FORM NO. 56043107 - Advolution
™
2710 / UHR 70-1700 - 35
WHEEL DRIVE SYSTEM
POTENTIOMETER REMOVAL AND TESTING
WARNING!
Disconnect the battery pack by separating the battery connectors (7) whenever servicing the machine.
Potentiometer Removal
1 See Figure 10. Remove the (5) Screws (A) securing the drive pedal mount assembly to the chassis then carefully lift the pedal assembly up
and lay it on its side.
2 Observe the (3) wires connected to the Drive Pedal Potentiometer (pot) (B) and also the single GRN/YEL throttle ground wire (C), note the
proper wire colors and their terminal connections for re-assembly. Then disconnect wiring and remove the pedal mount assembly from the
machine.
3 Remove the Link Rod (D) from the Pedal (E). Note: Be careful not to lose the link rod mounting hardware items (F).
4 Loosen the Nut (G) and Screw (H) at the drive pedal Throttle Lever (I). Then pry the lever off from the end of the item (B) potentiometer
shaft. Next remove the pot from the Mount Housing (J).
Testing the Potentiometer
Note: The pot doesn’t have to be removed from the housing to test.
1 Test the potentiometer using an Ohmmeter (the pot specifi cation is 5K Ohms).
2 Connect the meter leads to each of the outside connections on the potentiometer. The meter should read approximately 5000 Ohms (plus or
minus 500 Ohms).
3 Next, move one of the test leads to the middle connection and turn the stem in both directions. The range of the readings should be
approximately 1300-2500 Ohms or 2500-3700 Ohms increasing and decreasing through its full range.
4 If you do not get these readings replace the potentiometer.
Technical Service Tip: A simple short cut method for testing and adjusting the pot resistance values is at the speed controller’s 18 pin plug. Just
disconnect plug and back probe pins 3, 4 & 13 (wire colors VIO/BRN, GRA and BRN/BLK). The controller can be easily accessed by removing the
electrical panel door located in the operator’s compartment.
POTENTIOMETER INSTALLATION AND ADJUSTMENT:
WARNING!
The adjustment of the potentiometer is to set the drive pedal for a neutral drive motor operation. If the pot is not adjusted properly, the machine
will creep in either FWD or REV.
1 See Figure 10. Install the pot into the Mount Housing (J) and tighten the attachment nut.
2 Connect together loosely both the Link Rod (D) to the Pedal (E), and the Throttle Lever (I) to the potentiometer input shaft. Then tighten only
the Link Rod (D) pedal mounting Hardware (F). Note: Check the movement of the Foot Pedal (E) it must move freely in both Fwd and Rev.
3 See Figure 10 inset. Attach test leads from a volt/ohm meter to the VIO/BRN and BRN/BLK wire connection points on the potentiometer to
check it’s total resistance (example 4800 Ohms).
4 Next connect the ohmmeter test leads to the VIO/BRN and GRA potentiometer connection points. Then using a small screwdriver, turn the
shaft end on the pot to half the total resistance previously measured. Example: 4800 Ohms divided by 2 = 2400 Ohms. Then without turning
the shaft, tighten the Screw (H) and Nut (G) to secure the setting at the Throttle Lever (I).
5 Follow steps 1-2 in reverse order (see Potentiometer Removal steps) to fi nish the installation. Then test-drive the machine for proper speed
and FWD/REV directional control.
ALTERNATE METHOD FOR THROTTLE ADJUSTMENT
The throttle adjustment is easier and more accurately adjusted by measuring the throttle potentiometer wiper voltage with respect to B (-).
To set throttle neutral:
1 See Figure 11. Connect a voltmeter to B (-) on the speed controller and the GRA wire. A thin probe can be inserted into the connector at pin
4 on the speed controller, or an insulation piercing probe can be used on the GRA wire.
2 Adjust the throttle potentiometer to 2.50 +/- .05 volts with the throttle pedal in neutral.
This will insure that the throttle is centered on neutral and there is 100% throttle when the pedal is fully depressed in the forward direction. A
Curtis programmer can be used to check that there is 100% throttle in forward.
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