777F Off-Highway Truck: Rear Suspension (Cylinder) - Purge and Charge

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. Check the dimensions of the rear suspension cylinders. Compare these dimensions to the dimensions that were recorded previously. The suspension height will be different for each machine.

When the rear suspension cylinders are properly charged, the left rear suspension cylinder will not show as much chrome as 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.

Purge the Suspension Cylinder of Oil and of Nitrogen

Table 1

Tools Needed
Part Number	Description	Qty
175-5507	Nitrogen Charging Group	1
175-7410	Nitrogen Charging Fitting Gp	1
1S-8938	Charging Chucks	2

WARNING: 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.

(1) Valve cap(2) Charging valve



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



1. Remove valve caps (1) from the charging valves (2) that are located on each of the rear suspension cylinders. Turn the tee handles on the 1S-8938 Chuck counterclockwise in order to ensure that charging valves (2) will not open during installation.

2. Install the charging hoses to charging valves (2) with 1S-8938 Chuck . The charging hoses will be used to drain oil into an approved container.

3. Turn the swivel nut counterclockwise on charge valve (2) to open charge valve (2) .Note: The valve core is to aid in charging. The valve core is intended as a safety backup for charging valve (2) . The valve core is not intended as a primary seal. The swivel nut must be in a closed position prior to attaching the apparatus that is used for charging.

4. Turn the tee handle on the 1S-8938 Chuck clockwise in order to allow nitrogen to flow through charging valves (2) .Note: When the suspension cylinders have bottomed completely, leave the chucks in position for five minutes in order to allow pressure in the cylinders to equalize.

5. After the pressure has equalized, turn the check valves on the 1S-8938 Chucks counterclockwise to close charging valves (2) .

6. Remove the charging hoses from charging valves (2) . Attach the charging hoses to the rest of the 9U-5617 Oil Refill Pump . Place the ends of the charging hoses into an approved container or into the filler tube of the 9U-5617 Oil Refill Pump . Cycle some oil in order to ensure that the charging hoses are full of clean oil. Attach the 1S-8938 Chucks to charging valves (2) .

Determining Correct Pin to Pin Dimension

Pin to pin dimension



1. Verify the collapsed pin to pin dimension of 915 mm (36 inch). Position a steel ruler or a thin strip of sheet metal on both of the suspension cylinders in order to measure the rod extension. A magnet can be used in order to mount the measuring tool. Possible magnets include the magnetic plug for the final drive and the magnetic base for a dial indicator. The measuring tool can also be mounted with the clamps that are used to mount the dust boot. The measuring tool should extend downward. The measuring tool should be parallel to the centerline of the suspension cylinder.Note: Measure the outside ambient temperature and the temperature of the service shop. If this temperature difference is greater than 20°F, you will need to adjust the final pin to pin dimension of 1030 mm (40.6 inch). Add 2.54 mm (0.10 inch) to the pin to pin dimension for each 10°F of temperature difference.
   Example
   Note: Estimate the temperature difference to the nearest 5.5°C (10°F).
   Temperature of the service shop ... 10°C (50°F)
   Outside ambient temperature ... -40°C (-40°F)
   Difference in temperatures
   10°C (50°F) − (−40°C (−40°F)) = 50°C (90°F)
   Additional length for temperature compensation
   50°C (90°F) × 2.54 mm (0.10 in) ÷ 5.5°C (10°F) = 23.1 mm (.90 in)
   Corrected guidelines for the nitrogen charging procedure
   1030 mm (40.5 in) + 23.1 mm (0.90 in) = 1053.1 mm (41.43 in)

Oil Charging Procedure

Table 2

Tools Needed
Part Number	Description	Qty
8T-5320	Hydraulic Test Group	1
9U-5617	Oil Refill Pump  (1)	1
1S-8938	Charging Struts	2

( 1 )

This is optional.

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.

Pressure tap for the rear brake slack adjuster

Note: Use SAE 10W oil with a service classification of CH for the oil charging procedure.


1. Ensure that the cylinders have been purged of nitrogen and oil. The collapsed pin to pin dimension is 915 mm (36 inch).Note: Assemble an appropriate charging hose from the 8T-5320 Hydraulic Test Group .

2. Connect the charging hose to the 1S-8938 Chucks .

3. Connect charging hose to the pressure tap for the rear brake adjuster. Refer to Illustration 4 in order to view the location of the pressure tap. The slack adjuster is located on top of the rear axle housing.

4. Connect 1S-8938 Chucks to charging valve (2) .

5. Start the machine.

6. Apply the manual retarder.

7. Turn the tee handle on the 1S-8938 Chucks clockwise to open charging valve (2) .

8. Turn the swivel nut counterclockwise on charge valve (2) to open charge valve (2) .

9. Inject oil into the suspension cylinder until the correct pin to pin dimension is reached. If necessary, open the second charging valve (2) and add oil until oil flows through the second charge valve (2) without air. The correct pin to pin dimension is 928 mm (36.5 inch) prior to any required adjustments due to temperature.

