
When steel-on-steel bearing surfaces rub against each other, such as in g ears or antifriction bea rings, th e local high spots develop a very high temper ature due to friction. The purpose o an E P additive is to prevent welding of th e high spots. The theory is t hat at these high temperatures, there is a chemical reaction between the additives and iron. Compounds such as iron sulfide, iron chlaride, or an iron phosphorus alloy are formed . When a combination of sulfu r- and leadtype additives is used, the re is believed t o be a side reaction between the lead and s ulf ur com pounds to form lead sulfide, which adheres to the metal surfaces. These compounds are softer than iron, and they provide lubrication. This prevents welding and further tearing, and the gears can operat without accelerated failure rate. P additives a re especially effective where steel-on-steel bearing surfaces are involved and where spot temperatures get high enough for the chemical reaction to take place. It is believed, however, tha t P a gents ar not particularly effective with steel in contact with softer metals such as brass, bronze, Babbitt, cadmium o r aluminum. Unde r heavy load, these metals deform slightly and temperatures do not get high enough for th reaction to
When an Extre me Pressure lubricant is used under light-duty conditions, the Extre me Pressure additive will not be depleted, but it is available for use if heavy pressure or shock load are encountered. For this reason many operators use E P lubricants a s insurance against sudden adverse conditions. Under heavy-duty loads, the P additive wil be depleted gradually and replenishment is desired. Usually the normal make-up of fresh oil will provide sufficient additional additive to give suitable operation. In many instances E gear lubricants have been used for many years without appreciable change in E P characteristics. After long-time service, especially if operating temperatures ar e higher than normal, there will be gradual increase in viscosity due to oxidation. In such a case a lower viscosity E lubricant c an be used as make-up t o bring th viscosity down to the desired level. Lead naphthenate-sulfur type mild E P lubrican ts ar e almost universally used in steel mills fo r several reasons a. Lead naphthenate contributes to E P activity by combining with sulfur, forming lead sulfide film on metal. b. Lead naph thena te is easily soluble in min eral oils and does not separate under normal storage or operating conditions. c. It is also polar in nature and provides lubrication under boundary conditions. lubricant, providing cushioning effect and minimizing noise of gear operation, particularly in heavy-duty steel mill service. Other types of Mild E P Ge ar Oils (some containing sulfur or sulfur-chlorine or sulfurchlorine-lead combinations), are used for aircr af t gear s and fo r some automotive transmissions, differentials, steering gears, universal joints and hypoid gears. If pressures or shock loads are extremely
job, the, use of P lu bric ant s will merely postp o ne t h e e v il d a y w h e n f a i l u r e w i l l t a k e p la ce . They cannot influence the effect of metal fatigue.
t y p e s of a d d i t i v e s t h a t a r e o f t e n u s ed i n g e a r oils 1.
q u o te f r o m a n a r t i c l e in t h e m a g a z i n e L U B R I C A T I O N E N G I N E E R , D e c em b e r, 1 9 5 7, b y M r . . Cichelli of B ethlehem Steel, titled "A L u b r i c a t i o n E n g i n e e r S u r v e y s S te e l M il l G e a r ing," stresses the major importance of meta)lurgy in gear performance.
o improve th e viscosity-temperature relationship o t h e l u b r i c a n t a n d t o m i n i m i z e t h e v i s co s it y spread over the operating temperature range. V i s c o s i ty I n d e x i m p r o v e r s
"Lubrication of steel mill gea rs is only one formance-in ma ny cases t is minor. It has been demonstrated that even the best lubricants are inadequate when gear m e t a l lu r g y a n d g e o m e t r y a r e b e lo w s t a n d a r d f o r t h e j ob . W e k n ow f n o l u b r i c a n t that can substitute for toughness and hardness when these two factors are demanded." T h e f o ll o w i n g s u m m a r i z e s b r i e f l y t h e d i sc u s s io n o n E P g e a r l u b r i c a n ts . 1.
2.
3.
4.
P l u b r i ca n t s a r e n o t n e c e s s a ry o n a n y t y p e s of g e a r s w h e r e t h i c k f il m l u b r i c a t i n g conditions ex ist o w e v e r, s o m e o p e r a t o r s w a n t t o u se E P l u b r ic a n t s a s i n s u ra n c e against possible adverse conditions. P l u b r ic a n t s a r e d e fi ni te ly a d v a n t ag e o u s o n g e a r s w h e r e s p e e d a n d l o ad c o n d i t i o n s are very adverse. P l u b r i c a n t s s h o ul d n o t b e u se d i n d i s criminately, but should be wisely placed only in equipment where needed. P l u b r i c a n t s a r e n o t a c u r e - a ll f o r a l l i ll s faulty mechanical or metallurgical conditions indefinitely.
Gear Lubricant Additives
I n a d d it io n t o t h e f a t t y o r p ol ar c o m p o u n d s w h i c h a r e a d d ed t o r e du c e f r i c t i o n a n d t h e additives containing chlorine, phosphorus, sul-
o reduce the pour p o i n t o r c h a n n e l p o i n t of t h e l u b r i c a n t s o that it will flow freely at low temperatures.
Pour Depressants
3.
o prevent foam formation or to accelerate foam collapse a n d t h u s m i n i m i z e l os s of l u b r i c a n t d u e t o foaming in service. Foam Depressants
o prevent undue thickening due to oxidation and to give longer life to the lubricant. Oxidation Inhibitors
o minimize att a c k o f w a t e r a n d o t h e r c o r r o s iv e m a t e r i a l on metal surfaces. Corrosion Inhibitors
Laboratory EP Tests
S e v e r a l t y p e s o f E P t e s t s h a v e b e en d ev el o pe d f o r e v a l u at i n g E P g e a r s o i . T h e m o r e prominent are listed below The Almen Test F al ex
P Test
T h e 4 - Ba ll
P Test
The SAE E P Tes The Timken Test Som e of these tes ts wer e originally developed f o r a u t om o t i ve l u b r i c a n t s a n d o t h e r s f o r i n d us trial lubricants. Unfortunately there is no correlation between the results of the various m e t h od s . 0 n e . t e s t m a y g i v e a s u l f u r - b e a r i n g o i l a h i g h r a t i n g a n d a n o t h e r w i ll r a t e a c h lo r in e bearing oil higher than the others. n s o m e of t h e s e t e s t s t h e r e p r o d u ci b i li t y i s n o t g o od a n d t h e y d o n o t r a t e a s e r i e s of o i ls i n t h e s a m e c o m p a r a t iv e o r d e r o f P v a lu e s. T w o
signed to differentiate only between E an d non-EP oils. Most of the m achines and procedures are not accurate enough to m e a s u r e t h e v a r i o u s le ve ls of P c h a r a c teristics. 2.
