Procedimiento de Carga de Nitrogeno

Service Information System

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Instrucción Especial Servicing the Suspension Cylinders for Off-Highway Trucks{0756, 7200, 7201, 7201, 7201, 7213, 7213} Número de medio -REHS4445-04

Fecha de publicación -17/09/2014

Fecha de actualización -17/09/2014

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Servicing the Suspension Cylinders for Off-Highway Trucks {0756, 7200, 7201, 7201, 7201, 7213, 7213} SMCS - 0756-542; 7200-542; 7201-542; 7213-542 Off-Highway Truck/Tractor: 769D (S/N: BBB1-UP; 5TR1-UP; 5SS1-UP) 770 (S/N: BZZ1-UP) 770G (S/N: ECM1-UP) 772 (S/N: RLB1-UP) 772G (S/N: LTS1-UP) 773D (S/N: NBJ1-UP; 7ER1-UP; 7CS1-UP) 773E (S/N: BDA1-UP; KEG1-UP; ASK1-UP) 773F (S/N: EED1-UP; EXD1-UP) 777D (S/N: AGC1-UP; FKR1-UP; 3PR1-UP) 777F (S/N: JRP1-UP; JXP1-UP) 777G (S/N: T5A1-UP; TNM1-UP; RDR1-UP; T4Y1-UP) Quarry Truck: 771D (S/N: BCA1-UP; 6JR1-UP; 6YS1-UP) 773G (S/N: MWH1-UP; JWS1-UP; T5S1-UP; T5T1-UP) 775D (S/N: 6KR1-UP; 8AS1-UP) 775E (S/N: BEC1-UP) 775F (S/N: EYG1-UP; DLS1-UP) 775G (S/N: T5F1-UP; RFM1-UP; MJS1-UP; T5W1-UP)

Introduction This Special Instruction contains the information and the procedure that should be used for purging the oil and nitrogen from the suspension cylinders. Also, this document contains an incremental charging procedure for the oil and nitrogen that is used in the suspension cylinders on off-highway trucks. Read the entire document before you proceed with any work on the suspension cylinders. Trucks may have different weight configurations due to differences in dump body, liners, engines, custom attachments. The different weight configurations can cause varied carry pressures. For suspension issues regarding the large off-highway trucks refer to Special Instruction, SEHS9411, "Servicing the Suspension Cylinders for Off-Highway Trucks". The suspension system on the machines consists of four suspension cylinders. When the suspension cylinders are charged with the proper amount of oil and nitrogen, the suspension system should provide: Better machine ride. Improved structural durability.

https://127.0.0.1/sisweb/sisweb/techdoc/content.jsp?calledpage=/sisweb/sisweb/productse... 29/03/2017


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Improved shock absorption and operator comfort. Reduced quality concerns on the suspension cylinders. Maintain intended levels of controllability. Better operating efficiency Increases the accuracy of the payload management system Note: These procedures are to maintain the correct suspension cylinder charge and the correct ride height.

Personal injury or death can result from sudden suspension cylinder movement. Sudden movement, up or down, can cause the clearance above your head to change rapidly. Read all warning labels on the suspension cylinders before servicing. Do not check the oil in the suspension cylinder until all the nitrogen pressure has been released. Do not, under any condition, remove valves, cover or plugs from the cylinder unless the rod is fully retracted and all the nitrogen pressure is released. Do not stand under the machine when testing or adjusting the suspension cylinders.

Personal injury or death can result from improper lifting or blocking. When a hoist or jack is used to lift any part or component, stand clear of the area. Be sure the hoist or jack has the correct capacity to lift a component. Install blocks or stands before performance of any work under a heavy component. Approximate weights of the components are shown. Clean all surfaces where parts are to be installed.

Important Safety Information



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The following information is an explanation of various labels that are found in this document. Warnings The warning label informs the technician that an injury or death can occur as a result of a condition that may exist. Notices A notice informs the technician that component damage can occur as a result of a condition that exists. Notes A note contains general information for the technician about the operation that is being performed. Proper repair is important to the safe operation and the reliable operation of this machine. This document outlines recommended procedures. Some of the procedures require special tools, devices, or work methods. Before you perform any repairs or before you perform any maintenance, read all safety information. Understand all safety information before you perform any repairs or before you perform any maintenance. Safety information is provided in this document and on the machine. If these hazard warnings are not heeded, bodily injury or death could occur to you or other persons. The "Safety Alert Symbol" that is followed by a "Signal Word" identifies a hazard. "DANGER", "WARNING", and "CAUTION" are "Signal Words".

