Specifications, Service and Repair of Farm and Lawn Tractors

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John Deere 3120, 3320, 3520, 3720 - PTO

John Deere 3120, 3320, 3520, 3720 Tractor Rear PTO

Testing Rear PTO Knob

Sit on operator’s seat. Lock park brake. Push all PTO engagement knobs to the disengaged/off position. PowrReverser: Depress clutch pedal completely and move the transmission range and gear shift levers to the N (neutral) position. Move the PTO selector lever to the rear PTO only position. Pull the rear PTO engagement knob to the engaged/on position. Turn key switch to start position. Engine must not crank. Push all PTO engagement knobs to the disengaged/off position. Turn key switch to off position.

Testing Rear PTO and Seat Switch Interface

Sit on operator’s seat. Lock park brake. Push all PTO engagement knobs to the disengaged/off position. PowrReverser: Depress clutch pedal completely and: Move the transmission range and gear shift levers into the N (neutral) position. Move the reverser lever to the center neutral position. Start John Deere 3120, 3320, 3520, 3720 engine. Move the PTO selector lever to the rear PTO only position. PowrReverser: Release clutch pedal. Pull the rear PTO engagement knob to the engaged/on position. Raise up from operator’s seat. Do not dismount machine. Engine should stop. Push all PTO engagement knobs to the disengaged/off position. Turn key switch to off position.

Engaging Rear PTO

Stop machine motion and Move the reverser lever to neutral position, and push all PTO engagement knobs to the disengaged/off position (John Deere 3120, 3320, 3520, 3720 with PowrReverser). Remove foot from forward and reverse travel pedals, and push all PTO engagement knobs to the disengaged/off position (eHydro model). The starter will not crank if the rear/mid PTO knob is pulled to the engaged/on position. If the operator leaves the seat with the engine running and the rear/mid PTO engaged, the safety interlock system will stop the engine and all implements. Reduce throttle setting to 1500 rpm. Move the PTO selector lever to top/rearward position for rear PTO only. Pull the rear PTO engagement knob to the engaged/on position to engage the rear PTO. The instrument panel PTO engaged light will illuminate when the rear PTO is engaged. Adjust the hand throttle lever forward to the desired speed for implement used. The PTO marker on the tachometer indicates engine speed for a standard 540 PTO. Disengaging Rear PTO - Adjust engine rpm to low idle. Push all PTO engagement knobs to the disengaged/off position to disengage the rear PTO. The instrument panel PTO engaged light will go out when the rear PTO is disengaged.

Engaging Rear PTO

Move transmission to neutral position: Depress clutch pedal completely and move the transmission gear and range shift levers and the reverser lever to the N (neutral) position (John Deere 3120, 3320, 3520, 3720 tractor with PowrReverser). Move the range shift lever to the N (neutral) position (John Deere 3120, 3320, 3520, 3720 tractor with eHydro). Lock park brake. Push all PTO engagement knobs to the disengaged/off position. The starter will not crank if the rear/mid PTO engagement knob is pulled to the engaged/on position. Start the John Deere 3120, 3320, 3520, 3720 engine and adjust speed to 1500 rpm. Move the PTO selector lever to top/rearward position for rear PTO only. Get off the operator’s seat. Pull the rear PTO engagement knob to the engaged/on position to engage the rear PTO. The engine should continue to run. The instrument panel PTO engaged light will illuminate when the rear PTO is engaged. Adjust the hand throttle lever forward to the desired speed for implement used. The PTO marker on the tachometer indicates engine speed for a standard 540 PTO. Disengaging Rear PTO - Adjust engine rpm to low idle. Push all PTO enagement knobs to the disengaged/off position. The instrument panel PTO engaged light will go out when the rear PTO is disengaged.

Testing Rear PTO and Park Brake Interface

Push all PTO engagement knobs to the disengaged/off position. PowrReverser: Depress clutch pedal completely and: Move the transmission range and gear shift levers into the center N (neutral) position. Move the reverser lever to the center neutral position. Start JD 3120, 3320, 3520, 3720 tractor engine. Set engine speed at 1500 rpm. PowrReverser: Release clutch pedal. Raise up from operator’s seat. Do not dismount machine. Pull the rear PTO engagement knob to the engaged/on position. Rear PTO should operate. Unlock park brake. Engine should stop. Push all PTO engagement knobs to the disengaged/off position. Turn key switch to off position. Using Rear and Mid-PTO (Operator on Seat) - The mid-PTO is available as optional equipment, and is only operational with the operator on the seat. The PTO selector lever has three operating positions: Top (tractors without a cab) or rearward (for tractors with a cab) for rear PTO only. Bottom (tractors without a cab) or forward (for tractors with a cab) for mid-PTO only. Center for both rear and mid-PTO at the same time.

