MAINTENANCE OF FORKLIFTS - OD1660 - LESSON 1/TASK 1
(b) While the engine is running, open each bleeder valve
(located on top of the automatic slack adjuster) and depress the
brake pedal until the oil flows free of air. Close the bleed valves.
(c) The brakes should be applied and the pedal held down for at
least 10 seconds.
Repeat this three times, allowing at least 30
seconds between applications.
(d) Release the brakes and open all four bleeder valves. Bleed
the fluid from the brakes until the flow stops and then close the
Repeat the two steps above until no air can be
detected escaping from the fluid.
(e) Repeat the entire bleeding procedure if the brakes show any
evidence of dragging or overheating during the first few hours of
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
Hydraulic Brake Accumulator.
(1) General. The accumulator (figure 12 on the following page) is
the brake system to operate the brakes in an emergency even when the
engine is not running.
The accumulator is provided with a free
piston and is charged with dry nitrogen at approximately 275 psi.
This cylinder has a free riding piston.
Nitrogen is introduced
through a valve on the end of the cylinder to charge the cylinder.
After the cylinder has been charged, oil from the hydraulic system
enters the cylinder at the opposite end, forcing the nitrogen to
approximately 1300 psi. Access to the accumulator is accomplished by
removing the forward panels under the rear fenders.