SECTION 9
HYDRAULIC SYSTEM
Dec 2002
p. 9-4
05130471
9.2.3 Motor Startup
The electric motor (1) starts in two stages (Wye-Delta). During the initial
(Wye) stage, piston pump (2) pressure is maintained low to reduce torque
load on the motor. Piston pump depressurization is accomplished by
delayed closing of check valve (9) located in the manifold (25). After
several seconds, flow through orifice (10) builds pressure behind the
check valve (9), closing it and directing pump flow into the main working
circuit. By the time this hydraulic shift occurs, the motor will have
shifted to full speed (Delta), capable of full torque.
9.3 Motor/Hydraulic Service Maintenance
9.3.1 Pump Compensator Adjustment
Pressure for HP water is raised or lowered by adjusting the compensator
screw (34) on the piston pump. Note that there are 2 adjustment screws,
inner and outer, on the same compensator assembly. The inner
adjustment screw (34) can be adjusted to pressures up to 207 bar (3,000
psi) and is used for making all pump adjustments. The outer adjustment
screw (35) pre-set at the factory and should not require re- adjustment.
NOTE:
The outer pressure adjustment screw (35) is set in the range of 10-22 bar
(145-320 psi). Standard setting is 20 bar (290 psi).
Use a 3mm hex Allen wrench (31) to turn the compensator adjustment
screw (34). Adjust pressure while the HP water is blocked and the pump
is producing little or no flow. Loosen the jam nut (33). Rotate the screw
clockwise to increase pressure. Replace the cap nut (32) over the
adjustment screw after changing the pressure setting, otherwise
hydraulic oil will leak from the compensator.
NOTE:
Do not adjust the compensator pressure control to pressures greater than 207
bar (3,000 psi). Doing so will cause the main relief to open, limiting hydraulic
pressure to 234 bar (3,400 psi). Also due to repeated opening of the main relief
valve the hydraulic oil may heat excessively.
The hydraulic oil filter should be checked daily and replaced when
excessive pressure drop is indicated during normal operating conditions.
Replace filter element when the pressure reading is 1.4 bar (20 psi) above
normal when at operating temperature. Maximum normal pressure is
1.7 bar (25 psi). The hydraulic oil should be replaced every 2000 hours
or yearly, whichever occurs first. For hydraulic oil and filter
maintenance, see Section 10, Recirculation System.
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