BENDIX DD-3 Manuale - Pagina 3
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Stampa la paginaRELEASING (SD-3
ACTUATOR)
™
To release the park application, air pressure in excess of 40
psi must be applied at the lock port and a service application
slightly greater than the locked-in application made. For
practical purposes, a full reservoir application should be made
and held for 5 seconds to produce sufficient forward motion
of the shaft to allow disengagement of the lock mechanism.
Various control systems are used to achieve the proper
sequence of control signals. Bendix brochure "Off Highway
Vehicle Braking System" (BW 1283) explains one such
system.
PREVENTIVE MAINTENANCE
GENERAL
Depending on experience and type of operation, the drain
slot in the actuator non-pressure plate should be checked
and cleaned of any restricting road grime, mud, ice, snow,
etc. Check or replace actuator boot if loose on the push
rod or if worn.
Brake should be adjusted at the slack adjuster as is
customary with standard brake chambers. Push rod travel
should be as short as possible without brakes dragging.
Excessive travel not only shortens the normal service life of
the diaphragm but gives slow braking response and wastes
air.
Push rod to slack adjuster alignment should be checked in
both the applied and released positions. The rod should
move out and return promptly without binding.
Check the angle formed by the slack adjuster arm and
push rod. It should be 90° or greater when the actuator is
in the applied or released position when brakes are properly
adjusted.
EVERY MONTH, 300 OPERATING HOURS, OR AFTER
8000 MILES
Check push rod travel, alignment and nuts for tightness.
Check hoses. (See slack adjuster for adjustment.)
Check for proper operation.
EVERY 3 MONTHS, 900 OPERATING HOURS, OR 25,000
MILES
When grease fitting is provided, grease with Lubriplate
"Aero" lubricant.
EVERY 12 MONTHS, 3600 OPERATING HOURS, OR
100,000 MILES
Disassemble, inspect diaphragms and rubber parts, rod,
springs, and non-pressure plate. Replace all parts worn or
damaged. Check for proper operation before placing vehicle
in service.
REMOVING AND INSTALLING
Block and hold the vehicle by some means other than air
brakes.
REMOVING DD-3
ACTUATOR
™
With the actuators in a released position, disconnect the
air lines to the service and auxiliary ports. Move the park
control valve to the park position which will exhaust the air
from the lock port. Disconnect the lock port line. Remove
yoke pin and back off slack adjuster. Remove mounting
nuts, then actuator.
REMOVING SD-3
™
ACTUATOR
If the SD-3
™
actuator is mounted on a vehicle with its own
air supply, the parking control should be placed in the release
position with the air system completely charged. Disconnect
the service port line. Move the park control valve to the park
position and disconnect the lock line. Remove the actuator
as above.
If the SD-3
actuator is mounted on a trailer, with no air
™
supply present and in the applied position, completely drain
trailer reservoir. Remove delivery and lock port lines from
actuator. Release force from actuator by backing off slack
adjuster or mounting nuts or both. Remove actuator.
INSTALLING
IMPORTANT - DD-3
and SD-3
™
installed with the exhaust check valve down and the drain
slot pointing down.
Mount actuator to mounting bracket and tighten securely.
Fasten actuator push rod yoke to slack adjuster with yoke
pin. Lock yoke pin with cotter pin. The angle formed by the
push rod and slack adjuster arm should be greater than
90°.
Connect air lines to actuator. Take care that the correct line
is installed in the correct port.
Adjust brakes.
DISASSEMBLY
1. Clean actuator exterior of all road grime and mark in
such a way so it can be assembled in the same manner.
2. Remove yoke and yoke lock nuts.
3. Remove splash guard, boot, felt breather, and gasket.
4. Remove auxiliary and service clamping ring nuts and
bolts.
safety actuators must be
™
3