MAINTENANCE OF FORKLIFTS - OD1660 - LESSON 1/TASK 1
tube. The brake system receives its oil supply (OE/HDO-10), from the
forklift's main hydraulic oil supply tank.
Pressure is supplied by an engine-driven hydraulic pump and
application is controlled by an applicator valve located under the
operator's floor plate. An accumulator is incorporated in the brake
Brake adjustment is accomplished by slack
adjusters located in the hydraulic lines between the applicator valve
and the wheel brake assemblies. The components of the brake assembly
consist of a cast torque plate, upon which the expander tube is
mounted, and an inlet connection into which the expander tube is
Steel side frames with welded steel torque bars are
attached to both sides of the torque plate. Brake linings mounted on
steel shoes are inserted between the torque bars and side frames and
are held in position by retracting springs.
Steel shields are used
to bridge the gap between the shoes and protect the expander tube.
The spring inserted under the center of the linings and over the
steel brakeshoes withdraw the block and shoe assemblies from the
surface of the brakedrum after the actuation pressure has been
Maintenance. If a malfunction occurs which cannot be corrected
by the bleeding process, the operator should report this to
intermediate direct support (IDS) maintenance.
Lining wear can be
detected by observing the arc of the brake lining retract springs.
Retract springs are visible on the inboard side of the brake
assembly, just below the outer circumference of the backing plate.
Flattened springs (with the brakes off) indicate a need for lining
replacement. When the lining is in good condition, the springs will
form a shallow arc. The brake fluid should be checked for air after
the first shift of operation.
If the brakes do not release properly after application, replace the
hydraulic tank filter.
A clogged or restricted filter will prevent
the oil from returning to the tank and, therefore, will not allow the
brakes to release.