02 Transmission System LG933L

�� Chapter Chapter 3 Torque orque converter converter & gearbox gearbox

Chapter Chapter 3 Torque conve converter rter & gearbox gearbox

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RELIABILITY IN ACTION

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All parts(including torque converter, converter, gearbox, drive shaft) between power device(engine) and drive device(axle) of construction equipment are called drive system.


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1.Overview LG933L adopts YJ315LGYJ315LG-1 -1 hydraulic hydrau hydraulic lic torque converter. converter.


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2.Structure The basic hydraulic torque converter is mainly composed of pump impeller 1, guide wheel 2 and turbine 3, and the sealed annular working chamber formed by said components is the circulation passage of the working fluid. The shape of the working chamber within the cross section cut by revolving axis (namely, the axial surface) is called a circulation circle. The circulation circle of the torque converter forms to completely symmetrical part by taking rotating shaft as centre line. The largest diameter of the portion passed by the working fluid in the circulation circle is called the effective diameter of the circulation circle.


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2.Torque converter operating principle During operation of the hydraulic torque converter, the engine drives the pump impeller to rotate, and the torque of the engine is exerted to the pump impeller. The working fluid in the pump impeller is driven to rotate by the blades of the pump impeller during rotation. The fluid performs circular motion around the axis of circular motion called trans ort motion) while executes relative motion from the inner edge of the blade to the outer edge thereof along the passage among the blades, and combination of the two motions forms absolute motion; meanwhile, the pressure on the outer edge of the pump impeller is higher and on the inner edge is lower, the difference of which depends on the radius and rotation speed of the pump impeller.


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The working fluid bears the effect of blades of pump impeller and gains certain kinetic energy and pressure energy when departing the pump impeller so as to convert the generated mechanical energy into fluid energy of working fluid (kinetic energy and pressure energy). he high-speed oil flow from the pump impeller enters the turbine 3 through a blade-free area from by housing wheel and impacts the turbine blades to rotate the turbine and enable the turbine shaft to obtain certain torque for overcoming the external resistance and starting work .


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While changing the momentum moment of the fluid, the guide wheel further changes the energy form of the fluid, namely, the transition from the pressure energy of the fluid into the kinetic energy thereof, or the converse transition. Generally speaking, it changes the pressure energy of the fluid into kinetic energy.


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Power from torque converter is transmitted to gearbox through drive shaft.

1-drive shaft

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4.Oil– 4.Oil –way way ①oil oil--way structure of speedspeed-control

pump

1-temperature sensor �

2-inlet oil pipe of radiator for drive oil 3-inlet oil pipe of speedspeed-control pump

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4-oil filter 5-pipe between pump and filter

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6-speedspeed-control pump �


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4.Oil– 4.Oil –way way

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② oil oil--way structure of working pump

1-inlet oil pipe of torque converter(belonging to oiloil-way structure of speedspeed-control pump) 2-working pump 3-inlet oil pipe of working pump 4-outlet oil pipe of working pump

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1.Overview A. Function of gearbox ①. reduce the speed and increase

the torque； ②. Make the loader have a good

self--adaptability； self ③.realize neutral, make it easy to

start and stop when engine is working； ④.working with torque converter, and

enlarge the range of output power and speed； ⑤. Enable loader backward

movement .


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B. Classification of gearbox According to Control Mode: ①. Power Shifting Gearbox ； ②. Manual Shift Gearbox ； ③.Auto shift gearbox.

Power Shifting Gearbox conclude： ①. AxisAxis-fixed Gearbox ②. Planetary Gearbox


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2.BYD4208 gearbox A、Type BYD4208 is AxisAxis-fixed, constant mesh, hydraulic or shift fork gearbox. B.Feature Simple and compact structure, Reliable work, convenient operation, high transmission efficiency and long serve life.


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3.Structure

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Main structure of BYD4208 as following： 1-reverse shaft assembly 2-input shaft assembly

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3-middle shaft assembly 4-output shaft assembly 5-shift fork shaft

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6-shift fork 7-clutch of gear II 8-clutch of gear I

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9-clutch of reverse gear

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A、clutch

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①structure

All clutch of this gearbox are same basically as shown in right figure: 1-shaft

2-shell

3-piston

4-driving disc

5-driven disc 7-ball

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6-spring

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8-oil channel

9-driven gear

1010-seal ring

11--piston ring 1211 12- valve plate 13--oil port for lubricating oil 13 bearing

1414-

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1515-driving gear


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②working principle

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When no pressure oil flows into cylinder, there is a small space between driven disc and driving disc, so all disc keep their state of motion; ��

when pressure oil flows into the cylinder of clutch, the piston is

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pushed left to make all discs hug tightly and rotate in the state of driving disc; when the pressure oil is cut off, the piston return at the action

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of the springs, and meanwhile release all discs.


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Clutch assembly of gear I Clutch assembly of gear I is fixed on input shaft.


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Clutch assembly of gear II Clutch assembly of gear II is fixed on the middle shaft�


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Clutch assembly of reverse gear Clutch assembly of reverse gear is fixed in shaft of reverse gear.