T h e r e a r e m a n y v a r ia b l es , s uc h a s t h e f o l lowing, which, if not c arefu lly controlled, w il l g i v e e r r a t i c E P r e s u l t s : Kin ds f me tal used n e t S u r f a c e f in is h
Te
per atu re f oil peed
Ambient tev pe ratu re
Metal hard ness Method f applying load A n y s i n g le E P t e s t m a y d u p li c at e o n e o r t w o service conditions, and ma y be used as a screening test bu t should not be used to replace a fullscale or simulated service test for rating the
lub rica nt fo r specific application. C orrelation of P t e s t s w i t h s e rv i ce p e r fo r m a n c e i n a g iv e n piece of equipment is difficult and predicting p e r f o r m a n c e o n t h e b a s is of P t e s t s a lo n e i s not possible. M a n y E P l u b r ic a n ts , in a d d i ti o n t o E P o r "anti-weld" ma terials, also contain polar agents, sometimes referred to as oiliness additives. The latter additives are desirable and u s e fu l s u p p l e m e n t s t o P a d d it iv e s s in c e t h e y provide protection to metal surfaces during b o u n d a r y c o n d it io n s e x i s t i n g p r i o r t o a b n o r m a l c o n d it io n s w h i ch w i ll b r i n g t h e P a d d i t iv e s into action. Thc following table shows the approximate rang e of values fo r stra igh t mineral, mild E a n d h i g h E P l u b r i c a n t s w h e n t e s te d o n v a ri o u s machines
Load Almen Test
in Pounds
Straight Mineral Oil P L u br ic an t
to 16 to
35
Reproducibility
Not sufficiently precise or reproducible to dist i n g u i sh b e t w e en l e v e l s o f E P c h a r a c t e r i st i c s . Suitable for screening straight mineral oils from P oi
Pop-Up Falex
Test
Str aig ht Mine ral Oil P L u b ri ca n t
in Pounds
Reproducibility
B e lo w
N o t p r e c i s e o r r e p r o d u c i b l e e n o u g h to d i s t i n g u i s h b e tw e e n l e v e l s f P within a given grade. Suitable fo r screening straight mineral o il s f r o m E P o i ls .
75
4500
Typical Mean Hertz Load Ranges 4-Ball EP Test
KG
V a l u e s u s u a l l y c h e c k w i t h i n * l o % . Precision is b e t t e r t h a n w i t h m o s t o t h e r m e t h o d s .
Straight Mineral Oil M il d E P L u b r i c a n t H i g h E P L u b r ic a n t
Reproducibility
to
Suitable for screening straight mineral oils from P o i ls a n d f o r i n d ic a t in g l e ve ls of values.
Typical SAE Tests Test
Straight Mineral Oil P L u br ic an t
in Pounds
Below 12 25 to
Reproducibility
Values usutilly check within & 1 6 % . S u i t a b l e f o r s c r e e n in g s t r a i g h t m i n e r a l o il s f r o m oils. Not suitable for distinguishing levels of P v al ue .
Typical Timken Ti mke n
P Test
Stra ight Mineral Oi Mi d E P Lubricant
P Tests n Pounds
to 20 20 to
Rep rod uci bili ty
Approximate reproducibility for the types of oils are 2 1 0 , 2 1 5 pounds, respect i ve l y . S u i t a b l e f o r d i f f e r e n t i a t i n g b e t w e e n straig ht mineral and P o i ls b u t q u e st io n ab l e
Conclusions
E
The following conclusions can be drawn on he basis of t he above evalu a t'ions 1. None of these a re entirely sati sf act ory be cause of many variables which cannot be controlled. T h e s e E P t e s ts a r e u s e fu l i n d e t e r m i n i n g w h e t h e r o r n o t a l u br i c a n t h a s E P p r o p e r ties, but with th e exception of M ean He rtz Load, should not be used to distinguishi b e t m e n e ve ls of P v al ue . 3. In normal operations the occasional addi-" tion of fre sh lubrican t is sufficient to keep t h e E P c h a r a c t e ri s ti c s h i g h e n o u g h t o g i v e suitable protection. P t e s t s a l o ne c a n n o t b e u se d t o p r e d i c t 4. field performance reliably. Examination of Used
Gea r Oils
The followin g tests are often used to d etermine the suitabi lity of used E P ge ar oil fo r con tinued use. Viscosity
If the viscosity has increased to that of the next higher gra de some oxidation ha s probably taken place, or t he re ma y have been co ntamination with a higher viscosity oil. Addition of a lower viscosity grade will bring the viscosity down to the desired level. If the viscosity ha s decreased, i t is probabl due to contamination with a lighter p roduct. If excessive. highe r viscosity gr ad e can be adde as make- up to ra ise the viscosity to the desired level. Sediment by Centrifuge at
160°F.
This will determine th e total amo unt of dirt, oxidation sludge, bearin g we ar o r wa ter which may be present a s contaminants. If this is excessive, the oil should be cleaned up by centrifuging, filtering or settling. This test is run on a repr esentati ve sample o the used oil without using any diluent such as precipitation naphtha. The latter solven t will usually~cause rroneo us results Lead, Sulfur or Other E
Addit ive
Tes ts will determ ine the am oun t of available
Tes
Tests such as Timken or Mean Hertz Load will indicate whethe r depletion of P characteris tics is excessive and if correction is neces sary. Methods of Application t o Gears
Due to the numerous varieties, sizes, and locations of gear assemblies in a steel mill, several methods are emplo yed for application of lubr icant to the gears, inclu ding the following zj Paddle eavy residual oils ar e often applied to open gea rs by paddle. Too much is usually applied a nd th e excess is thrown off into the surr ounding area. This, of course, is very waste ful, and pre s e n t s a p oo r a p p e a r a n c e i n t h e s u r r o u n d ing area. esidual-type lubricants are 2. By Hand sometimes formed into a ball by hand and dropped i nto the gear m esh. This method has been improv ed , and the lubricant is now often m arkete d in sm all plastic bags. T h e s e a r e d r op p e d t h r o u g h t h e l u b r ic a n t opening, and the bags are eventually c h ew e d t o b i t s b y t h e g e a r s . T h i s i s m u c h cleaner operation and is preferred by operators. Drip- I n s o m e g e a r s e t s , t h e m o r e 3. fluid types f lubrican t, including th e cutback variety ar e dripped slowly onto the g e a r s , a s s h o w n i n F i g u r e 3.
n many cases, as illustrated in Figure 4, fluid-type lubricants are applied by an ordina ry pai nt brush.
By Brzish
By Pouring
n some cases the lubricant
onto the gears. The heavier varieties of residual oil must be heated before they will pour easily. he fluid-type lubricants are often placed in a sump or bath in the bottom of t he enclosed ge ar s et. One f t he gears dips into it and lubricant is transferr ed to th e contacting gears. The excess is thrown against the housing and is guided by means of tr ough s int o th e bearings or back to the sump. (See Figu re
By Bath
4-A.)
In many instances on slow-moving gear assemblies, an idler gear dips into a sump and transfers its lubricant to the other contacting gears.
By Idler Gear-
By Circzhlating System
FIGURE
rush Application
gears, lubricant is pumped from underground tank s to the gear sets and then returns to the tanks. Lubricants used in these systems are occasionally contaminated with water and mill scale and have to be reclaimed by settling, filtering and centrifuging. uring t he las t decade automatic sp ray applicatio open gears has gained considerable prominence. controlled amount of lubricant can be sprayed over the gear surface at desired .intervals, and the cycles can be controlled automatically or manually, as illustrated in Figures an 8. Size and shape of spr ay patt erns can be controlled by use of va rious typ es of noz zles, distance from nozzle to target, pressure and temperature of lubricant. The spray is usually applied on the pressure side of the ge ars prior t o meshing. I has been found that application directly t the point of mesh is often faulty, du to a ir turbulence a t t hat location Heavy lubricant s a re usually applied manually on open gearing, but experience has shown that in addition to other methods, some of t hem c an also be applied by s pr ay without difficulty. The limiting factor is the pumpability of the lubricant a t th temperature of application. The use of By Spray
(Couriesy
of
L ~ i f k i nF o u n d r y
and Xfachinc
Co.)
FIGURE 4A-Gearbox showing Bath Lubrication System ear reducer housing orged alloy steel shaft -Precisioncut herringbone gears ronzoid crank-
n systems such
LUBRlCAl PPLY LINE!
