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SERVICE MANUAL FOR SGR19 & SGR17
Troubles Presumable causes Countermeasures
Abnormal vibration is 1. Hydraulic system
observed. Trapped air Bleed system of air.
2. Chassis
Worn joints Replace with new ones.
Abnormal noises 1. Hydraulic system
(abnormal relief noise a. A specific hydraulic apparatus Consult with manufacturer of such
included) generates noises. apparatus.
b. Hydraulic pipes interfere Eliminate interference.
with each other.
2. Directly connected valve or other
related valves
a. Dust trapped in steering relief valve Disassemble, wash, re-assemble,
or overloadrelief valve, or reset pre-setpressure, or replace
abnormally worn valves defective valve assemblies with
new ones.
Oil leakage 1. Orbit-roll
– Worn or damaged oil seal of axle
(spool)
a. Contaminated fluid Replace fluid and filter element
with new.
b. High back pressure Lower back pressure lower than
specified level.
c. Rusted spool or sealing surfaces Replace orbit-roll with a new one.
– Damaged O-rings of contact surfaces
e. Bitten O-rings when orbit-roll is Replace damaged O-rings with
overhauled new ones.
f. Too low tightening torque of end cap Correct tightening torque.
screws
2. Directly connected valve or other
elated valves
a. Loosened bolts tightening valve Re-tighten bolts to specified torque.
directly to orbit-roll
b. Damaged O-rings Replace with new ones.
c. Damaged sealing surfaces and Replace damaged parts or assemblies.
grooves
Although various trouble causes are listed above, almost all troubles reported in the market are caused
by dust trapped in the system. Therefore take sufficient care to avoid dust when servicing the hydraulic
system.
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