Komatsu 830E Shop Manual page 390

FIGURE 6-11. GRIP FORCE SLIPPAGE CHECK
3. If slippage occurs between the specified force
limits, move grips to position on pin (shown in
Figure 6-13) and install in piston assembly.
4. If slippage occurs below the 400 lb. (1779 N)
limit, either grips or grips and return pin assembly
must be replaced. Use sleeve (A) (Figure 6-6)
and arbor press to slip both grips off return pin.
Inspect return pin for nicks and wear. Slight nicks
that can be polished out by hand can be reused, if
subsequent slip inspection is acceptable. Any
rework of return pin should be avoided unless
absolutely necessary. Burred threads can be
repaired by use of a 3/8-24 UNF 3 thread die.
Bent, battered or badly worn return pins must be
replaced.
J6-10
Grip assemblies and return pins are critical items
in the operation of the piston return mechanism
and should not be mishandled. Under no circum-
stances should pin diameter be clamped in a vise
or gripped with pliers. In normal use, surface of pin
will show only a very slow rate of wear and both
pins and grips will normally last through many
brake lining changes and brake overhauls.
Spring Force Measurement
FIGURE 6-12. MEASURING SPRING FORCE
Rockwell Armature Speed Rear Disc Brakes
5. Install grips on return pin, as illustrated in Figure
6-13. Position grip and pilot pin assembly as
shown to transfer grip assembly from pilot pin to
piston return pin. Second grip should be seated
firmly against first, after which slip force should be
checked as previously described. After correct
slippage is verified, position of grips on pin should
remain as shown in Figure 6-13, for piston
assembly.
1. Inspect return spring for a free height dimension
of 1.888 in. (30 mm). A measured height of less
than 1.125 in. (28.5 mm) is an indication that
brake assembly has been subjected to high tem-
perature operation, resulting in permanent set of
spring. This will result in loss of spring force at
working height.
J06020