PRAY ALVE,
ZA ZZLE
FROMAIR SUPPLY
--
(Courtes~
FIGURE
c h e m a t i c s k e t c h of s p r a y l u b r i c a t i o n s y s t e m
application, especially fo r sprayin g. Sp ra y application places lubricant t the point where i t is needed an d effects great sav ing in amount used over the old handpacking or paddle applications. These savings will often pay for the spra y installation in a comparatively sho rt time.
th
Faroal Corporation)
Th e following types f dispen sing equipment ar e available fo r spr ay application: A.
Completely Portable Equipment
his reone- or
sembles a paint sp ray gun wit two-quart capacity. (See Figu re 5.) It actuated by ai r supplied through a hose
FIGURE
and Spray Application
about 35 PSI. This equipment is the least expensive and is suited especially well for application to isolated applications on open gears on track wheels of overhead cranes, presses, shear s, steam derricks, an d shovels. I t i s a ls o p r a ct i c al f o r o p e n m i t r e g e a r s o n coilveyor tables and for coating wire rope on hoist drums. Senzi Portable Equipment his equipment consists of conventional air-hperated, barrel-type grease gun installed on a 35- or 100-pound lubricant container mounted on a two-wheeled dolly. C ompressed a ir i s supplied through a hose and a lubrican line to a s pra y gun. T his type of application is practica l wh ere t he floor is in good condi tion and not obstructed. Stationary Equipment tationary or per manent units are often used when a large number of open gears operate in a limited area. These units usually employ a barreltype gre ase pump installed in a 100- or 400pound drum. Lubricant from the grease gun is piped to all the units through standard 1/3" air line parallels the lubricant pipe. line and supplies compressed air at pressures of 40 PSI or higher for atomizing lubricant through nozzles. Various types of hand- o r motor-operated spray ecluipment are depicted in Figures 6, 7, 9. Measured ua nti ty Centralized Sys tem These systems ar e used when i is desirable to spray a measured quantity (which may var y for each set of ge ars ) t definite intervals. They consist f a hand-operated r tim clock-operated lubricant pump which dispenses lubricant through lines to any required num ber of m etering sp ra y nozzles o various capacities. T h e y r e q ~ r i r e om p r e ss e d a i r f o r a t o m i z at io n f the lubricant and th e lubricant acts a s a hydraulic medium for the operation of the mea suring valve. These systems are quite new and usually more expensive than other types of spray
(Coi,rlcry
FIGURE
ball
mill
ir
A l l i s - C h rr l r ~ l c r a \ l n n r ~ f n c lt r r i r lg C o . )
anual lubricating system
the following advantages
(Cou rtesy of Alem ite Div ision f Stew artWarne r Corporatldn)
a. Minimizes waste and co ntamination. b. S aves ma n-hou rs in application. c. Eliminates accident hazards, particularly on open gears. d. Provides smooth, even coating. e. Minimizes spoilage due to d rippage on material being processed. f. Provides ease of application to difficult locations.
10 A i ~ b o r n e ork wit h oil mist o r fog lubrication of ge ars and be arings ha s been going on for a nu m ber of ye ars in many plants. A t first only the light-duty machines were lubricated in t h i s w a y b u t l a t e r i t w a s f o u n d t h a t m a n y p ie ce s of heavy-duty equipm ent could also be successfully lubricated in th is mann er. The mist lubricati on system a s illustrated Figures 10 and employs an oil reservoir w ith capacity up to thr ee gallons. T he oil is atomized to a mist or fog b y the use of compressed air. After passing a baffle, only the microscopic particles are blo wn into the delivery tubes which carry the mist to gears, bearings or other moving parts. The theory of t his type of lubrication is tha the mist will f ow through s tra igh t pipes an around bends without any appreciable condensation, but oil droplets will condense on fastm o v in g p a r t s t l o c at io n s w h e r e t h e l u b r ic a n t is needed. The low-pressure flow of ai r (usually below PSI) on the bearings also provides some cooling effect. The mist can be appl ied to gears, bearings and other parts through fitt ings which will deliver it in th e form f mist, fine o l sp ray or oil droplets. T h e c h ie f a d v a n t a g e s a r e f o r a p p li c at io n where dripp ag e from conventional l ubricants would co ntaminate the ma terial being processe and fo r lubrication in hard-to-get-at r dangerous locations unsuitable for other means of applicatiol;. St rai gh t iner al oils wit h viscosities up to
principle of oil atomization (Cocrrlesy
f C
A.
Norgren Companr~)
below the 100 0 second (S ) viscosity rang e ar often used wh er e heavy-duty lubri can t is required. The choice of viscosity and type of oil will depend on the severity of service and the viscosity required f or pro per lubrication of the par ts. B y use of he ated a ir, oils of con siderably higher viscosity may be used. Gear Lubrication in Heavy industrial Equipment
All industrial operations involve the use of gears of one type or another. Some perform comp aratively light service but in m ost of the heavy industrial operations the gears as well as the lubricants mu st be very rugged so as to stand up un der all sorts of adverse o perating conditions. These may include high load, high
EARTH-HANDLING EQUIPMENT
( 4 - -
The operating parts of earth-handling equipment such as shovels, draglines, backhoes and cranes are usually exposed to cont a m i n a t i o n w i t h w a t e r a s w e ll a s a b r a s iv e d u s t a n d d i r t . V e r y a d h e si v e ty p e l u b r i c a n t are usually used on the gears and dipper sticks to provide a thick coa ting of oil which will minimize the effect of abrasive material s w el l s w a t e r w a s h i n g a n d r u s t in g . T h i s type of lubricant also assures efficient lubrication for a long period of time and, due to its thick, clinging film, provides quiet operation. It also gives good lubrication to equip-
(Courte sy of Bucyrus-Erie Camp ang)
FIGURE
650-B stri pp ing shove
(Courtesy
FIGURE
f Koehring C omp any
05 excavator
FIGURE airmount jaw crusher such
(Courtesy of Pioneer Engineerircp D i u i s i o r ~of Poor and C o . , Inc.)
