| |
Back
Air-Over-Hydraulic | Up
Construction Mechanic Advanced - Construction methods and practices | Next
Figure 6-14.—Automotive type emergency/parking brake axle mounted. |
hydraulic pressure gauges. All gauges should register
zero without lagging. When pressure is noted at the air
pressure gauge, a sticking relay piston, damaged or
corroded control valve poppet, or a ruptured control
valve diaphragm exists. Pressure at the hydraulic
pressure gauges indicates a sticking hydraulic piston, a
sticking power piston, or a weak or broken piston return
spring. If the hydraulic pressure gauges show a slow
pressure drop, it indicates a defective check valve (in the
hydraulic piston) or a defective residual line check
valve.
If the tests indicate external air leakage, tighten the
control line connections, and or replace a damaged
control line, control line gasket, or double check the
valve. For internal air leakage you must remove the unit
to replace worn or damaged power piston packing or end
plate gasket, and repair or replace the cylinder body or
end plate.
If the tests indicate hydraulic fluid leakage, an
inoperative control valve, sticking power piston, relay
piston, or hydraulic piston, remove the unit for
disassembly and repair or replace the worn or damaged
parts.
PARKING/EMERGENCY BRAKES
Serviceable parking/emergency brakes are essential
to the safe operation of any piece of automotive or
construction equipment. Several types of these brakes
are manufactured, such as the external contraction,
drum, and disk types (fig. 6-13). These are drive line
brakes common to heavy construction equipment. These
Figure 6-13.—Examples of drive line emergency/parking brakes, transmission mounted.
6-17
|