10. Turn the tee handles on the 1S-8938 Chucks counterclockwise to close charging valves (2) .

11. Turn the swivel nut clockwise on charge valve (2) to close charge valves (2) .

12. Disengage the manual retarder.

13. Shut down the machine.

14. After the charge pressure has returned to zero, use the quick couplers to remove the charging hoses.

Oil Charging Procedure That Uses The Optional 9U-5617 Oil Refill Pump

Table 3

Tools Needed
Qty	Part Number	Description
1	9U-5617	Oil Refill Pump
2	1S-8938	Chucks

WARNING: 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.

Typical example of the setup for the oil charging procedure

Correct oil level (3) Reference line (4) Reference line on the cylinder (5) Reference line for the oil charging procedure (6) Reference line for the nitrogen charging procedure(7) Reference line for the nitrogen charging procedure

Note: Use SAE 10W oil with a service classification of CH for the oil charging procedure.


1. The charging hoses and the 1S-8938 Chucks should be connected to charging valves (2) . Open the shutoff valves. Adjust the air pressure on the regulator. The air pressure must not exceed 860 kPa (125 psi).

2. Turn the check valves on the 1S-8938 Chucks clockwise to open up charging valves (2) .

3. Inject the oil into the suspension cylinder until reference line (5) lines up with reference line (4) on the cylinder.Note: If one suspension cylinder reaches reference line (5) before the other suspension cylinder, close the shutoff valve for that suspension cylinder. Continue injecting oil into the other suspension cylinder until the reference line (4) on the cylinder lines up with reference line (5) .

4. Close the shutoff valves. Turn off the air pressure at the regulator. Turn the check valves on the 1S-8938 Chuck counterclockwise to closes charging valves (2) .

5. Turn swivel nut (A) clockwise to close charging valves (2) .

6. After the pressure has returned to zero, use the quick couplers to remove the charging hoses. If the quick couplers are not available, you may need to remove the 1S-8938 Chucks .

Nitrogen Charging Procedure

Table 4

Tools Needed
Part Number	Description	Qty
175-5507	Nitrogen Charging Fitting Gp	1
175-7410	Nitrogen Charging Group	1
1S-8938	Charging Chucks	2

WARNING: Dry nitrogen is the only gas approved for use in the suspension cylinders. Charging the suspension cylinders with oxygen gas will cause an explosion. This danger will not happen if nitrogen cylinders with standard CGA (Compressed Gas Association, Inc.) Number 580 Connections are used. When you order nitrogen gas, be sure that the cylinders are equipped with CGA No. 580 Connections. Do not use color codes or other methods of identification to tell the difference between nitrogen cylinders and oxygen cylinders.Never use an adapter to connect your nitrogen charging group to a valve outlet used on both nitrogen, oxygen or other gas cylinders. Be sure you use dry nitrogen (99.8% purity).

Typical example of the setup for the nitrogen charging procedure

1. Attach the 175-5507 Nitrogen Charging Group and the 175-7410 Nitrogen Charging Fitting Gp to the quick couplers or to the charging valves at each suspension cylinder.Note: To prevent oil flow into the charging hoses, do not open the charging valves at this time.

2. Open the shutoff valves in order to allow nitrogen to flow to the 1S-8938 Chucks .

3. Adjust the nitrogen regulator in order to provide 2020 kPa (293 psi).

4. Turn the tee handles on the 1S-8938 Chucks clockwise to open up charging valves (2) . Nitrogen will flow to charging valves (2) .The correct pressure is 2020 kPa (293 psi).

5. Turn the swivel nut counterclockwise to open charging valves (2) .

6. Allow nitrogen into the suspension cylinder until the correct pin to pin dimension is achieved. The correct pin to pin dimension is 1030 mm (40.6 inch).Note: If one suspension cylinder has extended to the correct amount before the other suspension cylinder, close the shutoff valve for that suspension cylinder. Continue allowing nitrogen into the other suspension cylinder until the correct extension has been reached.

7. After the suspension cylinders have extended to the proper length, close both of the shutoff valves.

8. Turn the tee handles on the 1S-8938 Chucks counterclockwise.

9. Turn the swivel nut clockwise on charge valve (2) to close charging valves (2) .

10. Turn off the nitrogen pressure at the supply tank. Remove the 175-5507 Nitrogen Charging Group and the 175-7410 Nitrogen Charging Fitting Gp .

11. Install the valve caps to the charging valves. Torque the valve caps to 2 to 3 N·m (18 to 26 lb in).

12. After the suspension cylinders have been properly charged, measure the pin to pin dimension. Record this value. Use these recorded dimensions as a reference when you inspect the rear suspension cylinders.

13. Operate the machine through a cycle and check the ride height. If the ride height has changed, adjust the nitrogen pressure until the correct ride height is reached. Record the final ride height and pressure.

Worksheets

Table 5

Model Of The Machine		Date
Serial Number		Service Meter Hours
Component Damage

Table 6

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 7

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).

MARYGAR

777F Off-Highway Truck: Rear Suspension (Cylinder) - Purge and Charge 2012-12-02T11:00:00-08:00 Rating: 4.5 Diposkan Oleh: Unknown