ARMY TM 9-6115-464-12
AIR FORCE TO 35C2-3-445-1
NAVY NAVFAC P-8-624-12
Section Xl. UNIT MAINTENANCE OF THE HYDRAULIC SYSTEM
4-46 GENERAL. The hydraulic system is used only on MEP-103A and some MEP-113A Precise Generator Sets
equipped with electro-hydraulic governors. Its function is to provide a means of precise frequency control. The sys-
tem consists of a sump, a replaceable element type filter, a gear driven positive displacement type pump, a pressure
relief valve, a hydraulic actuator and interconnecting lines. The actuator hydraulically operates the governor control
linkage to change the governor setting. Changing the governor setting increases or decreases the engine speed
causing a corresponding increase or decrease in generator output frequency.
4-47 HYDRAULIC SUMP AND FILTER.
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
Disconnect return line from hydraulic actuator unit and allow the oil to drain into a suitable container
(Figure 4-28).
NOTE
Drain oil while it is at operating temperature to insure maximum suspension and
drainage of particles.
Remove lockwire and unscrew filter housing from filter head.
Withdraw filter element and discard.
Remove and discard packing and backup rings.
Clean filter housing with dry cleaning solvent (Federal Specification P-D-680) and dry with filtered com-
pressed air.
Soak replacement filter element in oil conforming to Military Specification MIL-H-5606.
Install replacement packing and back-up rings.
Insert oil soaked filter element into filter housing and fill housing with clean hydraulic oil.
Apply a thin coating of hydraulic oil to packing, back-up ring, and threads of filter head and housing.
Thread filter housing onto head hand tight and secure with lockwire.
Connect return line to hydraulic actuator unit and fill hydraulic sump as directed in paragraph 3-29.
NOTE
No maintenance is required on the pressure relief valve. If the valve is damaged
or fails to relieve pressure, replace the valve.
4-48 HYDRAULIC ACTUATOR UNIT FILTER.
a.
Disconnect hydraulic hose assembly (Figure 4-29).
b. Remove elbow, adapter, and filter.
c.
Clean filter with dry cleaning solvent (Federal Specification P-D-680) and dry thoroughly.
d. Inspect filter for holes, tears, and other damage. Replace filter if defects are noted.
e.
Install filter and elbow.
f.
Install hydraulic hose.
4-49
HYDRAULIC LINES.
NOTE
It is not necessary to remove all hydraulic lines to replace a single part. Only those
hydraulic lines requiring replacement need be removed.
a.
Removal. Drain hydraulic system (see paragraph 4-47). Remove damaged hydraulic lines by following
the ascending numerical sequence of index numbers (1 through 16) assigned to Figure 4-30.
b. Installation. Install hydraulic lines that are damaged by following the ascending numerical sequence of
index numbers (1 through 16) assigned to Figure 4-30.
4-71