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Illustration 1

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The signal word "WARNING" has the following meanings: Pay Attention ! Become Alert ! Your Safety Is Involved ! The message that appears under the safety alert symbol explains the hazard. Operations or conditions that may cause product damage are identified by "NOTICE" labels on the machine and in the service information. The person that services the machine may be unfamiliar with many of the systems on the machine. Use caution when you perform service work. Special knowledge of the systems and of the components is important. Before you remove any component or before you disassemble any component, obtain knowledge of the system and knowledge of the component. Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. The safety information in this document and the safety information on the machine are not all inclusive. You must determine that the tools, procedures, work methods, and operating techniques are safe. You must determine that the operation, lubrication, maintenance, and repair procedures will not damage the machine. Also, you must determine that the operation, lubrication, maintenance, and repair procedures will not make the machine unsafe.



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Basic Precautions

Improper operation, lubrication, maintenance or repair of this product can be dangerous and could result in injury or death. Do not operate or perform any lubrication, maintenance or repair on this product, until you have read and understood the operation, lubrication, maintenance and repair information. Always observe the list of basic precautions that follows:

Safety Signs Safety signs include the items that follow: signs, information plates and decals. Read all "Safety" signs on the machine before operating, lubricating, or repairing the machine. Understand all "Safety" signs on the machine before operating, lubricating, or repairing the machine. Replace any safety signs that are in the conditions that follow: damage, unreadable and missing.

Protective Equipment When you work around the machine, always wear protective equipment that is required by the job conditions. Protective equipment includes the items that follow: hard hat, protective glasses and protective shoes. In particular, wear protective glasses when you use a hammer or when you use a sledge hammer. When you weld, use the appropriate protective equipment that is required by the job conditions. Protective equipment for welding includes the items that follow: gloves, welding hood, goggles and apron. Do not wear loose clothing or jewelry that can catch on parts of the machine.

Mounting and Dismounting

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Illustration 2

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Use steps and handholds whenever you mount the machine. Use steps and handholds whenever you dismount the machine. Before you mount the machine, clean the step and the handholds. Inspect the step and handholds. Make all necessary repairs. Face the machine whenever you mount the machine and whenever you dismount the machine. Maintain a three-point contact with the step and with handholds. Note: Three-point contact can be two feet and one hand. Three-point contact can also be one foot and two hands. Do not mount a moving machine. Do not dismount a moving machine. Never jump off the machine. Do not try to mount the machine when you carry tools or supplies. Do not try to dismount the machine when you are carrying tools or supplies. Use a hand line to pull equipment onto the platform. Do not use any controls as handholds when you enter the cab or when you exit the cab.

Specifications for Cables, Chains, and Lifting Devices Use approved cables, chains, and lifting devices in order to lift components. Refer to the manufacturer's weight's in order to determine the application when you select the following items: cable, chain and lifting devices. When you lift a component, the lift angle is critical. Refer to the Illustration that follows in order to see the effect of the lift angle on the working load limit. Note: The lifting devices that are shown in this publication are not Caterpillar parts.



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Note: Ensure that the hooks are equipped with a safety latch. Do not place a side load on the lifting eyes during a lifting operation.

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Illustration 3 Lift angles for lifting slings.

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(A) The load capacity is 100% of the working load limit for the sling. (B) The load capacity is 86% of the working load limit for the sling. (C) The load capacity is 70% of the working load limit for the sling. (D) The load capacity is 50% of the working load limit for the sling.

Hot Fluids and Parts To avoid burns, be alert for hot parts on machines which have just been stopped and hot fluids in lines, tubes and compartments. Be careful when you remove filler caps, breathers, and plugs on the machine. Hold a rag over the cap or plug in order to prevent being sprayed by pressurized liquids. When the machine has just been stopped, the danger of hot fluids is greater.

Corrosion Inhibitor



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Corrosion inhibitor contains alkali. Avoid contact with the eyes. Do not allow corrosion inhibitor to contact the skin for extended periods of time. Avoid repeated contact with the skin. Do not drink corrosion inhibitor. In case of contact, immediately wash skin with soap and water. For contact with the eyes, flush the eyes with large amounts of water for at least 15 minutes. Seek medical attention.

