Gradall LOED 534A, Service Manual

Page: 32 / 91

SECTION V EMERGENCY PLUNGER AND HOUSING REPAIR
To manufacture a high quality control valve having a minimum amount of leakage, each plunger is honed to
fit its respective bore. It is, therefore, recommended that the valve returned to the factory to repair
or replacement.
S h o u l d a s i t u a t i o n r e q u i r e r e b u i l d i n g t h e v a l v e , w e r e c o m m e n d t h e f o l l o w i n g p r o c e d u r e s :
Remove valve from the equipment and thoroughly clean all external surfaces.
Disassemble valve, tagging plungers to assure reassembly to the same bore. Do not damage plunger
seals during disassembly.
Clean all internal parts with solvent and blow dry with compressed air.
Plate plunger .001 to .002 with crack-free chrome plate.
Refinish plated plunger to within .0002 of being straight and round with a surface finish of 12 RMS
or greater.
Hone valve bore until plunger fits bore smoothly. Permissible clearance between bore and plunger is
.0002 to .0005.
Thoroughly flush valve housing, grease detents and other sliding parts and reassemble valve. During
assembly do not damage plunger seals.
If a new plunger is required, refit new plunger to the respective bore using the same procedures as for a
rebuilt plunger.
NOTE: HUSCO IS NOT ABLE TO PERFORM FACTORY REPAIR SERVICE WITHOUT WRITTEN AUTHORIZATION
FROM THE ORIGINAL EQUIPMENT MANUFACTURER.
Returned valves will be held at HUSCO until authorization is obtained. All billing will be mailed to the
original manufacturer. The manufacturer will, bill the owner of the equipment.
Valves will be shipped directly to the owner of the equipment unless otherwise instructured.
Plunger leakage allowance is tabulated in cubic inches per minute for a five minute average. Oil temperature
of 80 F. with a viscosity of 145 to 155 S.U.S. of 100 f., and viscosity index of 95. Pressure constant
at 1000 p.s.i.
If leakage exceeds maximum, the valve should be returned for factory rebuilding or replacement *
NOTE: ALL DYNAMIC SEALS ARE MADE OF SPECIAL COMPOUNDS AND SHOULD BE PURCHASED FROM
HUSCO OR AN APPROVED SOURCE.
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FIGURE 27