provide a contamination-free means of stowing the
discharge end of the service hose when the equipment
is not in actual use.
Model HSU-1 Fluid Service Unit
The Model HSU-1 fluid service unit (fig. 4-9) is
operated similarly to the H-250-1 unit, except that it
has a fluid-holding capacity of 3 gallons. Like the
H-250-1 servicing unit, the HSU-1 accepts a standard
1-gallon container and uses it as a fluid reservoir.
Additionally, it contains an integral 2-gallon reservoir
assembly. Three-micron filtration is incorporated to
ensure delivery of contamination-free fluid.
The integral 2-gallon reservoir assembly is made
of anodized cast aluminum and (along with a hand
pump assembly) is mounted to a cast aluminum base.
The lower can piercer is mounted on top of the
reservoir and allows fluid to flow from the installed
1-gallon container into the reservoir, automatically
replenishing it. A sight gauge indicates the fluid level
of the reservoir. It reads from 0 to 2 gallons, in
1/4-gallon increments. An indicated level of 2 gallons
or less means that the 1-gallon container is empty and
can be removed for replacement. A capped deaeration
port is located on top of the reservoir to permit
bleeding the air from the pump and output hose.
Can holder and handle assemblies are mounted
above the 2-gallon reservoir. The can holder positions
the installed 1-gallon fluid container directly above the
reservoir, and also provides a means of placing the
handle assembly over the container top. The handle
assembly is hinged to a bracket on the can holder
assembly. It is provided with a spring-loaded latch to
lock the handle in the closed position. In addition to
the carrying handle itself, the handle assembly
contains an upper can piercer, a vent check valve, and
a filter. A vent hose is connected between the top of
the reservoir (sight gauge) and the upper can piercer.
Fluid is delivered by a single-action, piston hand
pump that displaces 1.5 fluid ounces per full stroke at 0 to
250 psi. The pump is operated with a sliding pump
handle, which is held in the extended or retracted position
by a spring-loaded ball detent. A replaceable 3-micron
(absolute) disposable filter on the pump base removes
particulate contamination from the hydraulic fluid being
delivered to the suction side of the pump. The filter
unseats a shutoff valve, which closes the suction port
whenever the filter element is being replaced
The HSU-1 service unit is equipped with a 7-foot
service hose connected to the unit’s fluid output port at
the pump assembly. The hose assembly ends with a
short bent-tube assembly for direct connection to fill
fittings on the aircraft or components being serviced. A
3-micron, in-line filter is located between the hose end
and the tube. This prevents reverse-flow contamination
and serves as a final filter. When the fluid service unit is
not in use, it is stored by wrapping the hose assembly
around the can holder assembly and fastening the tube
end to the hose storage fitting on the base.
Model 310 Fluid Service Cart
The Model 310 fluid service cart (fig. 4-10) is a
hand-propelled, mobile unit designed to service
4-25
Figure 4-10.—Model 310 fluid service cart.
