120M and 12M Motor Graders Braking and Hydraulic Fan System Caterpillar

Brake Accumulator Charging Valve - Check

Usage:

120M B9C

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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.

Specification

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Table 1
Brake Accumulator Charging Valve - Test
Date	Equipment ID Code
Operation	Spec	Result of First Check	Result of the Second Check
Cut-in Pressure	10400 ± 350 kPa (1508 ± 50 psi)
Cut-out Pressure	17200 ± 1700 kPa (2495 ± 246 psi)

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Table 2
Brake Accumulator Charging Valve
Number of pumps of the service brake pedal until the warning signal activates ⁽¹⁾	Pass/Fail

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^( 1 )

A minimum of nine pumps are required for the system to pass the test.

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Table 3
Cut-out to Cut-in Purge Pressure Specification
Specified Time Measured in Minutes	Actual Time Measured in Minutes
5 minutes or greater

Introduction

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Illustration 1	g03554677
Front view of the manifold

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Illustration 2	g03554679
Rear view of the manifold

This test will verify that the software, hydraulics, and sensors are performing properly.

Required Tooling

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Table 4
Required Tools
Tool	Part Number	Description	Qty
F		Caterpillar Electronic Technician (ET)	1

Preparation for Test

Warm the hydraulic oil up to 65° ± 5°C (149° ± 9°F).

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 all work tools to the ground. Stop the engine and put chocks in front of the wheels and behind the wheels.

Hook up Cat Electronic Technician (ET) (7) to the machine

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Illustration 3	g03615095

When the first screen in ET opens, click the connect icon.

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Illustration 4	g03614407

ET is connecting to the machines ECM

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Illustration 5	g03614408

Select the Trans/Chassis ECM

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Illustration 6	g03614409

Select the "status" icon.

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Illustration 7	g03614561

5. Select "Brake Accumulator Charging" status listed under Trans/Chassis ECM.

Start the engine and apply the parking brake. Pump the brakes down to allow the brake system to charge and reach cutout pressure.

Perform the Test

Pump the service brake pedal at an interval of one second on and one second off while the engine is running. Pump the brakes until the cut in pressure is reached. The cut in pressure on the gauge should be 10400 ± 350 kPa (1508 ± 50 psi). Record the pressure.
The minimum pressure on the gauge is the cut in pressure.

The system will charge and the cutout pressure will then be reached. Record the cutout pressure reading. The cutout pressure should be 17200 ± 1700 kPa (2495 ± 246 psi).
The greater pressure is the cut out pressure.

Allow the brake system to reach cutout pressure and repeat Step 2, and Step 3 and record the pressure.
The two charge cycles are to verify that the software, hydraulics and sensors are performing properly.

Pump the service brake pedal until the cut-in pressure is reached. Allow the brake charging valve to charge the accumulators. When the accumulators have reached cut-out pressure, do not input any commands to the machine (do not steer, depress the brake pedal, move out of park, etc.). The accumulator pressure will naturally purge down over time, until the accumulators reach cut-in pressure. The time taken to reach cut-in pressure should be 5 minutes or greater.

Pump the brakes until the system reaches cut in pressure. Then allow the brakes to charge until the cut out pressure is reached. Immediately shut off the engine when the cut out pressure is reached.

Turn the key back on without starting the engine this process will power up the display.

Pump the service brakes at a rate of one second on and one second off. Record the number of pumps required to lower the pressure until the low-pressure warning indicator is illuminated. Then continue pumping the brakes until the parking brake indicator begins flashing.

Verify that the low-pressure warning indicator (2) illuminates at a higher pressure or prior to the parking brake indicator (3) .

The minimum number of brake applications from the charge valve cutout to the illuminating the brake indicator is 12. Record whether the system passes or fails.