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B. The arrangement of all shaft assembly in the gearbox

1-input shaft assembly 2-reverse gear shaft assembly

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3-middle shaft assembly 4-output shaft assembly

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C. Output shaft assembly ①formation

1-rear output flange 2-rear cover of output shaft 3-P bearing

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4-sliding bearing 5-highhigh-speed output gear 6-sliding sleeve 7-output shaft 8-lowlow-speed output gear


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②shifting fork mechanism assembly

1-shifting fork 2-paper spacer 3-shifting fork bracket 4-shifting fork shaft

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③operating principle

The sliding bearings 1 cause gear 2 and 4 move relative to the shaft 3. Gear 2 and 4 have same modules as gear in the shaft 3. and they can mesh tightly with sliding sleeve 5. Shifting fork 6 gets stuck in the shifting fork groove in the sliding sleeve. There is a highhigh-low speed control rod, and this rod control the shift fork 6 through the shaft 7 and make it can move in a certain range. �

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When sliding sleeve meshes with gears in the boss of the gear 2 and gears in the shaft 3, the wheel loader drives at high speed. When sliding sleeve meshes with gears in the boss of the gear4 and gear in the shaft 3, the wheel loader drives at low speed.

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D、transmission line ①forward gear I

Transmission line as following


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②forward gear II



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③forward gear III



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④forward gear IV



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⑤reverse gear I



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⑥reverse gear II



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E. SpeedSpeed-control valve Speed--control valve is the device Speed which controls the direction of pressure oil and control the motion of the clutch making the vehicle drive at the speed and in the condition you choose.

①Formation

1-sealant 2-core of the speedspeed-control valve

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3-valve body 4-paper washer

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5-cutting valve 6-bottom plate 7-paper washer

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8-gear positioning device �

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①Arrangement of oil ports in the

speed--control valve speed Cavity A is links with oil inlet(oil inlet is links with combined valve of torque converter). Cavity B links with oil passage of �

speed--control valve speed Cavity D links to the clutch of gear I

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Cavity E links to the clutch of gear II

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Cavity F links t the clutch of reverse gear

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②Cutting valve（spare）

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When the brake pedal is pressed down, brake pressure air presses the valve core of the cutting valve move, and cuts the passage between cavity A and B, so the pressure oil can’t flow into speedspeed-control oil passage, therefore there is no power output. �


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Speed--control schematic diagram ③Speed

1-filter 2-speedspeed-control valve 3-speedspeed-control pressure selective valve 4-pressure limit valve of outlet 5-pressure limit valve of inlet 6-speedspeed-control valve 7-cutting valve


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1. Notes for assembly

A. End cover of gear II can’t change with it of gear I of reverse gear.


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B. Adjusting nut of clutch assembly


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C. When assemble, you should ensure the input shaft of gearbox and output shaft of torque converter coaxial, same as the output shaft of gearbox and input shaft of front and rear axle.


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2. Notes for operation： A. You should pay attention to the pressure indictor of speedspeed-control oil （1.2 1.2--1.5MPa） and lubrication oil （0.15 0.15--0.30MPa） at time, no

condition of exceeding the range is permitted�


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B. The speedspeed-control rod and even the whole speedspeed-control mechanism should be flexible, no binding is permitted, position should be precise when change gear.

Scheme 1：high high--low speedspeed-control mechanism. Scheme 2：gear speedspeed-control mechanism. C. When the brake pedal is pressed down, the vehicle mustn’t drive even in condition of strongest power of the engine.

图一

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D. Hand brake mechanism should be adjusted well to make sure its work reliably.


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①Change the drive oil at time of the first 50hours’ use, and change again at 500hours’ use,

from then on, change every 1000hours.

②Clean the filter of drive oil at time of the first 50hours’ use, and from then on ,clean it every

500hours. Pay attention to that whether there is aluminum swarf, swarf, copper swarf swarf,, iron swarf when change drive oil, so according to the result you can find whether C&T work well. If you find copper swarf in the oil, you should check the gearbox, and if aluminum swarf, swarf, check torque converter.

③Check whether the oil level is enough, whether there is abnormal noise in the gearbox,

whether the knots are loose, and whether there is leakage, check whether the temperature and pressure of drive oil in the normal range.


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�� 1、Failures：the oil pressure is low excessively even the pressure is zero.

fault judgment and troubleshooting: ①lack for oil, pump sucks air.（add oil） ②blockage in filter.（clean or replace the filter） ③failure of the pump. (replace the pump) ④failure of the main pressure valve in adjuster valve.（repair the speedspeed-control pressure valve） ⑤leakage in speedspeed-control valve.（check, repair) ⑥leakage as result of failure of seal of clutch or gasket ring in the end of shaft where there is oil inlet port. （replace gasket ring）；

one-way valve in the clutch. ⑦miss of the ball of the one-


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�� 2、 Failures：oil pressure is high excessively

fault judgment and troubleshooting: ①failure of main adjuster valve in pressure reducing valve.（check or repair) ②something outside enters oiloil-passage to make a blockage.(clean and rip it) ③the oil is not fit fit((change the oil for standard oil) oil) ； ④failure of the sensor of the pressure oil 。


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�� 3、 Failures：oil temperature is high excessively

fault judgment and troubleshooting: ①blockage in radiator (clean the radiator）； ②there is some water in oil.（check the pipe and replace the oil) ③lack for drive oil in the gearbox（add oil）； ④the gear is not suitable when working.（choose low gear）； ⑤hand brake is locked and return bragging seriously.(adjust the brake) ⑥the discs can’t part absolutely or they hug together.(replace the discs)


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02 Transmission System LG933L

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