ARMY TM 9-6115-464-34
AIR FORCE TO 35C2-3-445-2
NAVY NAVFAC P-8-624-34
Section V. MAINTENANCE OF HYDRAULIC SYSTEM
(ELECTRO-HYDRAULIC GOVERNOR EQUIPPED PRECISE SETS ONLY)
3-39. GENERAL.
The hydraulic system provides a means of precise frequency control on all MEP-103A and some
MEP-113A precise generator sets. The system consists of a sump, a replaceable element type filter, a gear
type positive displacement pump and a hydraulic actuator unit. The hydraulic pump draws oil from the sump
and forces it through the filter. From the filter, the oil flows to the hydraulic actuator unit. An electrically
controlled set of valves alters the path of the oil which determines the positioning of the governor control
linkage. The position of the governor control linkage determines the fuel pump governor setting, which sets
engine speed. Changes in engine speed causes a corresponding increase or decrease in generator output
frequency.
3-40. HYDRAULIC SUMP.
a. Removal.
(1) Refer to the Operator and Unit Maintenance Manual and drain the hydraulic sump.
(2) Disconnect hydraulic lines (1, figure 3-33).
(3) Remove nuts (2), Iockwashers (3) and screws (4) to remove hydraulic sump (5).
(4) Remove cap and dipstick assembly (6) and elbows (7) from sump.
Cleaning, Inspection, and Repair
WARNING
Solvent, Dry Cleaning P–D-680, Type II is flammable and moderately toxic to skin,
eyes and respiratory tract. Eye and skin protection required. Good general ventilation
is normally adequate. Failure to observe this warning could cause servere personal
injury.
WARNING
Compressed air used for cleaning and drying purposes can create airborne particles
that may enter the eyes. Pressure shall not exceed 30 psig and use only with adequate
chip guards and chipping goggles. Failure to observe this warning could cause
servere personal injury.
(1) Clean all parts in solvent P-D-680 Type II and dry thoroughly with filtered compressed air.
(2) Flush interior of sump with an approved solvent and dry thoroughly.
(3) Visually inspect hydraulic sump for cracked or broken welds, defective paint, illegible markings, and
dents.
(4) Inspect cap and dipstick assembly for corrosion, bent dipstick, and other damage.
(5) Check all threads for crossing, stripping, and peening.
3-81
