4. Verify the steering cylinder does not move, when steering wheel is untouched.
The number of turns on steering wheel must match the following calculation:
i approximately or equal to V/Vvs where V is stroke volume of steering cylinder, ccm Vvs equals OSQ
steering system displacement, ccm/rev
V, stroke volume if cylinder in test rig: 4000 ccm
Vvs, steering system displacement with OSQ 5 and OSPBX 200 LS: 1000 ccm/rev
Greater than i, approximately or equal to 4000/1000, equal to 4 turns lock to lock
Pilot relief valve
The pump flow is adjusted to approximately 140 l/min and pressure to maximum 240 bar.
The steering wheel is actuated until the steering cylinder reaches one of its end strokes and the steering
wheel is actuated in this cylinder position with steering torque 20 ± 5 Nm.
The pilot relief valve (item 23 of exploded view) is set according to specification: Maximum steering
pressure (P-T), bar, for the code in question.
The setting pressure is the pressure on the HP-port minus the HT-port of OSQ.
Neutral positioning
After adjusting the pilot relief valve, the steering wheel must be able to go to neutral position by itself no
later than approximately 1 second after the activation of the steering wheel has been stopped.
The steering unit and OSQ are properly in neutral position when the pressure drop (HP-HT of OSQ) is no
higher than 30 bar at pump flow 140 l/min, and there must be no movement of the steering cylinder.
Manual steering test
Without pressure on HP and HT ports, the OSPBX and OSQ must be able to steer in a smooth manner to
the right and to the left observed by the cylinder movement.
The number of turns on the steering wheel for moving the steering cylinder from lock to lock, must
increase in comparison to do this test with normal pump supply.
Without pump supply the number of turns must match cylinder volume/displacement of OSPBX.
Cylinder volume: 4000 ccm and OSPBX 200 LS greater than number of turns must
be 4000/200 which is approximately or equal to 20 turns.
Service Manual
OSQA/OSQB
Testing
©
Danfoss | July 2016 HN25D293 | AX00000127en-US0101 | 41
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General