1600220, OPR, HYSTER, Hyster2, SRM

//-->.pos {position:absolute; z-index: 0; left: 0px; top: 0px;}INTRODUCTIONGENERALThis section has the description, operation, checks andadjustments for the parts of the electric power steering(EPS) system. The system electrically controls a motorto turn the master drive unit for steering. This section isNOT for lift trucks that have the wire guidance system.See the sectionsWIRE GUIDANCE, DE-SCRIPTION, 2200 SRM 317,section to adjust orWIRE GUIDANCE, REPAIR, 2200 SRM 321,to re-pair the parts of the EPS system used on lift trucks withwire guidance.to turn the drive sprocket. The drive sprocket movesthe chain to turn the MDU on the spindle. The steeringpotentiometer is turned by a gear on the MDU spindle.The potentiometer tells the ECM the position of theMDU.DESCRIPTION (See FIGURE 1.)The electric power steering system has no cables or hy-draulic lines between the steering wheel and the MasterDrive Unit (MDU). The system uses electrical signalsto control an electric motor and gear box to turn theMDU. An electrical signal generated by turning thesteering wheel is an input to a control module that oper-ates the motor. Other inputs are also used for correctsteering control.The following parts are in the system:a. Steering wheel, gears and steering generatorb. Two wires in an 18 conductor cable between thesteering generator and electrical compartmentc. The Electronic Control Module (ECM)d. The electric motor, worm reduction gear andchain to the MDUe. The steering potentiometerf. The automatic shut–off card.The speed and direction of rotation of the steeringwheel sets the voltage and polarity of the generator sig-nal. The generator signal varies from zero to a plus vol-tage and from zero to a minus voltage to indicate steer-ing rate and direction. The steering wheel and gearsturn the shaft of the signal generator. The ECM uses theinputs from the steering generator and steering poten-tiometer to control the power to the steering motor.The ECM is fastened to the electrical compartmentdoor or panel. The door or panel is a heat sink for themodule. The steering motor is a permanent magnet mo-tor. The steering motor turns the worm reduction gear110281.2.3.4.5.6.7.8.9.10.MULTIPLE CONDUCTOR CABLESTEERING WHEELSTEERING GENERATORTRACTION CIRCUITAUTOMATIC SHUT–OFF CARDELECTRONIC CONTROLMODULEBATTERYSTEERING MOTOR AND GEARBOXSTEERING POTENTIOMETERMDU AND CHAINFIGURE 1. ELECTRIC POWER STEERINGPARTSOPERATIONRotation of the steering wheel turns the gears and thesteering generator shaft. The generator voltage, indi-cating the direction and rate of rotation, goes to theelectronic control module (ECM). The ECM knows theposition of the MDU from the signal of the steering po-tentiometer. The ECM sends a signal to the steeringmotor to turn the MDU. The steering potentiometerchecks that the MDU moves correctly.If the MDU does not move correctly, the ECM sends asignal to the automatic shut–off board. The automaticshut–off circuit sends a signal to the traction controlcircuit. The signal will deenergize the traction circuitand apply the brake. After shut–off occurs, the systemmust be reset by moving the key to the OFF position.Energize the electrical system to continue operation.1CHECKS, ADJUSTMENTS AND TEST PROCEDURESGENERALWARNINGMany checks and adjustments are done with the bat-tery connected. Never have any metal on your fin-gers, arms or neck. During some checks or adjust-ments the operator must move the truck. The persondoing the adjustments must make the adjustmentswith the system energized. Make sure the operatordoes not move the truck to cause an injury.The EPS system uses the ECM test circuit to check forcorrect operation and adjustment of the parts of the sys-tem. The test circuit automatically makes some checksduring operation. Other checks can be done manually.These last checks are normally necessary as part of theadjustment procedures. The checks are found in theADJUSTMENTS and TEST PROCEDURES of thissection. The Test push button, on the ECM circuitboard, is used to change to the next manual test. Thedisplay, LED 1 and LED 2, on the ECM circuit board,indicate the results of the tests. See FIGURE 2. TheECM test circuit has the following sequence for the themanual tests: 1 and 2.NOTE:The ECM display will show an “E” if the auto-matic shut–off circuit has operated to prevent lift truckmovement.Automatic ChecksThe logic system of the ECM makes internal checks forcorrect operation. The checks are automatic and occurduring steering.Program Memory ChecksumThis automatic test checks the program memory of theECM each time the guidance system is energized.During the first half–second after the electrical systemof the lift truck is energized, the display will show an“F”. If the display shows a “C”, the contents of thememory are not correct. The steering system will notoperate