TM 5-3895-346-14
INSTALLATION
POWER STEERING
The hydraulic system that is designed to maintain a temperature of 160 or less is desirable.
F
Grade
Table I summarizes the oil types (viscosity and service classification) that are recommended for use with
Vickers equipment. This selection is most important and should be made with considerable care.
TABLE I
API
Service
Hydraulic System
SAE
Classi-
Operating Range
Viscosity
fication
(Min. to Max.)
0 . to 1800F.
F
10W
MS
150F. to 2100F.
20-20W
MS
320F. to 2300F.
30
MS
0 . to 2100F.
F
10W-30
MS
These temperature ranges for each grade of oil are satisfactory if suitable procedures are followed for low
temperature startup conditions and if sustained operation is avoided at the upper temperature limits. For
optimum operation, a maximum oil viscosity of 4000 SSU at the low temperature startup condition and a
minimum oil viscosity of 60 SSU for the sustained high temperature operating condition are recommended.
Operation of the fluid at temperatures below 160 is recommended to obtain the maximum unit and fluid life.
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Automatic Transmission Fluid, Type A is usually satisfactory for power steering systems or those systems
operating under moderate hydraulic service.
POWER STEERING
Miscellaneous
When starting temperatures are below 0 consult the Vickers Sales Representative, Mobile Hydraulics
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Division of Vickers Incorporated.
These oil recommendations are made for the purpose of obtaining maximum service life and performance from
hydraulic pumps and motors.
The performance of hydraulic valves and cylinders is less affected by the lubricating quality of the oil and,
therefore, selection of the oil is less critical. It is always good practice, however, to use the best quality oil
available for all components.
Overload Protection
Relief Valves
An integral relief valve on these units protects the pumps and other units in the hydraulic system from
excessive pressures.
Relief Valve Adjustments Relief valves in the VTM27, VTM41, VTM42, VTM28, and VTM40 pumps are pre-
set at the factory and no field adjustment should be made. If the relief valve setting must be changed, a re-
placement valve should be installed. (Refer to Parts Catalog.)
Pitman Arm Stops
Stops to limit the number of degrees that the Pitman arm can move in either direction should be installed with
all pumps in this series. The stops should be properly adjusted to prevent excessive thrust and cramping of the
steer- ing linkage which causes excessive pump relief valve operation.
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