CP76 and CS76 Vibratory Compactors Propel System Caterpillar

Pressure Override Valve (Drum Propel Pump) - Test and Adjust

Usage:

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Personal injury can result from rotating and moving parts. Stay clear of all rotating and moving parts.
Never attempt adjustments while the machine is moving or the engine is running unless otherwise specified.
The machine must be parked on a level surface and the engine stopped.

Attach a "Do Not Operate" or similar warning tag to the start switch and controls before servicing, repairing, or making adjustments to the machine.

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Personal injury or death can result from sudden machine movement.
Sudden movement of the machine can cause injury to persons on or near the machine.

To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.

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Personal injury can result from hydraulic oil pressure and hot oil.
Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system.

Make sure all of the attachments have been lowered, and the oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of all fluids according to local regulations and mandates.

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Table 1
Required Tools
Tool	Part Number	Description	Qty
A ⁽¹⁾ B ⁽¹⁾	198-4234	Pressure Gauge Tool Gp	1
A ⁽¹⁾ B ⁽¹⁾	198-4236	Adapter Cable As	2
B	251-9600	Pressure Sensor 0 to 69000 kPa (0 to 10000 psi)	2
C	6V-9828	Cap As	1
D	6V-9507	Plug	1
D	4J-5477	O-Ring Seal	1
E	6V-9829	Cap As	2
F	6V-9508	Plug	2
F	6V-8397	O-Ring Seal	2
G	4C-6500	Digital Thermometer	1

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^( 1 )

Tool (A) is part of the 198-4240 Digital Pressure Indicator .

Drive the machine to a smooth, horizontal surface.

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Illustration 1	g01407630

Move propulsion lever (1) to the NEUTRAL position.

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Illustration 2	g01407609

Move parking brake switch (2) to the ON position.

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Illustration 3	g01407610

Move throttle switch (3) to the LOW IDLE position.

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Illustration 4	g01407660

Move engine start switch (4) to the OFF position.

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Illustration 5	g01408900

Remove bolts (5) and remove right cover plate (6) .

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Illustration 6	g01408904

Remove bolts (7) and remove left cover plate (8) .

Raise the cab. Refer to Disassembly and Assembly, KENR6413, "Cab - Tilt".

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Illustration 7	g01408980

Loosen set screw (9). Fully rotate the needle valve in the clockwise direction in order to prevent the parking brake from releasing.

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Illustration 8	g01411055
The Drum Pump is Shown From Left Side.

Disconnect balance line (10) and balance line (11) from drum pump. Use Tool (E) to cap ports. Use Tool (F) to plug the hoses.

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Illustration 9	g01411056
The Axle Pump is Shown From Left Side.

Disconnect electrical connector (12) for the axle interlock from the axle pump.

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Illustration 10	g01411058
The Drum Pump is Shown From Left Side.

Connect one Tool (B) to each of the following pressure taps:
- Forward pressure tap (14) on the drum pump
- Reverse pressure tap (13) on the drum pump

Lower the cab but do not install cover plate (6) or cover plate (8). Refer to Disassembly and Assembly, KENR6413, "Cab - Tilt".
Note: The cab mounting bolts must be installed and properly torqued before the engine is started.

Move engine start switch (4) to the START position. Release the switch when the engine starts.

Operate the engine at low idle for few minutes. Move throttle switch (4) to the HIGH IDLE position.

Monitor hydraulic oil temperature with Tool (G). Operate the machine until the oil temperature reaches 43 ± 5.6 °C (110 ± 10 °F).

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Illustration 11	g01411059

Move shift switch (15) to the HIGH SPEED position. Move parking brake switch (2) to the RELEASE position.

Modulate propulsion lever (1) forward until the peak pressure is registered at forward pressure tap (14) (approximately one-half of the total travel). Read pressure on Tool (A). The pressure should be 44000 ± 1000 kPa (6380 ± 145 psi).

Modulate propulsion lever (1) to the rear until the peak pressure is registered at reverse pressure tap (13) (approximately one-half of the total travel). Read pressure on Tool (A). The pressure should be 44000 ± 1000 kPa (6380 ± 145 psi).

Move propulsion lever (1) to the NEUTRAL position.

Move throttle switch (3) to the LOW IDLE position.

Move parking brake switch (2) to the ON position.

Move engine start switch (4) to the OFF position.

If either pressure reading is outside the specified range, go to Step 25. If both pressure readings are inside the specified range, go to Step 30.

Raise the cab. Refer to Disassembly and Assembly, KENR6413, "Cab - Tilt".

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Illustration 12	g01411063
The Drum Pump is Shown From Left Side.

Remove the cap from POR valve (16). Loosen the locknut and rotate adjustment screw clockwise in order to increase POR pressure. Rotate the adjustment screw counterclockwise in order to decrease POR pressure.