140 GC Motor Grader Systems Caterpillar

Brake Control Valve (Service) - Check

Usage:

140 GC W92

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Personal injury can result if the machine moves while testing.

If the machine begins to move during test, reduce the engine speed immediately and engage the parking brake.

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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine.

To prevent possible injury, perform the procedure that follows before testing and adjusting the brake system.

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Table 1
Maximum Amount That The Service Brake Pressure Can Drop After 2 Minutes
138 kPa (20 psi)

Reference: Before you begin this procedure, refer to the Operation and Maintenance Manual, "Prepare the Machine for Maintenance".

The brake control valve (service) controls the flow of pressurized oil.

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Illustration 1	g06221007
Tooling (T1) 198-4240 Digital Pressure Indicator Gp

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Table 2
Required Tools
Item		Qty	Part Number	Part Name
T1		1	198-4240	Digital Pressure Indicator Gp
	T1a	1	198-4234	Digital Indicator
	T1b	2	198-4239	Pressure Sensor Gp (0 to 41,369 kPa (0 to 6,000 psi))
	T1c	2	198-4236	Adapter Cable As
T2		2	6V-3965	Fitting (TEST)
T3		2	153-4906	O-Ring Seal

Move the machine to a smooth, horizontal location. Move the machine away from other operating machines and away from personnel. Place the transmission direction control switch in the NEUTRAL position. Engage the parking brake. Lower the work tools to the ground. Stop the engine and put chocks in front of the wheels and behind the wheels.
Remove the pressure from the brake system by pumping the service brake pedal at a rate of one second ON and one second OFF. Continue to pump the brakes until a minimum of 110 applications have been completed. Do not assume that the pressure is removed from the circuit if the brake pedal has no resistance.
Assemble each (T2) to each (T3).
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Illustration 2 g03581036

Left side service brake
Remove the plug from the test port (1) for the left service brakes. Install fitting (T2) and Tooling (T1) onto the test port (1).
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Illustration 3 g03581037

Right side service brake
Remove the plug from the test port (2) for the right service brakes. Install fitting (T2) and Tooling (T1) onto the test port (2).
Look at the pressure gauges. Before you start the engine, the hydraulic oil pressure should be 0 kPa (0 psi).

Start the engine. Allow the hydraulic oil to reach normal operating temperature. Normal operating is 60° ± 5°C (140° ± 9°F).
Run the engine at LOW IDLE
Depress the brake pedal. Do not permit the brake pedal to come up. Shut off the engine. Record the left side and right side pressure readings after 2 minutes.
The left-hand and right-hand service brake pressure shall not decrease more than 138 kPa (20 psi) in 2 minutes.
If the service brake pressure drops more than 138 kPa (20 psi) after 2 minutes, the brake control valve must be inspected for the cause of leakage.
Remove the pressure from the brake system by pumping the service brake pedal at a rate of one second ON and one second OFF. Continue to pump the brakes until a minimum of 110 applications have been completed. Do not assume that the pressure is removed from the circuit if the brake pedal has no resistance. Remove all test equipment and reinstall the plugs.