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|  MIL-T-52843C
permanent deformation and without exceeding the fluid temperature
limit of 250 F with an initial fluid temperature of not less than
157 F in an ambient temperature of not lower than 25 F.
3.11.1.2 Hydrostatic transmission. The hydrostatic transmission
shall be a closed loop type with a reversible variable displacement
pump and a reversible variable or reversible fixed displacement
motor. A charge pump shall be provided and shall be gear or shaft
driven by the engine and shall provide sufficient oil under pressure
to retard cavitation of the pump and motor and to maintain a
constant, smooth control lever response independent of operating
conditions performed at full throttle engine speeds. With an oil
temperature of 140 5 F and new filter, the vacuum at the charge
pump inlet port shall not exceed 5 inches Hg when tested in
accordance with 4.6.2.21.1. A shuttle valve or equivalent means shall
be provided to automatically prevent loss of high pressure oil from
the closed loop pump/motor circuit during the transition of rapid
change in direction of the forklift. A set of reduction gears with a
minimum of two speed ranges capable of being shifted on the move
under full engine torque may be used in conjunction with the
hydrostatic transmission. When a gear range selector is provided it
shall be accessible to the operator in the normal operating position
and shall be labeled to indicate speed ranges. Oil temperatures in
the transmission shall not exceed 180 F when measured at the pump
case drain and motor case drain under any operating conditions
specified herein. When a heat exchanger is required to meet
temperature limits stated herein, means shall be provided to insure
recommended case pressures of the pump and motor are not exceeded
during all operating conditions specified herein including cold
weather start-up. The transmission shall be capable of withstanding
maximum stall operation for a minimum of 30 seconds without damage or
permanent deformation and without exceeding the fluid temperature
limit of 180 F. The system shall withstand all operations specified
herein without permanent deformation, damage, or leakage.
3.11.2 Rear axle oscillation. The rear axle shall oscillate freely
such that the total vertical travel of each rear wheel shall be a
minimum of 14 inches (seven inches above and seven inches below the
horizontal axle centerline.)
3.12 Hydraulic system. The hydraulic system shall consist of all
fluidpower components necessary for the operation of the forklift,
including the steering system and hydrostatic transmission system but
does not include the brake or the hydrodynamic type power train. All
filler tubes shall be labeled "hydraulic fill". The working hydraulic
system (lift, tilt, fork function and steering) maximum operating
pressure (relief valve setting) shall not exceed 3000 psi and if
furnished, the hydrostatic transmission relief valve setting shall
not exceed 6100 psi. The system fluid shall conform to MIL-L-2104,
grade 10 or MIL-L-46167. All hydraulic system component material
shall be compatible with these fluids. The temperature of the
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