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 TM 55-1905-217-12
SECTION XIX. HYDRAULIC RAMP HOIST
4-85. General
4-86. Filling Ramp Hoist Hydraulic System with Fluid
a. The ramp hoisting arrangement consists of a hoisting
a. .Recommended
oils are 2135 TH.,
MIL
cable deadended to one side of the craft, running through
,17672B; and 207.5 TH., MIl17672B.
fairlead sheaves through the ramp and to a winch on the
b. The 76-gallon ramp hoist hydraulic system tank
opposite side. The systems for hull numbers 8500 thru
is located in the engine room. FU the hydraulic system
8619 and hull numbers 8620 thru 8560 and 8580 thru
through the tank filler. Open gate valve at bottom of tank
8618 are similar in operation but most components differ.
(hull numbers 8500 thru 8519). Fill tank until oil appears
The winch on hull numbers 8500 thru 8519 is on the ,port
at tank sight gage. Place control valve in neutral. Fill lines
side and on hull numbers 8520 thru 8560 and '8580 thru
and pumps by loosening pump discharge hoses at union
8618 the winch is on the starboard side.
b. Winches are powered by hydraulic motors.
swivel. Tighten hoses when oil appears.
Other system components include a four way control
c. Turn pumps over slowly, with engines idling,
valve, counterbalance valve, two engine driven pumps,
to draw oil into pumps. Oil level will drop as system fills.
two check valves, suction line strainers, and return line
Continue adding oil to tank throughout filling operation.
filters. See figure 1-12 for the hull numbers 8500 thru
Continue purging air from system.
8519 ramp system diagram, or figure 1-13 for the hull
numbers 8520 thru 8539 ramp system diagram, or figure
CAUTION
8618 ramp system diagram. Hull numbers 8540 thru
Air in system will cause spongy, erratic
8560 and 8580 thru 8618 incorporate a closed hydraulic
operation of winch or rapid fluctuation of oil
system. Return hydraulic fluid from the counterbalance
level.
valve is routed to the reservoir.
d. If air persists in system, check suction lines for
c. Emergency lowering of the ramp is accomplished
leak.
by a manual brake release on hull numbers 8500 thru
e. Run one pump approximately 15 minutes.
8'519 and by a hand operated hydraulic pump brake
Shut down pump.
release on hull numbers 8520 thru 8560 and 8580 thru
8618. Two chain hoists are stored in the l1azarette to be
f. Remove and inspect filter and strainer; clean
used for emergency lifting of the ramp. See figure 2-9.
strainer clement in either cleaning solvent Federal
Specification P-4D-80, type I, or kerosene, and replace
d. On hull numbers 8540 thru 8560 and 8580 thru
filter element if it is dirty. Repeat steps e and f until
8618, a hydraulically actuated mechanical latch is
strainers and filters remain clean.
provided to secure the ramp in an up position. The latch
is unlocked by hydraulic pressure applied by placing the
CAUTION
ramp hoist lever (fig. 2-3) in the RAMP-DOWN position.
if metal particles or other foreign matter are
The latch is automatically locked when the ramp is
found in filter or strainer, investigate to
raised. The latch can be unlocked during emergency
determine source.
conditions (no pressure in ramp hydraulic system
engines not operating, etc.) by ,applying hydraulic
g. On hull numbers i840 thru 8560 and 8680 thru
pressure with the winch brake release hand pump,
8618, the ramp system is purged of air as described
located on the starboard side of the forward cargo hull. A
above. Additionally, it is necessary to remove air from the
selector valve, located on the starboard side of the
ramp latch system. This is done as follows:
forward cargo hull, selects the source of hydraulic
(1) With the ramp hoist cable disconnected from the
pressure for unlocking the ramp latch. In the NORMAL
winch and one engine driven pump running, place the
position, pressure from the engine driven pumps is
ramp hoist control valve lever in the RAMP-DOWN
applied to the latch. When in the EMERGENCY position,
Edition.
the hydraulic pressure originates at the hydraulic ramp
system hand pump.
(2) Loosen connection at selector valve from
engine driven pump, retighten when fluid is free of -
bubbles.
4-74
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