12M, 140, 140M and 160M Motor Graders Braking and Hydraulic Fan System Brake System Air

Brake System Air - Purge

12M, 140, 140M and 160M Motor Graders Braking and Hydraulic Fan System [RENR8471]

BRAKING SYSTEM

12M, 140, 140M and 160M Motor Graders Braking and Hydraulic Fan System Brake System Air - Purge

1.1. Specifications

2.1. Introduction

3.1. Required Tools

4.1. Machine Preparation

5.1. Procedure to Purge the Air From the Brake System

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Personal injury or death can result if two persons are not used in the following procedure.

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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 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.

Specifications

There are no specifications for this procedure.

This procedure will remove air from the brake system.

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Table 1
Required Tool
Item	Description	Qty
F	Transparent tube 6.4 mm (0.25 inch) in diameter	4
	Suitable containers	4

Prepare the machine for testing by completing the procedure that is specified in the Service Manual module Troubleshooting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.
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 place chocks in front of the wheels and behind the wheels.

Check the hydraulic tank oil level. Make sure that you maintain the correct oil level in the hydraulic oil tank throughout the air removal procedure.

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Illustration 1	g01292758
(1) Air purge screw. The guard has been removed for clarity. The four air purge screws (1) for the service brakes are located on the top of the corresponding wheel group.

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Illustration 2	g02150060
(1) Air purge screw with the drain hose (F) attached. The air purge screw is not in sight.

Fasten one end of a transparent tube (F) to each air purge screw. Place the other end of the tube into a suitable container for collecting the hydraulic oil.

Hold the end of the tubing (F) in suitable containers and open all four purge screws.
Start the engine. Allow the oil pressure to increase to the cutout pressure. Stop the engine.
The operator should slowly depress the brake pedal until the accumulators are fully discharged.
Release the pedal.
Fill the hydraulic oil tank if necessary.
While the purge screws still open Repeat Step 2 through Step 5 at least four times. Repeat Step 2 through Step 5 until no air bubbles are visible.
While the air purge screws still open, start the engine and depress the pedal slightly until the oil is flowing from the tubes. Allow oil to flow from the tubes for a minimum of one minute. Allow oil to flow from the tubes until no air bubbles are visible. Make sure that the hydraulic tank oil level is maintained during this procedure.
Stop the engine.
Tighten all of the air purge screws. Remove tubes (F).