sistema de Suspension.pdf

Service Training MALAGA

777D Off Highway Truck SUSPENSION CYLINDER DURING COMPRESSION

VIII SUSPENSION. 1. 2. 3. 4.

Components Layout Operation Maintenance Testing & Adjusting Adolfo August 1997

777D Off Highway Truck

Page:

DURING COMPRESSION

SUSPENSION CYLINDER

CHAPTER : SUSPENSION

VIII1

777D Off Highway Truck

Page:

DURING EXTENSION

SUSPENSION CYLINDER

CHAPTER : SUSPENSION

VIII2

Page:

SUSPENSION CYLINDER

VIII3

BALL CHECK VALVE AND ORIFICE OPERATION

ROD

COMPRESSING

CENTERED

EXTENDING

777D Off Highway Truck

CHAPTER : SUSPENSION

HOUSING

Page: VIII4

REAR SUSPENSION CYLINDER

FRONT SUSPENSION CYLINDER

CHARGING VALVE

CHARGING VALVE

PISTON ORIFICES

GLAND

GREASE VALVE

WEAR RING

ORIFICE BALL CHECK VALVE

777D Off Highway Truck

TUBE

CHAPTER : SUSPENSION

BALL CHECK VALVE

Page: VIII5

SUSPENSION GAS VOLUME CHANGE UNDER PRESSURE

100 kPa (15 psi)

2050 kPa (300 psi)

777D Off Highway Truck

.095 LITER (.1 QUART) OF NITROGEN

CHAPTER : SUSPENSION

1.9 LITERS (2.0 QUARTS) LOW OIL

777D Off Highway Truck CHAPTER : SUSPENSION

FRONT SUSPENSION CHARGING SEQUENCE: Check for and eliminate any oil or nitrogen leaks.

Make sure the truck is empty and on level ground.

Put the open end of the suspension charging lines into an approved container. Open the charging valves and allow the oil and nitrogen to drain from the suspension cylinders into the container.

Position a thin strip of sheet metal on both suspension cylinders. Place a piece of masking tape on the sheet metal with the top edge of the tape even with the top of the spindle. Put a line across the tape 12.7mm (0.50in) below the top edge of the tape. Cycle some oil through the charging lines to fill them with clean oil.

Inject oil into the cylinders until each cylinder extends to the line made on the masking tapE.

To prevent oil flow from the suspension cylinders, adjust the nitrogen cylinder regulated pressure to 4150 kPa (600 psi). Charge the cylinders until the gauge blocks (and shims if required) can be installed between the spindle and the cylinder housing. Drain nitrogen from the suspension cylinders until the cylinder housings rest on the gauge blocks and the regulated nitrogen pressure is less than 2400 kPa (350 psi).

Adjust the regulated nitrogen supply to 2400 kPa (350 psi). Open the charging valves and allow the nitrogen to flow into the cylinders. Leave the valves open for approximately five minutes to allow the nitrogen charge pressure to equalize in the two suspension cylinders.

Remove the nitrogen charging group from the suspension cylinders and install the charging valve caps. Start the engine and raise the dump body to remove the gauge blocks.

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VIII6

777D Off Highway Truck CHAPTER : SUSPENSION

REAR SUSPENSION CHARGING SEQUENCE: Check for and eliminate any oil or nitrogen leaks.

Make sure the truck is empty and on level ground.

Put the open end of the suspension charging lines into an approved container. Open the charging valves and allow the oil and nitrogen to drain from the suspension cylinders into the container.

Position a thin strip of sheet metal on both suspension cylinders. Place a piece of masking tape on the sheet metal strips with the top edge of the tape even with the top of the cylinder housing. Put a line across the tape12.7 mm (0.5 in.) below the top edge of the tape. Place another piece of masking tape on the sheet metal strips and make a line on the tape 101.6 mm (4 in.) below the top of the cylinder housing. Put another line across the tape 114.3 mm (4.5 in.) below the top of the cylinder housing (adjust the lower two dimensions for temperature if required). Cycle some oil through the charging lines to fill them with clean oil.

Inject oil into the cylinders until each cylinder extends to the line made on the masking tape.

To prevent oil flow from the suspension cylinders, adjust the nitrogen cylinder regulated pressure to 2400 kPa (350 psi). Charge the cylinders with nitrogen until the top of the cylinder housing is located within the two lines made on the lower piece of masking tape. Leave the valves open for approximately five minutes to allow the nitrogen charge pressure to equalize in the two suspension cylinders. Remove the nitrogen charging group from the suspension cylinders and install the charging valve caps.

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VIII7

777D Off Highway Truck CHAPTER : SUSPENSION

LAB EXERCISES LAB B

FRONT SUSPENSION CYLINDER CHARGING WORKSHEET Machine Model _______777D_______________Date_____________________________________ Serial Number ___________________________ Service Meter Hours________________________

Oil Charge Dimension ____________

Nitrogen Charge Dimension Temperature Correction: Shop Temperature

10 C

Outside Temperature

-50 C Temperature Difference ________ = Shim Thickness ___________________

Temperature Difference X

Corrected Nitrogen Charge Dimension _______________

Nitrogen Charge Pressure _____________

Chrome Length Measurement After Gauge Block is Removed: *

Left Front _____________ Right Front ____________

Wiped Chrome Dimension After Operation:

Left Front _____________ Right Front ____________

* dimension between top of spindle and bottom of cylinder housing

SHIMS FOR TEMPERATURE CORRECTION

Truck Model

Shim Thickness mm/5.5 °C (in./10 °F)

776D/777D

2.54mm(0.10in)

777D Off Highway Truck CHAPTER : SUSPENSION

POSTTEST SUSPENSION SYSTEM POSTTEST

Directions: Modified True/False. If a question is false, underline or circle the word or words that make the statement incorrect and replace with word(s) to make the statement correct.

Example:

F

1. This is an engine class.

1. After the front suspension cylinders are charged with nitrogen and the gauge blocks are removed, the exposed chrome length will usually be less than the gauge block dimension.

2. Before charging the suspension cylinders with nitrogen, the nitrogen charge hoses must be pressurized to prevent high pressure oil in the cylinders from flowing into the nitrogen charge hoses.

3. Always charge two suspension cylinders at the same time.

4. If the truck is in the shop and the temperature outside is 16 °C (60 °F) colder, the suspension cylinder nitrogen charge length will be greater.

5. If the truck is in the shop and the temperature outside is 16 °C (60 °F) colder, the suspension cylinder oil charge length will be greater.

6. Suspension cylinders will compress faster than they extend because of the ball check valve located in the cylinder rod.

7. A blue/black patch of stain on the suspension cylinder chrome is caused by heat between the rod and the wear band. The stain can be polished off and does not affect the wear life of the suspension cylinder.

8. Greasing the front suspension cylinders too fast can cause the wiper seal to be forced out of the bottom of the cylinder housing.

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VIII9