(Courtesy of Allis-Chalrncrs Alnnufncttrrir~gC o . )
m e n t o p e r a t i n g o n u n e v en t e r r a i n w h e r e c o n siderable shock loading exists. Figures 12, d e p i c t t h e h e a v y - d u ty s e r v ic e a n d 13 the contaminating influences under which gears in earth-handling equipment must operate. CEMENT M I L L S Crushers
T h r e e t y p e s of c r u s h e r s oll, jaw or gyratory are used for crushing rock in c em e n t m a k i n g o r f o r o t h e r p u r po s e s Rock is received in varying sizes up to 3 f e e t i n l e n g t h a n d- p r i m a r y c r u s h i n reduces the size to 4 inches or less. Press u r e s i n t h e s e m e c h a n i sm s a r e t r e m e n d o u s and a great deal of heat is developed. The ge ars a s w 1 as bearings ar e subjected to very heavy shock loads, extreme temperature and considerable dust and grit. In many of the crushers lubrication of
FIGURE 16 utaway of pioneer 54 24 triple roll crusher FIGURE 17 allpeb grinding mill used for secondary grinding to produce finished cement
consisting of a pum p, sum p tank , a filter t o r em o v e g r i t a n d cooler to keep t he oi t e m p e r a t u r e b el ow 1 3 0 ° F . A m i l EP g e a r oil in the viscosity range of 300-500 seco n d s a t 1 0 0 ° F . i s u s u a ll y u s ed . Figures 15 and 16 illustrate the jawand roll-type crushers. Grinders
Cement and o ther similar indus tries emp lo y b a ll , p eb b l e a n d r o d m i l l s f o r g r i n d i n g rock to very fine sizes. The mill usually contain s 43 to 45% by volume of steel balls or rods and the cylinder revolves horizontally on its axis. Th e mill is revolved by m eans of a r in g e a r a r o u n d t h e c i rc u m f er e nc e at o n e e n d . t i s u su a ll y p r o t e c te d b y a g u a r d t o s a f e guard personnel and to keep out extraneo u s m a t e r i a l s m u c h a s p os si bl e. A n a d h e chars i v e r e si d u a l g e a r o il w i t h m i l d acteristics is usually used a s a lubr icant. F i g u r e 1 7 i l l u s t r a te s o ne t y p e of g r i n d i n g
Kilns and Dryers
Many industries, including cement, util iz e c y l in d r i c a l k i l n s a n d d r y e r s f o r c a lc i n i n g o r d e h y d r a t i n g v a r i o u s m a t e ri a l s S o m e of t h e s e a r e 1 0 f e e t o r m o r e i n d i a m eter and 200 to 400 feet in length. They re installed in a horizontal position, usually with slight slope, to allow the cont e n t s t o m o ve s l o w ly t o w a r d s t h e e x i t e n d . T h e y r o t a t e a b o u t R P M a n d t b e m o t io n is actuated by a motor opera ting throu gh a speed reducer and pinion gear which turns the large girth gear. Theplatter is lubricated by dipping into a reservoir or by means of a n idler gear. Heavy cylinder o il o r m il d E P t y p e l u b r i c a n t s a r e s a t is factory. The lubricant must operate under high heat conditions. Cement kilns have an internal tempera t u r e of a p p r o x i m a t e l y 2 7 0 0 ° F . s o t h lubricant must be resistant to oxidation. O t h e r a d v e r s e c o n d i ti o n s i n c l u d e c o n t a m i n a ti o n w i th d u s t , a n d a t i m e s w a t e r w a sh ing, since many of the girth gears are e x p o se d t o o u t s i d e a t m o s p h e r i c c o n d i t i o n s F i g u r e s 18 s h ow g i r t h g e a r s o n several kilns and dryers.
(Courtesy of A llis -Ch alm er~ Manufacturing Co.
F I G U R E 18 processing
otary kilns for pyrochemical
(Courtr ry of Allis-Chnlmers hlunufacrrrrlng Co.
FIGURE 19-9% ft. rotary cement k i ln , s h o w i n g g i r t h g e a r d r i v e m e c h a n i s m a n d r i d i n g r i n g w i t h r o ll e r
O t h e r g e a r - o p e r a t e d n z a c h i n e r y used in c e m e n t m a n u f a c t u r e i n c lu d e c r a n e s , co n veyors, elevators, shovels, pumps, pulverizers, centrifuges, and thickeners. MINING Hoists
T h e g e a r s u se d i n o p e r a t i n g a m i n e h o i s t a r e a m o n g t h e l a r g e s t u s ed i n a m i n ing operation. If the gears are open they can bc lubricated with a residual-type oil b u t i f t h e y r e c lo se d t h e y a r e u s u a l ly l u bricated by dipping into a reservoir of mild type ge ar oil or a heavy cylinder o il . T h e s e g e a r s a r e h o u se d i building so there is no serious contamination problem. Figure 20 shows the gear arrangem ent in double drum mine hoists. Mining Machines
Modern underground mining machines
(Courlcsu of Vulc un Iror Works C o . )
FIGURE (Co~ir tcsy f Jo Alnnufacturing Capany)
20
ouble drum mine hoists
lubricated w ith s trai gh t mineral oil, cylinder oil containin g polar material or mild g e a r o i . S o m e m a c h in e m a n u f a c t u r e r s o b je c t t o t h e u s e of P o i ls i n g e a r s e t s containing fr icti on clutches because of possible slippage. Oth er manufacturers do not object. Whe re leakage is a fa ctor, special greases, softer than NLGI Grade, re being used with considerable success. High temperature and contaminationr with w ate r and !arge a mo unts of coal dust a r e o f t e n e x p e ri e n ce d i n m i n i n g m a c h i n e , lubrication. Figure 21 illustrates a modern miner an d loader used in und ergrou nd coal mines. machine?-y o p e r a t e d b y g e a r s includes load ers, shuttle cars, cutters, hoists, locomotives, crushe rs, jigs, shak ing screens and conveyors.
O t h e r mining
STEEL MILLS
Steel mill gears often operate at high speeds, und er heavy loads and sub ject to high heat radiated from hot steel being processed. In addition, the g ear lubricants i n s e r v ic e a r e a p t t o b ec om e c o n t a m i n a t e d wi th fine mill scale an d w ater. Open gears, which are normally lubricated with heav y residual lubricants, are being gradually replaced with enclosed g e a r s . T h e s e a r e l u b ri c a t e d w i t h s t r a i g h t mineral oils, compounded oil or mild EP lubricants. Figures 22, 23, 24, 25 and 25-A illustr at e a few types of steel mill gears. Th following list shows few examples of e q u i p m e n t a ct u a t e d b y g e a r s Ore Bridges Hoisting Equipm ent Gas Producers
L a d le C r a n e s Ingot Buggies O v e r he a d C r a n e s
36" ill ent ry table for 30 F I G U R E . 24 cold breakdown mill. Cover of one drive removed to show arrangem ent of spur and bevel gearing
(Cotifiesy of F o r r e l - R i r n ~ i r ~ g h u ~ornpony, Irrc.) r~
SUGAR M I L L S Grinders
Sug ar mill gea rs operating the grinders are quite heavily loaded and some initial pitting of new gears may take place but it usually subsides a fte r the gears ar e su ciently broken in. Some of t he older mills have conlpletel open gearing with no slush pans. They are lubricated with heavy residual-type lubricant applied manually. The more modern mills are equipped wit h enclosed gear cases wit h oil slush pan into which the gears dip. less viscous type of gear oil in the pans enables the gears to be self-lubricating,
Great care is taken in sugar mills or other food-processing plants to make sure that the lubricants do not contain materials that would be toxic if accidental contamina tion should take place. Figure 26 shows view of the gear train in a modern sugar mill.
O t he r t l ~ p e
s u g a r m i l l m a c h i n e s include
the following Tracto rs
Cane Carrie rs
Harvesters
Cane Crushers or
Elevators
Grinders
Conveyors
Grandators Dryers
FIGUR Herringbone ge reductilon set showin] p r a n g (:merit
sspr
lubiicalLion
FIGURE
~ n ~ d e ug m confiistin ,six three-roll .milk, each wi mill
ow
dripe. Grjtdi catacity is tons of cane dfiYi. Eqclos,ec reductf on ge: closed herr inghone
OTHER TYPES OF E Q U I P M m T
In addition to th e above types of heavy industrial equipment the following list shows other types of in dust rial machinery in which gear lubrication is very important. The choice of lubr icant f or these machin es will depend on man y facto rs such a s whether open or enclosed gears are involved, speed, temperature, pressure, and if there is contamination with dirt, abrasives or water.
Grain Elevators Gravel Handling and Washing Laundry Machinery
Washing machines, ironers, extractors Driers, starch mixers, dampeners Machine Tools Marine Machinery
Jacking engines, telemotors, windlasses Capstans, deck winches, steering en'gines Materials-Handling and Hoisting Equipment
Baking Machinery
Cranes, ore bridges, unloaders, car dumpers
Mixers, flour handling, dividers, rounders, moulders and traveling type ovens.
