BENDIX M-21-M-22 ANTILOCK MOD ASSY Manual de servicio descargar pdf (Pagina 13)

Slack Adjusters (automatic)

The slack adjuster is the link between the brake chamber and the foundation brake

camshaft. It transforms and multiplies the force developed by the chamber into

torque, which applies the brakes via the brake camshaft. The automatic adjustment

provided by the slack adjuster results in consistent brake-lining-to-drum clearance and

brake actuator stroke.

The key to its operation is the ability to complete the brake adjustment during the

early part of each brake application, and to cease adjusting as resistance to brake

cam rotation begins to build. This aspect of the adjustment mechanism’s operation

prevents over-adjustment due to: lining compression, actuator bracket deflection,

drum and foundation brake component distortion, or brake components wear.

Air control valves

Both the tractor parking brake (PP1) and the trailer air supply (PP7) valves are pres-

sure-sensitive push-pull type control valves, which automatically return to the exhaust

(button out) position when supply pressure is below the required minimum. The valves

may be manually operated to either position when the pressure is above the required

minimum.

The control valve knob for the tractor parking brake is diamond-shaped and yellow in

color. The trailer air supply knob is hexagonal-shaped and red in color.

HOW THEY WORK

Ottawa tractors are equipped with spring brakes for parking. The parking system is

operated manually by a cab-mounted parking brake control valve. See figure 1. The

purpose of the parking (spring) brakes is to hold the vehicle while in the parked posi-

tion. The parking (spring) brakes also assist in stopping the vehicle, should the service

brakes fail.

The Ottawa tractor is equipped with modular Trailer Air Supply and Parking Brake con-

trol valves. These two controls operate together to control the parking brakes on the

tractor and trailer combination.

After the tractor is properly coupled to the trailer and both Service (BLUE) and Supply

(RED) air lines have been connected, the combination trailer brakes function as follows:

To charge the trailer air supply and release the trailer parking/spring brakes BOTH the

Trailer Air Supply and Parking Brake controls must be pushed in TOGETHER (RED and

YELLOW). The foot-operated brake treadle must be fully applied while the trailer air

supply is being charged, to prevent the combination from rolling after the trailer

parking brakes release.

To release the tractor spring brakes the (YELLOW) Parking Brake control must be

pushed in (trailer spring brakes released). Pressing the Parking Brake Control will

release the tractor spring brakes and the tractor and trailer will roll freely, with both con-

trols pushed in (spring brakes released): the combination is in the normal driving mode.

Air Brake System

Revised 11/15/99

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BENDIX M-21-M-22 ANTILOCK MOD ASSY Manual de servicio Pagina 13