c. Safety Relief Valve (No. 2). The safety relief
valve is self-contained and is also located in the
The hose connects at the discharge port of the
submerged end of the pump. This safety relief valve
pump assembly and inlet port of the cylinder and ram
provides an additional safety feature, its function is to
assembly. The flexible hose is provided to transfer
bypass hydraulic fluid to the reservoir when excessive
hydraulic fluid, under pressure (2235 psi), during raising
pressure is encountered inside the cylinder and ram
operations and to return hydraulic fluid during lowering
A sudden load increase or thermal
expansion of the hydraulic fluid will cause the safety
relief valve to open.
1-9. Foot Assemblies.
d. Intake and Discharge Valves. The intake and
discharge valves consist of two balls and two springs
Each foot assembly consists of a caster, caster
assembled in tandem in the pump passage between the
mount, and caster arm assembly. The three foot
intake port and pump cylinder. The intake valve is the
assemblies mount on the leg, or leg extension, of the
first valve in the pump passage and permits hydraulic
tripod assembly for ease of movement and to prevent
fluid to be drawn from the reservoir into the pump
the hydraulic jack from shifting.
cylinder. The discharge valve is the second valve in the
pump passage and permits hydraulic fluid, under
1-10. Tripod Assembly,
pressure (2235 psi), to pass from the pump cylinder to
the cylinder and ram assembly.
The tripod assembly is the mounting base for the
cylinder and ram assembly.
The tripod assembly
consists of three tubular legs, four sets of three leg
Components. The release assembly and associated
extensions, five sets of six braces, six brace links, and
components are located near the pump mounting flange
one tension bar. By adding or removing leg extension,
at the right-hand side of the pump handle socket. The
the hydraulic jack may be assembled to any one of five
release assembly controls the raising and lowering of
basic closed heights configurations.
the cylinder and ram assembly ram.
1-7. Cylinder and Ram Assembly.
The identification nameplate is located between
The cylinder and ram assembly consists basically
two attachment lugs at the top of the cylinder and ram
of an outer cylinder and inner ram with extension screw.
assembly. The assembly decal is centered on the
The cylinder mounts on the tripod assembly to form the
cylinder of the cylinder and ram assembly. A capacity
upper part of the hydraulic jack. The ram contains one
decal is located on the side of the pump assembly. '-'he
longitudinal and one spiral groove extending from the
instruction decal is located on the top of the pump
top of the ram to the top of the upper bearing ring. The
assembly near the air vent.
ram is guided during raising and lowering operations by
(See figure 1-2,)
a key in the ram upper bearing. A ram lock nut
assembly rotates downward on the spiral groove of the
1-12. Leading Particulars.
ram as the ram is being raised. The ram lock nut
assembly is provided to afford protection to personnel
Refer to table 1-1 for leading particulars.
and equipment in event of hydraulic failure or slipping of
load. An 18-inch extension screw is housed inside the
1-13. Differences in Models.
ram and may be manually raised to take up clearance
between closed height of the hydraulic jack and
This manual covers only the hydraulic jack, part
number 50J25178 (type B6). No known differences
exist for the design covered by this manual.
Do not extend extension screw
1-14. Painting Requirements.
more than 18 inches.
Paint tripod assembly in accordance with TM 55-
1500-204-25 / I.