Metal-Forming Machinery
Boiler Plant Machinery
Paper Mills
Z::anomizers, coal- and ash-h andl ing conveyo rs. Bottling Mach inery Clay Products Industry
Skip hoists, rolls, disintegr ators, g ranu lato rs Pu g mills, augers, grin ders Brick and tile cutters and pressing machines Clay-distributing equipment Plungers, screens and ball mills Coke Ovens
Exhausters, blowers, pumps Coal- and coke-handling equipment Charging machines, door extractors Pushing machines, electric locomotives
Chemical mixers, digesters, agitators, pumps, dryers Pneumatic Machinery
Air hoists Printing and Binding Machinery
Web presses, bed presses, platen presses Paper feeders, folders and cutters Binding and composing room machinery Pumps Road-Building Mach inery
Concrete Mixers
Scarifiers, graders, surfacing and finishing machines Pavers
Distilling and Brewing Equipment
Rock Products Machines
Power-transmission equipment, bottling machines
Scarifiers, graders, ball mills, tube mills, Rotary screens
Dredges
Rubber Machinery
Elevators and Escalators
Crackers, washers, mixers, calenders
Glass Making
Textile Machinery
Polishing and grinding machines, overhead cranes
Cotton, silk and woolen mills Printing and knitting machines
teeth and to make sure there is no misalignment.
~merican ear Manufacturers Association Activities
F o r m a n y y e a r s t h e A G M A h a s r e co m m en d e stra igh t mineral gea r oils and a f ew compounded with fatty oils for various types of industrial gears. Nearly all f th e gear m anufa cturer s adhere str ictly to t he AGM A specifications A brief ext rac t f the "AGMA S tan dar d Spe cification for L ubrica tion of Ind ustr ial E nclosed Gearing" AGMA 50.02 Dec. 1955 is shown on page 30. However, in recent years t her e has! been trend in industry tow ards the use f mild E lubricants w here hea vy-duty conditions require s u ch p r o du c ts . T h e s e E P l u b r i c a n t s h a v e p e r formed well. Recently AGMA has developed a new specification which recomm ends the use f mild E type gear lubricants for certain applications. n abs tra ct of th is new specification "Tenta tive AGMA Sta ndard 252 01 Mi d P L ubricants for Industrial Enclosed Gearing" May 1959 is sllowil on page 31. The AGMA is to be complimented on their efforts over the years to standardize the types f lubricailts best suited fo r all va ri ti s gears. Gear Manufacturers Activities
S in c e t h e g e n e r a l t r e n d i n i n d u s t r y i s t o w a r d s greater loads, higher speeds and force-feed lubrication, the gear manufacturer is continually cooperating to improve gear performance. Following are some of the procedures 1.
Improved steels and heat treatments are being used. These are restricted to some extent by limitations of machinability.
2.
Accuracy of manufacture is stressed. Accurate tooth spacing is especially important with high-speed gears. Inaccuracies will result in lubricant fa ilure as well as gear tooth failure and will cause loss f power trans mit ted. Tooth sur fac e finish also is important. Rough finishes usually result in high operating temperatures,
4.
Improved guards are being provided to keep oil in the housings and to prevent contamination.
5. The use of welded steel gears to replace cast gears is being extended. This provides gear teeth with greater strength and resistance to wear and reduces the possibility of hidden defects within the gears. 6.
Manufacturers are continually modernizi n g a n d r e d e s i g n in g u n i t s a n d a t t h e s a m e time incorporating the latest methods of heat treatment and other metallurgical and manufacturing improvements. By taking advantage of newest techniques gear units can be made to closer tolerances, and this provides increased capacolder styles. ity ratings as compare Gear lubricant
Choosing
Although a great deal of research has been carried out, a form ula fo r computing the proper viscosity and type of gear lubricant has never been developed, due to the complexity of fac tors involved. Usual p ractice is to select the lubricant on the basis of previous practical field experience with g ea r operation u nder various conditions. One investiga tor' ha s presented the following formula which, it is claimed, will aid in predicting loads a t which scoring will take place, using speed of the pinion, viscosity of lubricant and bulk oil temperature values. bT) /N
where
Scorin g loa Rotational Speed of Pinion Nom inal viscosit Bulk oil temper ature a and b
C o n s t a nt s f o r t h e m a c h in e
lubricant for a specific application can usually be solved by reference to the immense body of practical experience that has been accumulated in this field, the final choice is essentially an empirical one and the theoretical justification for it is not always clear. However, the progress achieved in recent years encourages the belief t ha t a full solution of t he imp or ta nt problem of predict ing the performa nce of ge ar s o all kinds is not indefinitely remote." Other in-, vestiga torsl have shown th at th e viscosity of a gear lubricant is an important factor in the+ power-transmitting capacity of gears. They. have presented the following formula (which is an adap tat ion of Lewis' origina l equation fo predicting maximum gear tooth loads). Spby
where
2K
Tooth load
ounds
Safe static stress Circular pitch
nches
=Width of face
nches
Tooth form fac tor =Ab sol ute viscosity in Ib/min. ft Constant assumed by manufactur er Pitch line velocity Based on th is modified Lewis for mula, F ig ure 27 shows the effect f viscosity on transm itt ed power for gears on a test apparatus at one speed 000 RPM. Since it i s difficult t o predict types of lubricants required fo r various types of gears i t is usually necessary to actually run laboratory tests using the specific gears involved. The following types are being used in a large petroleum laboratory testing program. Traction Motor Gears Open Gears Borsoff, Accinelli and Cattaneo, "ASME Transactions, 1951."
FIGU""
""
High-speed Aircraft Gears
B.
Hypoid Gears
This condition can develop because of improper design, faulty installation, fau lty operation, development of misalignment or worn-out gears. Excessive noise shourd be investigated promptly.
Since at the present tim e the re is no suitable f o rm u l a f o r a r r i v i n g a t t h e p r o p e r l u b r ic a n t t o use on specific ge ars , the choice is usually ma de after consultation with various groups interested in the lubrication problem. 1.
The g ear m anu factu rer usually) depends of lubricants; he prefers those yhich he knows have performed well in similar service in the past.
2. Th e ma nufa cturer f equipment in which th e gea rs a re used also is usually consulted. 3.
4.
Th e user of the g ears, of course, can apply whatever lubricant he wishes, (after the g u a r a n t e e p e r i o d ) , b u t i t i s of u t m o s t i m p o r t a n c e t o h a v e t h e r i g h t l u b r i ca n t i n his equipment. The lubricant supplier likewise, on basis of field experience has definite ideas as to the best lubricant to use; however, his recommendation should be tempered by the desires of the other people involved.
TROUBLE-SHOOTING SECTION Removal of Water and M il l Sca
Gear lubricant circulating systems often are contaminated with water, mill scale, dirt and fine metallic particles representing wear. This may result in an emulsion. Experience has shown that the lubricant can be cleaned up by one or more of the following procedures.
C.
Noisy Operation
Foaming
Foa min g in a ge ar box may occur fo r one the following reasons 1.
Oil level too high, resulting in excessive churning.
2. Ce rtain ty pes of ad ditives may cause foaming. 3,
Water in the oil may cause foam, especially if operating temperature is high.
Foam ing is objectionable since it may caus oil starv ation on th e g ear teeth as well as leakage from the box. D. Lubricant Thickening
This can be caused by (1 contamination with a heavier oil, (2) contamination with ext r a n e o u s m a t e r i a l s u c h a s w a t e r , d i r t , s c al e o r metallic we ar p articles, or by oxidation due to long service or excessively high operating temperatures. Fine metal particles, especially c o p p e r o r b r a s s , a n d w a t e r w i l l a c t a s c a t a l y st s fo r promotion of oxidation. The final result may be form ation f petroleum acids, varnishes, lacquers or coke-like deposits if conditions are severe enough. The continued use of a badly thickened lubricant can result in eventual gear failure.
