ORBITROL SERVICE MANUAL (CONT)

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

difficulty.

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

steering.

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

attention.

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

of either

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