Batteries Do not smoke when an inspection of the battery electrolyte level is made. Never disconnect any charging unit circuit or battery circuit cable from the battery when the charging unit is operating. A spark can cause an explosion from the flammable vapor mixture of hydrogen and oxygen that is released from the electrolyte through the battery outlets. Do not allow battery electrolyte to make contact with the skin or with the eyes. Battery electrolyte is an acid. In case of contact with battery electrolyte, immediately wash the skin with soap and water. For contact with the eyes, flush the eyes with large amounts of water for at least 15 minutes. Seek medical attention.

Pressurized Items 1. Always use a board or a piece of cardboard when you check for a leak. Leaking fluid under pressure can penetrate body tissue. Fluid penetration can cause serious injury and possible death. A pin hole leak can cause severe injury. If fluid is injected into your skin, you must get treatment immediately. Seek treatment from a doctor that is familiar with this type of injury. 2. Relieve all pressure in air, oil, or water systems before any lines, fittings, or related items are disconnected or removed. Always make sure that all raised components are blocked correctly. Be alert for possible pressure when you disconnect any device from a system that utilizes pressure. 3. Fuel lines that are damaged and fuel lines that are loose can cause fires. Lubrication lines that are damaged and lubrication lines that are loose can cause fires. Hydraulic lines, tubes, and hoses that are damaged can cause fires. Loose hydraulic lines, tubes, and hoses can cause fires. Do not bend or strike high-pressure lines. Do not install lines which have been bent or damaged. Check lines, tubes, and hoses carefully. Do not use your bare hand to check for leaks. If fluids are injected into your skin, you must get treatment immediately. Seek treatment from a doctor that is familiar with this type of injury. 4. Pressure air or water can cause personal injury. When pressure air or water is used for cleaning, wear a protective face shield, protective clothing, and protective shoes. The maximum air pressure for cleaning purposes must be below 205 kPa (30 psi). When you use a pressure washer, keep in mind that the nozzle pressures are very high. The nozzle pressures are frequently above 13790 kPa (2000 psi). Follow all of the recommended practices that are provided by the manufacturer of the pressure washer.

Machine Preparation Before you service the suspension cylinders, the dump body must be empty. Verify that the body is clean and does not contain any carryback material. Ensure that the fuel tank is full of fuel. Position the machine on level ground. Coast the machine to a gentle stop without using the brakes. A sudden stop will alter the amount of exposed chrome. A sudden stop will also invalidate the information



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that is used to determine if the machine needs to be serviced.

Visual Inspection A visual inspection of each suspension cylinder is the first step in the analysis of a problem. Make sure that the machine is on level ground. Do the inspection on an empty machine while the engine is stopped. Check each suspension cylinder for oil leaks around the seals and around the valves. Check each suspension cylinder for nitrogen leakage. A nitrogen leak is difficult to detect. A solution that consists of soap and of water can be used to detect leaks. Make sure that there is no leakage around the valve cores and around the valve bodies. Make sure that the valve caps are in place. Make sure that the valve caps are tightened to the correct torque of 2 N·m (17.70 lb in) to 3 N·m (26.55 lb in). Check for leakage at the O-rings that are located under the manifold and under the pressure sensor. Check for leakage at the O-rings that are located under the protective plates that are on the head. These protective plates cover some of the head bolts in order to prevent removal of the head while there is pressure in the suspension cylinder. Friction between the rod and the lower wear band may cause a dark stain to appear on the chrome of the suspension cylinder. This stain does not affect the wear life of the suspension cylinder. You can polish the chrome in order to remove this stain. Eventually, the wear band should become soaked by oil and by grease and the blackening should decrease.

Conditions for Servicing Service for the suspension cylinder is recommended when any of the following conditions exist: A fault code will be displayed on the Vital Information Management System (VIMS), if the suspension cylinder is fully compressed (If equipped with VIMS). Suspension cylinder shows signs of leakage. The weight of the truck changes more than 22241 N (5000 lb). The ride is rough or the struts are at full extension when the truck is empty. The suspension cylinder pressures vary 345 kPa (50 psi) or more in comparison to the other side when the truck is empty. Refer to ""Machine Preparation" ". Compare the left front to the right front and the left rear to the right rear. Do not compare the front to the rear. The ride height of each cylinder is not within ± 13 mm (± .5 inch) of the correct height of that vehicle. This is only for a quick reference. These numbers should only be used if there are no records of lengths of the ride height from the past. Use the recorded data from other similar trucks to charge suspension cylinders, if the data is available. Refer to ""Machine Preparation" ". Refer to the Operation and Maintenance Manual, "Maintenance Interval Schedule" in order to check the



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suspension cylinders at the correct intervals. In the analysis of a problem in the suspension cylinders, each cylinder operates as a separate unit. Also, when the left rear cylinder is low, the right front cylinder will be high due to the shift in vehicle weight. The same conditions exist for the right rear cylinder and the left front cylinder.