and the system program needs a correction. Re-set the system by moving the key to the Off position,then back to the On position. If the display again showsa “C” when the system is energized, replace the ECMlogic board. The display will show the numbers as de-scribed in Normal Display if there is no “C”.Watchdog ResetThis automatic test checks for faults that can reset theECM. These faults normally occur only once. The lifttruck will continue to operate and the display will showan “8” to indicate a possible problem. The “8” displaycan be a guide to the service person if a malfunctiondoes not occur at a regular interval. The fault can be atemporary poor connection.Normal DisplayThe display will show one of the following numbersduring normal operation.0 – The steering wheel is not turning.NOTE:The following display numbers are constantlychanging. Read the average number.1 or more – The operator is turning the steeringwheel (display number times 6.25 is the steeringmotor current).115861. DISPLAY2. TEST BUTTON3. LED 14. LED 2FIGURE 2. ECM CIRCUIT BOARDCHECKSThe following paragraphs have a description of the au-tomatic checks that are done by the test circuit of theECM. There is also a description of the numbers andletters on the ECM display during normal operation.2ADJUSTMENTSGeneralNOTE:Never adjust the EPS system if the system oper-ates correctly.Adjustment of the Steering Chain(See FIGURE 3.)1. Open the electrical compartment doors and makesure the MDU is in position for straight travel. Makesure the steering chain is tight on the section of chainnear the battery.2. Operate the steering to find the point where the steer-ing chain has the least clearance. Move the steeringwheel to turn the MDU to the full CW position. Slowlyturn the MDU in the CCW direction and watch thesteering chain. The point of least clearance is the pointwhere the steering chain is straight or nearly straightbetween the sprockets.1.3 TO 3.3 mm (0.05 TO 0.13 in)WARNINGSome of the adjustments are done with the batteryconnected. Never have any metal on your fingers,arms or neck. These metal items can accidentlymake an electrical connection and cause an injury.WARNINGDuring some of the adjustments, the operator mustmove the lift truck. The person doing the adjust-ments must make the adjustments with the systemenergized. Make sure the operator does not move thelift truck to cause an injury.A malfunction of a separate part in the steering systemcan prevent correct electrical adjustment of the EPSsystem. All parts must be installed correctly andchecked for correct operation.SET UP PROCEDURES FOR EPSDuring the adjustment and test procedures, you willhave instructions to set the lift truck or lift truck systemfor different functions. The following are the correctprocedures:To Energize The Lift Truck Electrical System:a. Connect the battery to the lift truck.b. Make sure all gate, side rail or brake switches areclosed. Move the key switch to the ONandSTART positions.To Deenergize The Lift Truck Electrical System:a. Disconnect the battery from the lift truck. Sepa-rate the battery connector.b. Discharge all capacitors on the lift truck that re-main charged after disconnecting the battery.These capacitors can be capacitor 1C in the SCRtraction and hydraulic control systems.To Energize The Manual Test Function:a. Energize the lift truck electrical system.b. Push the Test button on the ECM circuit board.30721. REDUCER SPROCKET2. STEERING CHAIN3. MDU SPROCKET4. ADJUSTING NUT5. ADJUSTING BOLT6. RIGID MATERIALFIGURE 3. ADJUSTING THE STEERING CHAIN3. Install a thin piece of rigid material on the chain be-tween the sprockets. The material must have a straightedge. Make sure the chain is tight on the opposite sideof the sprockets. Measure the clearance between thebottom of the straight edge of the rigid material and thechain. See FIGURE 3. The middle of the chain musthave a clearance of 1.3 to 3.3 mm (0.05 to 0.13 in).4. Tighten the adjusting nut at the MDU sprocket for amaximum clearance of 1.3 to 3.3 mm (0.05 to 0.13 in)between the chain and straight edge. Do NOT tightenthe adjusting nut for a clearance of less than 1.3 mm(0.05 in).5. Close and fasten the electrical compartment doors.3TORQUE122 to 136 N.m(90 to 100lbfft)110291. STEERING POTENTIOMETER2. BRACKET, POTENTIOMETER3. MOUNT SCREWS FORPOTENTIOMETER4. MDU GEAR5.6.7.8.POTENTIOMETER PINIONSTOP SCREWLIMIT SWITCH LS7LIMIT SWITCH LS59.10.11.12.LOCK NUTBRAKE DRUMSIDE PLATEBRACKET ASSEMBLYFIGURE 4. STEERING POTENTIOMETER AND LIMIT SWITCH ADJUSTMENTAdjusting Limit Switches (See FIGURE 4.)Adjustment of the Steering Potentiometer(See FIGURE 4. and FIGURE 6.)1. Align the MDU by measuring the distance betweenthe brake drum and the frame side plate on each side ofthe brake drum. See FIGURE 4. Adjust the MDU sothat these measurements are equal. Use a large screw-driver to turn the