Q14-26. What substance should all internal parts of
SINGLE AND DUAL DISC BRAKES
the power brake valve be immersed in before
Automatically adjusted single and dual disc brakes
reassembly?
are designed to provide a satisfactory running
Q14-27. How much hydraulic test stand pressure is
clearance between the brake disc and the brake linings.
required to perform an operational test on a
The self-adjusting feature of the brake maintains the
power brake valve?
desired lining and puck-to-disc clearance, regardless
Q14-28. What fluid should be applied to all sealing
of lining or puck wear. See figure 14-26. When you
devices during reassembly of the master brake
apply the brakes, hydraulic pressure moves each piston
cylinder?
and its pucks or linings against the disc or discs as
applicable. As the linings wear, the piston pushes
Q14-29. What device should be installed on the end of a
against the adjusting pin (through the spring guide) and
piston rod before disassembling a master
moves the pin against the friction of the adjusting pin
brake cylinder to prevent personal injury due
grip. When you release the brake pressure, the force of
to preload of the springs?
the return spring moves the piston away from the brake
Q14-30. What letters are used after the applicable step
disc, but it does not move the adjusting pin, which is
to identify steps that require quality assurance
held by the friction of the pin grip. The piston moves
verification in the Maintenance Instruction
away from the disc until it stops against the head of the
Manual (MIM)?
adjusting pin. Thus, regardless of the amount of wear,
the same travel of the piston will be required to apply
BRAKE ASSEMBLY MAINTENANCE
the brake, and the running clearance will be
maintained.
LEARNING OBJECTIVE: Identify the
The automatic adjusting feature may be referred to
maintenance procedures for the single disc,
as a captured torquing type or captured nontorquing
the dual disc, and the trimetallic disc brake
t y p e . F i g u r e 1 4 - 2 7 s h ow s a t y p i c a l c a p t u r e d
assemblies.
torquing-type automatic adjuster. It is mandatory that
clearance be established between the linings and the
The description and operation of the single disc,
discs before torquing the automatic adjusting nut to the
dual disc, multiple disc, and segmented rotor brake
amount specified for the brake involved. Otherwise,
a s s e m b l i e s w e r e c ove r e d e a r l i e r. A d d i t i o n a l
the brake will drag until an amount equal to the built-in
maintenance information on the single and dual disc
clearance is worn from the face of the linings. With the
brake assemblies and a description and operation of the
adjusting nuts properly torqued, the friction between
trimetallic disc brake assemblies are covered here.
Figure 14-26.--Brake self-adjustment feature--single disc brake.
14-27