Suspension Cylinder Oil Requirements Table 1 Required Oil Cat TDTO SAE 10W

Charging Tools Table 2 Charging Tools Item

Part Number

Description

1

9U-5617

Oil Refill Pump

2

7S-5106

Chuck

3

9U-5674

Hose As

4

1S-8941

Hose As

5

162-4147

Hose As

6

8S-4600

Fitting

7

8S-1506

Coupling As

8

162-4146

Regulator

9

1S-8938

Chuck

10

7S-5106

Chuck

11

8T-0859

Pressure Gauge

12

8S-4599

Coupling As

13

2S-5244

Fitting

14

1S-8937

Needle Valve

15

2D-7325

Pipe Tee



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16

1S-8941

Hose As

17

8S-7169

Coupling

18

1S-8941

Hose As

19

7S-5106

Chuck

20

175-6857

Hose As

21

2D-7325

Pipe Tee

22

1S-8937

Needle Valve

23

5P-8998

Fitting

24

3D-8884

Elbow

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Illustration 4

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(1) 9U-5617 Oil Refill Pump (2) 7S-5106 Chuck (3) 9U-5674 Hose As



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(4) 1S-8941 Hose As

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Illustration 5

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175-5507 Nitrogen Charging Group (5) 162-4147 Hose As (6) 8S-4600 Fitting (7) 8S-1506 Coupling (8) 162-4146 Regulator (9) 1S-8938 Chuck (10) 7S-5106 Chuck (11) 8T-0859 Pressure Gauge (12) 8S-4599 Coupling (13) 2S-5244 Fitting (14) 1S-8937 Needle Valve



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(15) 2D-7325 Pipe Tee (16) 1S-8941 Hose As

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Illustration 6 175-7410 Nitrogen Charging Fitting Gp

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(17) 8S-7169 Coupling (18) 1S-8941 Hose As (19) 7S-5106 Chuck (20) 175-6857 Hose As (21) 2D-7325 Pipe Tee (22) 1S-8937 Needle Valve (23) 5P-8998 Fitting (24) 3D-8884 Elbow

175-7410 Nitrogen Charging Fitting Gp is used with 175-5507 Nitrogen Charging Group in order to charge two suspension cylinders at the same time. 8T-0859 Pressure Gauge is used to check that the



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cylinder pressure before the charging procedure is performed.

Fabrication of Charge Block

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Illustration 7 Illustration of FT1680 Gauge Block

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(A) 215 ± 0.5 mm (8.50 ± 0.02 inch) (B) 170 ± 0.5 mm (6.69 ± 0.02 inch) (C) 8 ± 1 mm (0.3 ± 0.04 inch) (D) 50 ± 2 mm (2.0 ± 0.08 inch) (E) 40 ± 2 mm (1.6 ± 0.08 inch) (F) 25 ± 1 mm (1.0 ± 0.04 inch)

1. Using SAE 1020 steel, fabricate two gauge blocks. Refer to Illustration 7 for dimensions. Table 3



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Front Suspension Cylinders FT1680 Gauge Block Height Dimension (A) And Height Dimension (B) Model

Height Dimension (A)

769, 771

-

770, 772

-

Height Dimension (B) 170 ± 0.5 mm (6.69 ± 0.02 inch) 170 ± 0.5 mm (6.69 ± 0.02 inch)

773, 775

170 ± 0.5 mm (6.69 ± 0.02 inch)

776, 777

215 ± 0.5 mm (8.50 ± 0.02 inch)

NOTICE To protect the wiper seals on the front suspension cylinders from damage when the gauge blocks are inserted, make sure the gauge blocks include the chamfer.

Worksheets Table 4 Model Of The Machine

Date

Serial Number

Service Meter Hours

Component Damage Table 5 Front Suspension Cylinders Left

Right

Oil Leaks Nitrogen Leaks Length of Chrome Length of Clean Chrome



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Table 6 Temperature Compensation Temperature In The Service Shop Outside temperature Temperature Difference Added Length For Temperature Compensation (1) (1)

If the temperature difference is greater than 11°C (20°F), multiply the temperature difference by 2.54 mm (0.10 inch). Then, divide this amount by 5.5°C (10°F).