1. H e a t l u b r i c a n t u p t o 1 6 0 ° F . o r h i g h e r i f
necessary, allowing water and solids to Centrifuge at 160°F. or higher to break the emulsion.
3.
If th e emulsion is extremely tight, a smal am oun t (u sually 0.10% or less) of emulsion breaker can be used to sep ara te the contaminants from the oil
Lack of Adhesiveness of Residual Type Lubricants
Occasionally heavy residual type lubricants f a i l t o a d h e r e t o g e a r s a s t h e y s h o u ld . T h i s i s probably due to failure to clean gears sufficiently to remove previously used gear oils.
to occur. These can be charg ed chiefly to fault operating or m echanical conditions. The lubri cant is very seldom a t fault if the prop er type and amount is applied and if there is no excessive contamination. Brief descriptions of the various types of failure s ar e tabulated belo 1.
Wear
Flaking
Occurs when thin flakes of metal are removed from gea r teeth. I t can be caused by surfac e fatigue or a s a result of tensile yielding under combined rolling and sliding action. I t is usually associated with softer steels or with bronzes. Ordinarily this only occurs during the initial period f o peration and is usually not serious.
Normal Wear or Polishing
Slow loss of metal from gear surfac$ th at will not affect th e expected life f the gears. Destructive Wear
Heavy wear causing change in tooth shape, resulting in shortened life and noisy action. Abrasive Wear
I n j u r y c au s ed b y m e t a l o r o t h e r a b r a sive particles passing through the gear mesh. Scratching
Is a severe form of abrasive wea caused .b y ha rd foreign pieces passing through the gear mesh. If the cause is removed in time damage is usually light. Scoring
This repre sents rapid removal of metal by tearing due to metal-to-metal contact. It can be caused by ru pt ur e of oil film due to excessive coilcentration of the load in certain areas or an unsuitable lubricant. Interference Wear
Is caused by impro per concentration load a t the point of enga gem ent of th driving flank with the mating tip or at disengagement of the driven flank and m a t i n g t i p . I t m a y r e s u lt i n s e v e r e d a m age and eventual failure.
Burning
This is the result of excessive tempera t u r e e i t h e r f r o m e x t e r n a l s o u r c es o r a s a result of friction due to high loads or speed o r inadequa te lubrication. It i s characterized by tem per atu re discoloration of the contacting or adjacent surfaces. 2. Surface Fatigue Initial Pitting
Involves light pitting, usually occu rring t the beginning of operation and diminishing when high spots are worn down. It usually occurs in a narrow band near th e pitchline. t is not serious an d usuall corrects itself Destructive Pitting
This usually st ar ts below the pitchline and the pits increase in size and number. Eventually the tooth shape may be destroyed a nd ma y lead to failure by fatigue breakage. Spalling
Often occurs in hardened steel and originates from a surface defect or internal st ress following heat treatmen t. It is characterize d by larg e particles flaking out of tooth su rfaces, usually on top edges or ends.
3. Plastic Flow Rolling and Peening
Corrosive Wear
This represents surface deterioration which may be caused by conta min ation o
Ar e caused by sliding action under excessive loads and impact loading due to improper tooth action. They a re charac-
ridge near the pitchline of the driven gear. Tooth profiles become badly deformed before complete failure. Rippling
This is a wave-like formation on the s u r f a c e a t r i g h t a n g l e s t o t h e d i re c t io n o f s l id i n g . I t h a s fish-scale appe aran ce an occurs on case-hardened hypoiil pinions. t i s n o t s e r i o u s u n l e s s a l lo w e d t o c o n t i n u e . t can be caused by friction $ue to insufficient lubrication, heavy loads or vibration. Ridging
This occurs on tooth surface of caseh a r d e n e d h y p oi d p i n i o n s a n d b r o n z e w o r m g e a r s. I t m a y a p p e a r as d i a g o n a l r i d g e s o r a s a h e r r in g b o n e p a t t e r n o c c u r ri n g i n the d irect ion of sliding. Thi s is usually associated with excessive loads or insufficient lubrication and may result in complete failure. Breakage Fatigue Breakage
T h i s r e s u l t s f r o m b e n d i ng s t r e s s e s be y o n d t h e l i m i t of t h e m e t a l. T h e s e s t r e s s e s c a n o r i g i n a t e f r o m p o o r d e s i g n , o v e rl o a d , misalignment or surface defects. Break-
a g e u s u a ll y s t a r t s a s a c r a ck o n t h e loaded side. Breakage from Heavy Wear
S e v e r e p i tt i n g , s p a l l i n g o r a b r a s i o n c a n remove enough metal to reduce the stren gth of th e tooth to its breaking point. Overload Breakage
R e s u l t s f r o m s u d d e n s h o ck o v e rl o ad a n d d o e s n o t s h o w p r o g r e ss i o n f r o crack as in fatigue. Harder materials have a s i lk y a p p e a r a n c e a n d d u c ti l e m e t a l s h a v e a fibrous or tor n app earance. Misalignment or entrance of a large piece of fore i g n m a t t e r i n t h e m e s h m a y b e c o n tr ib u t i n g c a u s es . Quenching Cracks
These cracks originate from internal s t r e s s e s d ev e lo p e d d u r i n g h e a t t r e a t m e n t a n d a r e v is ib l as h a i r l i n e c r a c k s . T h e y often are the focal points for fatigue b r e a k a g e o r o v e rl o a d b r e a k a g e . Grinding Cracks
The se f ine sur fac e crac ks a re developed by improper grinding technique or heat t r e a t m e n t . O f te n t h e y d o n o t a p p e a r u n t i the gear has been subjected to load. C r a c k s a r e o r i g i n a ti n g p o i n ts f o r f a t i g u e b r e a k a g e o r s u r f a c e s p a l li n g .
E CLASSIFICATION VISCOSITY RANGES Motor Oil SAE Vis. No.
Viscosity Range, SUS, (Oct. 3, 1950) at 210°F.
at O°F. Minimum
Maximum
Minimum'
Maximum
4,000 W
0
Belbw 12,000
W
48,000
20
Below
30
58 70
40
Below
85
50
85 110
O°F. 210°F. is. is above A-Can waive min. vis. SUS. 0°F. 210°F. is. is above B-Can waive min. vis. SUS. *-Crankcase oils mu st have viscosity not less th an 39 S U S a t 210°F.
Gear Oil SAE Vis. No.
Viscosity Range, SUS, (Jan., 1953) at 210°F.
t O°F. Minimum
Maximum
Minimum*
Maximum
15,000 80
15,000
)
100,00
90
75
120
140
120 200
200
250
0°F. 210°F. is. is above A-Can waive min.'vis. SUS. 210°F. 0°F. is. is below 750,000 US. (Extrapolated.) B- an waive max. vis. -. and axl e lubes mu st have vis. not less tha S U S a t 210°F.
NLGl GREASE CLASSIFICATION NLGl Grade o.
00 00 0 1 2 3
ASTM Worked Pen etratio n 77OF. Min.
Max.
445 400 355 310 265 220
475 430 385 340 295 250
AGMA STANDARD SPECIFICATION FOR LUBRICATION OF INDUSTRIAL ENCLOSED GEARING A G M A 250.02 --DECEMBER
TYPE OF OIL
1955
a. Shall be high quality, well refined, petroleum oil. b. Shall be noncorrosive to gears, to ball, roller and sleeve b6arings. . SGall be neutr al in reaction, fre e fr om g ri t or abrasiveness, have good defoaming properties and good oxidation resistance. d. Shall be straight mineral oil with following exceptions: (1) Fo r worm gears, addition to 1 0% animal fa t such as acidless tallow, is desirable. (2) Special additives are permitted in applications where speeds, loads or temperatur es are abnormal.
