of these. Check or adjust to the vehicle manufacturer's
and replace as much of the oil as possible; crank the pump
recommended pressure setting.
over by hand to exhaust oil from it and swing the cylinder
through a full travel; but do not forcibly rotate the
If the system is reported to operate extremely hot,
ORBITROL steering wheel if a dirty fluid is suspected.
connect a pressure gage as above and operate the engine
Refill the system with clean oil, run the system briefly
at near full throttle. Rotate the steering wheel slowly in
recheck and refill as necessary to obtain proper fluid level.
each direction and bring the wheel to the position that
Operate the system for a short time to determine whether a
shows the lowest pressure reading. This places the control
correction has resulted. It is sometimes less costly to rinse
section of the unit in neutral. Then turn the steering wheel
and reclean the system twice than to completely tear down
to a limit stop and hold it there for one to two seconds.
and reassemble a unit and the clean fluid will definitely
Release the steering wheel gently and watch the gage. If
protect all of the components of the system.
the pressure does not drop to very nearly the same neutral
pressure as measured when placing the control in neutral
In the functional check, determine also that the
deliberately, a binding control shaft or dirt between the
actuating cylinder achieves full travel without hesitation. If
spool and sleeve of the control valve can be the cause of
the cylinder seems to pause in its travel while it should .be
moving smoothly, this may indicate that it contains trapped
air. In filling and refilling a system, it is sometimes
If the reentering characteristic as measured above is
necessary to lift the vehicle weight off the steered axle or
erratic and if the control feels slightly sticky through most
to remove the cylinder and hold it in a position so that the
of the travel, apply the pressure gage in the "OUT" line of
ports are uppermost so that air will be bled back to the
the ORBITROL. This return line pressure should be below
system reservoir and effectively exhausted from the
30 psi during all periods of normal operation. Check this
system at the reservoir vent. During this inspection,
"downstream" line to insure that no fittings are obstructed.
determine that the mechanical or other limit stops at the
If the system uses a return line filter, as in many common
axle are functioning properly. Proper wheel alignment is
power steering pump tank units, a higher return line
every bit as important on power-steered vehicles as on any
pressure may indicate that the filter needs cleaning.
other to insure satisfactory tire life and geometrically true
If after the Inspections described, a functional
Inspect to insure that the system has adequate power.
difficulty Is Indicated in the ORBITROL, Char-Lynn
Some machines are designed so that they can not be
Company maintains a complete service and repair
steered unless they are rolling. Most, though, will steer
department so that your unit, shipped to 15151
completely while standing still on a smooth hard surface. If
Highway 5, Eden Prairie, Minnesota, and togged
there is an indication of "hard-steering", this can indicate
"Repair and Return," will receive prompt, skilled
either a reduced oil flow to the control or a reduced system
relief pressure. Adequate oil flow under all conditions can
best be checked by timing the full travel of the cylinder with
If instead you need or wish to accomplish repairs within
the steered axle unloaded and loaded. If there is a great
the unit, use the following procedure for disassembly,
difference at low engine and slight difference at high
inspection and reassembly.
engine speed, this may indicate a defective pump drive.
Adequate oil pressure can only be determined by
connecting a pressure gage (2000 psi full scale
recommended) at the pump outlet port or at the "IN" port of
the ORBITROL. With the engine running at a medium
speed, turn the steering wheel to one end of the travel and
hold the cylinder at the travel limit briefly - just long enough
to read the pressure gage. Never hold a system at relief
pressure for more than a few seconds at a time. Longer
operation at relief pressure can overheat most systems
quite rapidly. The pressure relief valve is a protection for
all of the various parts of the steering system. There is no
pressure relief in the ORBITROL. Power steering pressure
relief valves are usually located in the power steering
pump or flow control valve or very near the discharge line