Table 7 Model Of The Machine

Date

Serial Number

Service Meter Hours

Component Damage Table 8 Rear Suspension Cylinders Left

Right

Oil Leaks Nitrogen Leaks Pin to Pin Dimension (1) (1)

This is the dimension between the center of the top mounting pin to the center of the lower mounting pin.

Table 9 Temperature Compensation Temperature In The Service Shop Outside Temperature Temperature Difference Added Length For Temperature Compensation (1) (1)

If the temperature difference is greater than 11° C (20° F), multiply the temperature difference by 2.54 mm (0.10 inch). Then, divide this amount by 5.5°C (10°F).

Rear Suspension (Cylinder) - Purge and Charge



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Perform Testing and Adjusting, "Visual Inspections" before you service the suspension cylinders. The machine must be on level ground when you inspect the suspension cylinder charge. The truck body must be empty. Coast the machine to a gentle stop without using the brakes. On certain models, when the rear suspension cylinders are properly charged, the left rear suspension cylinder will be at a higher pressure than the right rear suspension cylinder. The difference is due to the rigid frame and to the weight of the cab. Note: Both suspension cylinders must be charged at the same time. If only one suspension cylinder needs servicing, perform the procedure on both suspension cylinders. Table 10 Rear Suspension Cylinder Charging Specifications Model

Collapsed Pin to Pin Length

Oil Charged Pin to Pin Length

Nitrogen Charge Pressure (Reference Only)

769

776 mm (30.50 inch)

801 mm (31.50 inch)

1100 kPa (159.54 psi)

910 mm (36 inch)

771

776 mm (30.50 inch)

801 mm (31.50 inch)

1300 kPa (188.55 psi)

910 mm (36 inch)

1200 kPa (174.05 psi)

780 mm (31 inch)

1400 kPa (203.06 psi)

780 mm (31 inch)

2000 kPa (290 psi)

1015 mm (40 inch)

2150 kPa (312 psi)

1015 mm (40 inch)

2000 kPa (290 psi)

1030 mm (40.50 inch)

770

681 mm (27 inch) 706 mm (28 inch)

772

681 mm (27 inch) 706 mm (28 inch)

773

887 mm (35 inch) 912 mm (36 inch)

775

887 mm (35 inch) 912 mm (36 inch)

777

915 mm (36 inch)

928 mm (36.5 inch)

Nitrogen Charged Pin to Pin Length

Note: The amount of oil added to the suspension cylinder will increase the pin to pin dimension by 25.4 mm (1 inch). For example, the collapsed pin to pin dimension is 887 mm (35 inch) and 25.4 mm (1 inch) of oil is added. The oil charged pin to pin dimension is 912 mm (36 inch). The only truck that does not require 25.4 mm (1 inch) of oil is the 777. The 777 requires 12.7 mm (0.5 inch) of oil.



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Check the Height of the Rear Suspension Cylinders

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Illustration 8 Typical view of the rear suspension cylinder

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(A) Pin to pin measurement

1. Measure the pin to pin distance from the center of each pin. 2. Record the measured height of both rear suspension cylinders. 3. Compare the current recorded pin to pin dimension of the rear suspension cylinders to the previous recorded dimension of the rear suspension cylinders. Note: The suspension dimension will be different for each machine.

Purge the Suspension Cylinder of Oil and of Nitrogen Table 11 Tools Needed



Item

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Qty

Part Number

Description

1

175-5507

Nitrogen Charging Gp

1

175-7410

Nitrogen Charging Fitting Gp

2

1S-8938

Charging Chucks

A B

Note: When you work with the suspension charge valves, two chucks (B) will be needed.

Personal injury or death can result from sudden suspension cylinder movement. Sudden movement, up or down, can cause the clearance above your head to change rapidly. Read all warning labels on the suspension cylinders before servicing. Do not check the oil in the suspension cylinder until all the nitrogen pressure has been released. Do not, under any condition, remove valves, cover or plugs from the cylinder unless the rod is fully retracted and all the nitrogen pressure is released. Do not stand under the machine when testing or adjusting the suspension cylinders.

NOTICE Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates.

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Illustration 9 Typical view of the rear suspension cylinders and charging valves

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Illustration 10 View of area (A)

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(1) Valve cap (2) Charging valve (3) Swivel nut

Copyright 1993 - 2017 Caterpillar Inc. Todos los derechos reservados. Red privada para licenciados del SIS.

Wed Mar 29 15:14:00 CST 2017


Procedimiento de Carga de Nitrogeno

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