Brake System

Page 31

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Volvo Bus Service and Maintenance Manual

 Wheel brake, inspection
56 Disassemble and check the wheel brake mechanism according to below. Lubricate before assembling.
 Manual slack adjusters
57 Check the slack adjuster travel.

Wheel brake, inspection and lubrication

Disassemble and clean the wheel brake mechanism and check the anchor bolts and brake rollers for wear. If worn, replace the bushings. Always replace the 0-rings. Check the brake linings and rub them if the surface is shiny.

Check the brake cam journalling for binding or abnormal looseness. Remedy if necessary.

Brake shoe assembly

Bus with anti-lock brakes, ABS:

Clean the thoothed gears and check their throw, which should be max. 0.3 mm. Make sure the sensors are recessed against the toothed gears and that the electric cables are not scuffed or incorrectly installed.

When assembling, lubricate all parts with graphite paste "Never Seize", P/N 1161035-9.

Check-tighten the slack adjuster anchor bolts and check for damage.

Apply the brake pedal and check brake pressure at the brake cylinders. Also check the function of the load-sensing valve.

Check for air leakage and remedy where necessary. Check the function of the parking brake and the blocking valve.

Slack adjusters

When checking the slack adjusters, chock the wheels and release the parking brake, if the bus is not jacked up. Let an assistant depress the brake pedal and hold it there.

Measure the distance "a" (see fig). Release the pedal and measure the distance "b". The difference between "a" and "b" is the travel measurement "c". If the travel is greater than that shown in the fig below, refer to Service Manual, Section 5, Brakes, for service procedures.

Note: The slack adjuster travel should be the same for both wheels on any one axle to ensure even brake application.

Slack adjusters

Slack adjuster travel

Min. brake pressure 600 kPa (6.0 kgf/cm2).

Manual slack adjuster travel: 25-30 mm.