VISCOSITY
a. Viscosity Index (Dean Davis) of 30 minimum is allowed fo r ordinary applications. Where operating temperatures var more th an 80°F., a viscosity inde x of 60 minim um is desired. Oils meeti ng AGM cornp, 8 comp and 8A comp must have a minimum viscosity index of 90. b. Viscosity must be within the ranges shown below:
AGMA Nurnher
Viscosity Range SUV Seconds 100°F.
210 F.
TENTATIVE AGMA STANDARD SPECIFICATION D EXTREME PRESSURE LUBRICANTS FO INDUSTRIAL ENCLOSED GEARING A G M A 2 5 2 . 01 - -M A Y
SCOPE
a. Applicable to following typ es of g earing Helical IEerringbone Stra ight Bevel Spiral Bevel b.
T YP E O F O I L
195
Not applicable to worm gearin g (consult
Shall be a mild E xtre
Spur
anu fac ture rs).
e Pres sur e oil with following characteristics.
a. No sep ara tion of oil and add itive. b. Hav e maxim um resistance to foam ing under normal operating mo isture conditions. c. Non-corrosive to metals encountered even in presence of moisture. d. Hav e minimum Timken E P test of OK 30 pounds load. e. Contain no dir t, abrasive or othe r deleterious materials. f. Sufficiently stable to give normal service life in AGMA standa r d g e a r s o p e r a ti n g a t t e m p e r a tu r e s u p t o 1 6 0 °F . VISCOSITY
a. Ha ve min imum Viscosity Index of 60. (D ean b. Viscosity of va rious grade s below.
Davis)
ust be within the range s shown
V I S C O SI T Y R A N G E O F A
Luhricant Numher
Sr:
A L UB R IC A NT S
Viscosity Ranges 100°F.
SUV Seconds 210°F.
VISCOSITY SYSTEM FOR INDUSTRIAL FLUID LUBRICANTS ASTM
In recent years, there has been considerable interest on the pa rt f users of industria l lubricants in a viscosity classification system which will be adaptable to electronic data procegsing machines for statistical listing. This is especially needed by companies who may purchase a varie ty of lu brica nts fr om various petro?eu suppliers, The ASTM-ASLE Viscosity System is in process of adoption by industry. Its purpose is
D-2422-651
to s tandardize and simplify visc o~i ty lassifica tion s of indu stri al lubricant s. Only 16 different viscosities are used, with a uniform viscosity tolerance 10% for all grades. All viscosities are based on a tempera ture of 100°F. This System simply groups industrial lubricants by viscosity ranges. It is similar to the SAE numbers used to designate automotive lubricant viscosities. Neither system evaluates lubricant quality.
VISCOSITY CLASSIFICATION
Viscosity Grade N u m b e r , SU 100°F.
Kinematic Equivalent cs 100°F.
TYPES I.
G E AR
L U B R I C A N T S
ea vy Adhesive Residual Type (For Open Gears) a. Residual (Stra igh t Min eral) T e x a c o C r a t e r 0 0 , 0 , 1, 2, 3, b.
Residual (Compounded) T e x a c o C r a t e r A , l,X, 2 X , 5 X , 1 0 X R e s i d ua l ( C u t b a c k w i t h S o l v e n t ) T e x ac o C r a t e r 2 X F l u i d a n d
Fluid
2. Greases (For Open a d Enclosed Gears) T e x a c o M a r f a k 0 0, 0 a n d Texaco Marfak Heavy Duty Texaco Thermatex 000 Texclad
a n d 2 ( F o r O pe n G e a r s )
3. Intermediate Viscosity Oils (For Enclosed Gears) a. S t r a i g h t M i n e r a l O i l
Texaco Thuban 80, 90, 140 and 250 Texaco Regal Oils PC-R&O, PE-R&O, F-R&O, G-R&O, H-R &O b.
Mineral Oil With Oiliness or Polar Additive Texaco Honor Cylinder Oil Texaco 650T Cy linder Oil
4. Extreme Pressure
il (Mild Type
Texaco Meropa Lubricants
1,
3,
4, 5, 6, 7 , 7 H , 8 a n d 1 0
Texaco Universal Gear Lubricants HD 80, 90 and 140
5. Extreme Pressure Oil (2 I05B Type)
TEXACO RECOMMENDATIONS FOR GENERAL INDUSTRIAL GEAR LUBRICANTS
Type of Gear
Description
Ambient Temperatures
Below 40" F. Gears enclosed, casings oil tight, bearings separately lubricated.
G e a r s e n c l o s ed , casings oil tight, g e a r l u b r ic a n t t o s e r v e b e a r in g s a well. Spur, Bev.:l Spiral Bevel, Annular or Internal
e a r s e n t ir e l exposed, han d lubricated.
Gears exposed, bath lubricated.
G e a r s e n c l o s ed , c a s i n g s oi l t i g h t , b e a r i n g s seprrr a t e l y l u b r ic a t e d ,
G e a r s e n cl os e d casings oil tight, g e a r l u b r ic a n t t o serve bearings a well. Helical or
Herringbone
G e a r s e n t ir e l exposed, hand lubricated.
G e a r s e x p o se d , bath lubricated.
Normal Operation
Heavy Duty, Where Extreme Pressure Lubrication Required
In Presence of Water or Chemicals
Thuban 80 Regal Oil PC R&O
M e r op a L u b r i c a n t - 1
Thuba n 9 Re'gal Oil G R&
Meropa Lubricant-3
A b o v e 1 0 0 " F.
Thuban 140
Meropa Lubricant-6
B e l o w 4 0" F
~egal Algol Oil
Meropa Lubricant-1
40" to 100 F.
R e g a l O i l G R& O Thuban 90
M e r op a L u b r i c a n t 2or3
A b o v e 1 0 0 " F.
Rega I Oi Thuban 90
h fe ro pa L u b r i c a n t 3
Below 40" F.
Crater or 2X Fluid Texclad
Merop a Lubricant 2or3
Crater 1X
40" to 100" F.
C r a t e r 1 , or 2X Fluid Texclad
Meropa Lubricant30r4
Crater lX , 2 or 2X Fluid
Above 100" F.
Crater Texclad
Meropa Lubricant-6
C r a t e r 2X o r 2X Fluid
Below 40" F.
Regal Oil G R&O Thuban 90
Meropa Lubricant-3
40' to 100" F.
Thuban 140 or 25 C r a t e r 0 0 O o r 2X F l u i d Higra
Meropa Lubricant6 or 8
Crater 1X
Above 100" F.
Thuban 25 C r a t e r O , 1 ,2 o r 2 X F l u i d Higra
Meropa Lubricant-8
Crater 1X or 2X Fluid
Below 40'
R e g a l il T h u b a n 90
Meropa Lubricant-3
40° to 100" F.
Rega l Oil G R&O Thube n 90 or 140
Meropa Lubricant3or6
Above 100" F.
Thaba n 14
Meropa Lubricant-6
Below 40" F.
R e g al O i l P E R & Algol
Meropa Lubricant-1
40" to 100" F.
R e g a l Oi T h u b a n 90
Meropa Lubricantlor2
A b o v e 100'
R e g a l il G R & O Thuba n 9
Meropa Lubricant-3
Below 40 F.
Crat er O,1 or 2X F luid Texclad
Meropa Lubricant-3
Crater 2X Fluid
40" to 100° F.
