1600177, OPR, HYSTER, Hyster2, SRM

//-->.pos {position:absolute; z-index: 0; left: 0px; top: 0px;}INTRODUCTIONGENERALThis section has a description and the repair procedures forthe steering control unit. A troubleshooting guide is at theend of the section. The Checks and Adjustments section hasa test procedure for checking the operation of the differentparts of the steering system.The control valve section controls the amount of oil from thegear pump that enters the inlet to the manually operated pump.The control valve section and metering section of the steer-ing control unit are connected both mechanically and hy-draulically.The control valve section has a rotary spool that opens thepassage from the supply port to the metering section whenthe steering wheel is turned. From the metering section, theoil flows back to the rotary spool. The control valve thensends the oil to the correct end of the steering cylinder. Therotary spool also transfers the return oil from the steeringcylinder to the oil tank.The rotary spool moves from the neutral position when thesteering wheel is turned. When the rotary spool rotates asmall amount, certain ports are aligned. Two leaf springs forthe rotary spool are twisted a small amount when the steeringwheel is turned. Because of the leaf springs, the rotary spoolreturns to the neutral position when the steering wheel isstopped. In the neutral position, oil from the pump flowsthrough the control valve to the tank. The ports to the steer-ing cylinder are closed in the neutral position to prevent move-ment of the steering cylinder piston.The metering section has a port ring and manifold and a manu-ally operated pump with an inner and an outer rotor. Theinner rotor is prevented from turning by the leaf springs anddrive link. The outer rotor is fastened to the input shaft forthe steering wheel. When the steering wheel is turned, thelobes of the outer rotor cause oscillations of the inner rotor.Oil flows into the metering pump from the control valve, portring and manifold. When the input shaft is turned, a lobe ofthe inner rotor moves the oil from the space between twolobes of the outer rotor. The manifold and port ring transferthe oil from between the lobes back to the rotary spool. Themetering section acts as a hydraulic motor that is controlledby the rotary spool valve.The amount of oil that flows to the steering cylinder iscontrolled by the metering section. Only the volume ofoil moved by the metering pump will flow to the steer-i n g c y l i n d e r. B e c a u s e t h e v o l u m e m o v e dFIGURE 1. STEERING CONTROL UNITDESCRIPTION AND OPERATIONThe steering system uses a gear pump with a flow controlvalve and a relief valve to supply oil to the steering controlunit. The steering control unit has a metering pump that ismanually operated by the steering wheel. The metering pumpuses oil from the gear pump to help it operate. The meteringpump in the steering control unit has oil with pressure at theinlet to make it easy to move oil to the steering cylinder. Themetering section of the steering control unit controls theamount of oil transferred to the steering cylinder.1. FLOW REGULATOR2. RELIEF VALVE3. HYDRAULIC TANK4. SCREEN5. ENGINE6. GEAR PUMP ASSEMBLY7. STEERING TEST PORT8. STEERING CONTROL UNIT9. STEERING CYLINDER10. FILTER11. FROM MAIN CONTROL VALVE12. TO MAIN CONTROL VALVEFIGURE 2. STEERING SYSTEM SCHEMATIC1. NUT2. DUST SEAL3. RETAINER RING4. BACK RING5. SEAL6. 12 POINT CAPSCREW (8)7. UPPER COVER8. O-RING9. THRUST WASHER10.THRUST BEARING11.INPUT SHAFT12.ROTOR SETA. OUTER ROTORB. INNER ROTORC. SPRING (6)D. VANE (6)13.SPACER14.DRIVE LINK15.PINS16.MANIFOLD AND WASHER17.12 POINT CAPSCREW (7)18.SEAL19. PORT RING20. COUPLER21. ROTARY SPOOL22. LEAF SPRINGS23. ADJUSTER SCREW24. O-RING25. HOUSING26. BALL27. O-RING28. PLUG29. O-RING30. SPECIAL PLUG31. LOCK NUT32. CAPFIGURE 3. PARTS OF THE STEERING CONTROL UNITby one revolution of the steering wheel is constant, theposition of the steering wheel is aligned with the position ofthe wheels.The metering pump can move oil to the steering cylindereven when the main hydraulic pump is not operating. Moreforce is needed to turn the steering wheel but the alignmentstays the same. A checkvalve permits the return oil from thecylinder to flow to the metering pump inlet when the engine isstopped and the steering wheel is turned.The oil returning from the steering cylinder to the tank doesnot flow through the metering section. The oil flows from thesteering cylinder to a port on the control valve. The oil thenflows through the rotary valve to the “OUT” port for the tank.FIGURE 4. HYDRAULIC SYSTEMREPAIRSREMOVALA. Remove the rubber cover from the steering wheel. Re-move the lock ring and horn assembly. Disconnect the wirefor the horn.B. Remove the nut from the steering shaft. Use a puller toremove the steering wheel.C. Remove the linkage for the direction control lever. Removethe two capscrews from the clamp for the direction controllever.A. Clean the outside of the steering control unit before disas-sembly.B. Remove the horn contact from the steering column. Loosenthe clamp on the steering column. Remove the steering col-umn from the steering control unit.C. Remove the retainers that hold the pins in the shaft. Pushthe pins from the shaft with a press. Remove the shaft.CAUTIONDamage to the thrust bearings can occur if a ham-mer is used to remove the pins.D. Use a vise to hold the steering control unit for disassem-bly.CAUTIONDo not put the housing between the jaws of thevise. The vise must hold a fitting that is installedin the steering control unit. See Figure 6.FIGURE 5. STEERING COLUMN ASSEMBLYD. Disconnect the hose fittings from the steering controlunit. Put caps on all the fittings. Remove the clamp that holdsthe steering column to the instrument panel. Disconnect thehorn wire.E. Remove the capscrews from the bracket that holds thesteering control unit. Remove the steering column with thesteering control unit.FIGURE 6. HOLDING HOUSING USING FITTINGDISASSEMBLYWARNINGThe clearances in the steering control unit arevery small. Care must be used in cleaning andthe handling the parts. Dirt in the control unitcan keep the steering wheel from turning in thecorrect direction.E. Use a screwdriver to remove the dust seal. See Figure 7.Clean the shaft of any paint or corrosion.F. Put a drain pan under the steering control unit. Remove the8 special capscrews with a 1 /4 inch 12 point socket. SeeFigure 8.

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