Using Rear PTO (Operator off Seat)

The rear PTO can be engaged with the operator off the seat. The Safety Interlock System will stop the engine and all implements if the mid-PTO is engaged and the operator gets off the seat. The PTO selector lever has three operating positions: Top (tractors without a cab) or rearward (for tractors with a cab) for rear PTO only. Bottom (tractors without a cab) or forward (for tractors with a cab) for mid-PTO only. Center for both rear and mid-PTO at the same time.

John Deere 3120, 3320, 3520, 3720 Tractor Mid-PTO

Testing Mid-PTO and Seat Switch Interface

Push all PTO engagement knobs to the disengaged/off position. PowrReverser: Depress clutch pedal completely and: Move the transmission range and gear shift levers into the N (neutral) position. Move the reverser lever to the center neutral position. Start engine. Set engine speed at 1500 rpm. PowrReverser: Release the clutch. Move the PTO selector lever to the mid-PTO only position. Pull the mid-PTO knob to the engaged/on position. Raise up from operator’s seat. Do not dismount machine. Engine should stop. Push all PTO engagement knobs to the disengaged/off position. Start engine. Set engine speed at 1500 rpm. Move the PTO selector lever to the mid and rear PTO position. Pull the PTO engagement knob to the engaged/on position. Raise up from operator’s seat. Do not dismount machine. Engine should stop. Push all PTO engagement knobs to the disengaged/off position. Turn key switch to off position.

Engaging Mid-PTO

Sit on operator’s seat. Stop machine motion and Move the reverser lever to neutral position (PowrReverser model). Or Remove foot from forward and reverse travel pedals (eHydro model). Push all PTO engagement knobs to the disengaged/off position. The starter will not crank if the rear/mid PTO engagement knob is pulled to the engaged/on position. If the operator leaves the seat with the engine running and the rear PTO engaged, the safety interlock system will stop the engine and all implements. Reduce throttle setting to 1500 rpm. The PTO selector lever has three operating positions: Top (JD 3120, 3320, 3520, 3720 tractors without a cab) or rearward (for JD 3120, 3320, 3520, 3720 tractors with a cab) for rear PTO only. Bottom (tractors without a cab) or forward (for tractors with a cab) for mid-PTO only. Center for both rear and mid-PTO at the same time. Move the PTO selector lever to bottom/forward position for mid-PTO only. Pull the mid-PTO engagement knob to the engaged/on position. The instrument panel PTO engaged light will illuminate when the mid-PTO is engaged. Adjust the hand throttle lever forward to the desired speed for implement used. The PTO marker on the tachometer indicates engine speed for a standard 540 PTO. At 540 rpm rear PTO, mid-PTO speed will be 2100 rpm.

Disengaging Mid-PTO

Adjust John Deere 3120, 3320, 3520, 3720 engine rpm to low idle. Push the mid-PTO engagement knob to the disengaged/off position to disengage the mid-PTO. The instrument panel PTO engaged light will go out when the mid-PTO is disengaged. Engaging Both Rear PTO and Mid-PTO at Same Time - Push all PTO engagement knobs to the disengaged/off position. The starter will not crank if the PTO engagement knob is pulled to the engaged/on position. If the operator leaves the seat with the engine running and the rear PTO engaged, the safety interlock system will stop the engine and all implements. Reduce throttle setting to 1500 rpm. Move the PTO selector lever to center position to operate both rear PTO and mid-PTO at the same time. Pull the PTO engagement knob to the engaged/on position. Two instrument panel PTO engaged lights will illuminate when both PTO’s are engaged. Adjust the hand throttle lever forward to the desired speed for implement used. The PTO marker on the tachometer indicates engine speed for a standard 540 PTO. At 540 rpm rear PTO, mid-PTO speed will be 2100 rpm.

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