armature shaft of the steering motor toalign the MDU.2. Energize the lift truck electrical system. Push theTest button on the ECM. Make sure there is a “2” on thedisplay.3. If the ECM has an R58 potentiometer, adjust R58 fora flashing LED 2 on the ECM board. If the ECM doesnot have an R58 potentiometer, rotate the steering po-tentiometer housing for this adjustment.NOTE:Do not touch the terminals on the steering po-tentiometer while making adjustments. Touching theterminals will cause an incorrect reading.NOTE:If the results are not correct for step 3, do step 4.4. Rotate the steering potentiometer housing to the cen-ter position of the adjustment range of the mount.1. Align the MDU by measuring the distance betweenthe brake drum and the frame side plate on each side ofthe brake drum. See FIGURE 4. Adjust the MDU sothat these measurements are equal. Use a large screw-driver to turn the armature shaft of the steering motor toalign the MDU.2. Use washers to align the limit switch and potentiom-eter bracket. The limit switch rollers and the poten-tiometer pinion gear must be aligned with the MDUgear weldment.3. If necessary, bend the tabs on the lock washer toloosen the lock nut to move the gear weldment. Alignthe gear weldment and tighten the lock nut to 68 to 102N.m (50 to 75 lbf ft) torque. Do not let the gear weld-ment or MDU move as the lock nut is tightened.4. Bend at least one tab of the lock washer into the holeof the gear weldment and one tab into the lock nut.45. Push the Test button on the ECM for a “2” on the dis-play. Loosen the stop screw for the steering potentiom-eter. Move the steering potentiometer away from thedrive gear. Rotate the potentiometer pinion for a flash-ing LED 2. Engage the pinion. Adjust the stop screwfor a clearance of 0.8 to 1.0 mm (0.030 to 0.040 in) atthe point of minimum clearance. Repeat step 3.age. Clean the battery and battery compartment as ne-cessary. There can also be a voltage on the frame ifthere is carbon dust in the motors. Use dry compressedair to remove the carbon dust from all motors.Steering GeneratorChecksThere are two procedures to check for correct operationof the component. The first check uses the manual testof the ECM test circuit. The second procedure uses adigital voltmeter.ECM Manual Test:NOTE:The steer wheel will not move during this test.Energize the the electrical system and push the Testbutton for a “1” on the ECM display. Make sure LED 1is On and LED 2 is Off. Have the operator turn thesteering wheel to steer the lift truck in the 9:00 clockdirection first. Then, turn the steering wheel for a turnin the 3:00 clock direction. See FIGURE 5. This se-quence of steering wheel rotation must be followed.LED 1 must be Off and LED 2 must be On when the lifttruck steers toward the 9:00 clock direction. LED 1 andLED 2 must both be On for the 3:00 clock direction. Ifthe results are not correct, move the key to the OFFposition to reset the system and do the VoltmeterCheck.TEST PROCEDURESChecking For Short–Circuit To FrameGeneralIt is important for the correct operation of the EPS sys-tem that all system components have electrical insula-tion. There must be electrical insulation between theframe of the lift truck and each component. If a connec-tor, cable, wire or component is making a connection tothe frame, a malfunction can occur. The position of amotor cable can make a magnetic field that can changethe the signals to the ECM. Electrical static can alsocause a malfunction. Make sure all cables are installedin the same position that they were in before removal.Make sure all shields are correctly installed and con-nected. Make sure all insulation and isolators are cor-rectly installed. Repair all short–circuits as soon as theyare found. Keep the battery and battery compartmentclean and painted. Keep all carbon dust and dirt re-moved from the inside of all the motors. Use dry com-pressed air.Checks1. To check for wire connections to the frame, discon-nect the battery. Use an ohmmeter to check the circuits.Check for 50,000 ohms or more between each terminalof the battery connector for the lift truck and a cleanconnection on the frame. Make sure there are no elec-trical connections to the frame of the lift truck. Wires orterminals without insulation can cause these connec-tions.2. Check for voltage between each terminal of the con-nector to the battery and a clean metal connection onthe frame of the lift truck. It is normal to measure somevoltage between the battery and the frame even if theresistance checks are correct. There can be a voltage onthe frame if the battery is dirty or the battery has dam-LOAD WHEEL11557STEER WHEELFIGURE 5.LIFT TRUCK DIRECTIONORIENTATIONVoltmeter Check:The following tests can be made at both the steeringgenerator and at the ECM board. Do the checks at the5

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