1991/12/01 Caterpillar

Service Parts Available for 838440 Joystick Controller Group. Procedure to Recalibrate the Joystick{5485}


RT50...4XG, RTC60...5PF, RT60...5DG, RT50 SA...8DJ

Reference: Lift Truck Technical Bulletin; this edition, "Checking The 838440 Joystick Group".

The 838440 Joystick Controller Group, part of 815916 Cab Electrical Group, is now serviceable. See the chart and illustration.

The 838440 Joystick has a redesigned top boot and housing for improved sealing. The boot listed in the chart is the new style and is not retro-fittable to the old style housing. All other parts are interchangeable.

Whenever changing components within the Joystick Controller, the possibility exists that calibration may be necessary. Use the following procedure to recalibrate the Joystick.

1. Remove the 6R9288 Lock Ring from the base of the joystick and slide the plastic cowling off the joystick harness.

2. Once the cowling has been removed, the four potentiometers are visible. These govern the "boom up, boom down, tele in and tele out" functions. The two fork motion potentiometers are mounted in the joysitck hand-grip.

3. Using a 6V7070 Digital Multimeter or equivalent, turn the indicator to the 2K OHM range. Connect the common lead to the no. 1 connector and the V-OHM lead to each of the following leads and measure the resistance.

4. The resistance measured should be 210 OHMS with the joystick or push button fully stroked. If the resistance reading is out of specification on one of the four lower joystick potentiometers, adjust the nuts and screws that are part of the 6R9287 slider/push rod kit, until the proper resistance is read.

5. To adjust the carriage tilt function:

a. Remove the four screws under the joystick head and carfully separate the head assembly from the joystick.

b. Notice the stops, (8Q2687), limit the travel of the contact on the potentiometer.

c. If the resistace is too high, a small amount of the stop must be removed. Using a small file, remove a small amount of material from the stop.

d. Check the resistance and repeat if necessary.

e. If the resistance is too low, the stop, (8Q2687), should be replaced. Repeat the procedure to check the resistance and adjust as required.

6. When the joystick controller is calibrated, install a 838441 calibration sticker on the outside surface of the joystick.

7. After installing the calibrated joystick, perform the setting instruction for the electronic control box group given in Special Instruction SEHS6144.

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