C r a t e r 1 , 2 o r 2X F l u i Texclad
Meropa L ubricant 6or8
Crater lX , 2 or 2X Fluid
A b o v e 1 0 0 " F.
Crater l,Z or 2X Flui Texclad
M e o pa L u b r i c a n t 8
Crater lX , 2 or 2X Fluid
Below 40" F.
R e g a l O i l R& Thuban 90
Me ropa Lubricant-
Crater lX
40" to 100" F.
Thuban 140 r 25 C r a t e r 0 0 , 0 o r 2X F l u i d Higra
Meropa Lubricant6 or 8
Above 100" F.
T h u b a n 250 Cra ter 00,0 or 2X Fluid Higra
Meropa Lubricant-8
40. to 100o
F.
R&
r 5X Fluid
TEXAC O REC OM MEN DAT IONS
Type of Gear
Description
Ambient Temperatures
Below G e a r s e n cl o se d , casings oil tight, bearings separ a t e l y l u b r i c at e d .
Gears
Won11
casings oil tight, gear lubricant to s e r v e b e ar i n g s a well.
Gears exposed, bath lubricated.
Teeth
Rack an
Pinion
e x p o s ed , h a n d I u bricated.
Teeth
Honor Cylinder Oi T h u b a n 90 Rega l Oil G R&O
M e r o p a L u b r i c a n t- 3
A b o v e 100" F.
Honor Cylinder Oi 650T C y l i n d e r O i T h u b a n 140
erop a Lubricant-
Below 40° F.
Regal Oil PC R& T h u b a n 80 90
40"
Hon or Cylinder Oi T h u b a n 90 Rega l Oil G R&O
erop a Lubricant-
A b o v e 100" F.
Honor Cylinder Oil 650T Cylind er Oil T h u b a n 140
M e r o p a L u b r i c a n t- 6
Below 40" F.
Regal Oil T h u b a n 90 Texclad
40"
100"
100" F.
100° F.
Below 40" F.
Regal Oil G R&O T h u b a n 90
40"
100' F.
T h u b a n 140 Higra
A b o v e 100" F.
T h u b a n 140 Higra
Below 40" F.
C r a t e r 00,O. 1 Texclad
100" F.
C r a t e r 1,2 Texclad
A b o v e 100" F.
Crater 3 or Texclad
' to
F.
Meropa Lubrican tlor3
T h u b a n 140 Texclad T h u b a n 140 C r a t e r 0,1 Texclad
40"
In Presence of Water or Chemicals
erop a Lubricant-
A b o v e 100" F.
A b o v e 100" F. NOTE S: The more or less and for small In case of
Heavy Duty, Where Extreme Pressure Lubrication Required
Normal Operation
erop a Lubricant-
F.
Below 40" F.
bath lubricated.
I N D U S T R I A L G E A R L UB R IC A NT S
Regal Oil C R&O T h u b a n 80
Gears
e x p o se d , h a n d l u bricated.
F O R G EN E RA L
Fluid
Meropa L ubricant-
Crater Fluid
ero pa Lubricant-6
Crater Fluid
erop a Lubricant-
250
M e o pa L u b r i c a n t 6
Crater
M e r o p a L u b r ic a n t 6o
Crater
luid Meropa Lubrican L-6 Fluid Fluid
Crater Fluid
Meropa Lubricant-
C r a t e r IX, X Fluid
Meropa Lubrican t-
C r a t e r 2X, 5X
10
Fluid
Reg al Oil G R&O T h u b a n 90 C r a t e r 00 Fluid
erop a Lubricant-
Crater
T h u b a n 140 C r a t e r 00.0
ero pa Lubricant-6
Crater
T h u b a n 140 Crater
a bo v e re co m m e n da ti on s n a t u r a l l y a r e general, based on average pressures to medium sized gears: light loads or high speeds: Use next
Fluid 250
Fluid
M e r o p a L u b r i c an t 6o
luid
Crater 2X F l u i d
r e c om m e n d e d f r en c l os e d g e a r s a n d e x p o s e d worm gears. . Should ambient tempe ratur es be extremely low o r h i g h o r s h o ul d a n y u n c e r t a in t y e x i s t a s to
AGMA STANDARD SPECIFICATION FOR LUBRICATION OF INDUSTRIAL ENCLOSED GEARING AGMA
T YP E O F O I L :
250.02
EC.
1955
. Shall be high-quality, well-refined, petroleum oil. b. Shall be noncorrosive to gea rs, to ball, roller a nd sleeve bearings. . Shall be neutral in reatt ion , free from g ri t or abrasiveness, have good defoaming properties and good oxidation resistance. d. Shall be stra igh t mineral oil with following exceptions: (1 ) Fo r worm gears, addition less tallow, is desirable.
3% to 10% animal fa t such as acid-
(2) Special additives are permitted in applications where speeds, loads or temperatures are abnormal. VISCOSITY:
. Viscosity Index (Dean
Davis)
f 30 minimum i s allowed fo r ordi-
nary applications. Where operating temperatures vary more than 80° F., a viscosity index of 60 minimum i s desired. Oils meeting AGMA 7 comp and 8 comp mus t have a minimum viscosity index f 90 . Viscosity mus t be within t he rang es shown below:
V IS C O SI TY R A N G E F OR V A R I O U S A Visc osity Range UV Sec on ds
AGMA Number
2
100°F.
210°F.
A L UB RI CA NT S Texaco Oils Recommended Against This Specification
180 to 240
Regal
280 to 360
Regal PC R&O
490 to 700
Regal
R&O
Regal
R&
to 1000
R&
Regal H R&O Regal
R&O
cornp*
Honor Cylinder Oil
comp*
650T Cylinder Oil
TENTATIVE AGMA STANDARD SPECIFICATION MILD EXTREME PRESSURE LUBRICANTS FOR I N D U S TR I A L E N C L O S E D G E A R I N G AGMA
SCOPE:
252.01 - M A Y
1959
a. Applicableito following types of gearing. Helical Herringbone tr
ii
t e
Spira l Beve Spur b . N o t a p pl ic a b le t o w o r m g e a r i n g ( C o n s u l t M a n u f a c t u r e r s )
TYPE O F O I L :
h a l l b e a m i l d e x t r e e p r e s s u r e o il w i t h f o l l o w i n g c h a r a c t e r i s t ic s . a. No separation of oil and additive. b . H a v e m a x i m u m r e s i s ta n c e t o f o a m i n g u n d e r n o r m a l operating conditions. c.
N o n - c o r r o si v e t o m e t a l s e n c o u n t e r e d e v e n i n p r e s e n c e o f m o i s t u r e .
d . H a v e m in im u m T i m k en E P t e s t
30 pounds load.
e . C o n t a i n n o d i r t , a b r a s i v e o r o t h e r d e l e te r i o u s m a t e r i a l s . f . S u ff ic i en t ly s t a b l e o g i v e n o r m a l s e r v ic e l i f e i n A G M A S t a n d a r d G e a r s o p e ra t in g a t t e m p e r a t u r e s u p t o 1 6 0 ° F
VISCOSITY:
a . H a v e m i n i m u m V i s c o si t y I n d e x f 6 0 . . V i s c o s it y of v a r i o u s g r a d e s u s t b e w i t h i n t h e r a n g e s sh o w n b e lo w :
V I SC O S IT Y R A N G E O F A
Mild EP Lubricant Number AGMA
Viscosity Ranges 100°F.
A L U B R IC A NT S
SUV Seconds
Texaco Oils Meeting AGMA Standard 252.01
280-400
Meropa Lubricant
400-700
Blend Meropa
