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John Deere 3120, 3320, 3520, 3720 - Service Transmission

John Deere 3120, 3320, 3520, 3720 Tractor Front Axle

Checking Front Axle Oil Level

Allow John Deere 3120, 3320, 3520, 3720 tractor to cool down for at least one hour. Dirt and debris in oil may cause damage to the transaxle. Clean area around opening before removing dipstick. Loosen and remove dipstick located on right side of front axle. Wipe dipstick clean with a rag. Install and tighten dipstick. Remove dipstick again. Oil level should be indicated on the dipstick, but not above the full line. If oil level is low: Add recommended oil through dipstick fill opening until oil level is correct. Install and tighten dipstick. Check front axle oil level again after the first several hours of operation.

Changing Front Axle Oil

Operate JD 3120, 3320, 3520, 3720 tractor to warm front axle oil. Park machine safely. Position drain pan under differential drain plug. The front axle contains approximately 5.0 L (1.3 gal) of oil. Remove differential drain plug and allow oil to drain. Position drain pan under axle drain plug on both sides of front axle. Remove axle drain plugs and allow oil to drain. Install and tighten all three drain plugs after all oil has drained. Remove dipstick located on right side of front axle. Add approximately 5.0L (1.3 gal) of recommended oil into dipstick filler opening. Install and tighten dipstick. Check front axle oil level.

Adjusting Front Axle Thrust Bolt Torque

Adjust bolt torque at the required service interval to prevent excessive forward and rearward movement of the front axle. Raise front axle off ground to take machine weight off the front axle. Loosen jam nut. Tighten bolt to 32 Nm (24 lb-ft). Do not overtighten. Tighten back the jam nut. Lower front axle back to ground.

John Deere 3120, 3320, 3520, 3720 Tractor Transmission

Checking Transmission Oil Level

Allow machine to cool down for at least one hour. Remove dipstick located behind operator’s seat. Wipe dipstick with a clean rag. Install dipstick. Remove dipstick and check oil level. Oil level should be between the minimum and maximum lines. Clean area around fill cap before removing. Do not overfill transmission. Oil expands during operation and could overflow. If oil level is low: Remove oil fill cap. Add recommended oil at fill cap location. Install and tighten fill cap.

Changing Transmission Oil and Hydraulic Suction Oil Filter

Run John Deere 3120, 3320, 3520, 3720 engine a few minutes to warm the transmission oil. Position drain pan under transmission drain plug and suction filter assembly on left side of transmission. Remove plug and allow oil to drain. Remove cover and allow oil to drain. Remove filter assembly and replace with new filter assembly. Install cover. Install transmission drain plug. The inline hydraulic filter should be cleaned at the same time the transmission oil is changed, but not every time. Clean inline hydraulic filter: Position drain pan under filter. Remove filter from lines. Remove nut with internal element from case. Clean case and internal element with a mild solvent. Allow to dry. Direction-of-flow arrow on filter points toward transmission fitting. Assemble and install hydraulic filter assembly. Remove fill cap. Add recommended oil into filler opening. Start engine. Check for oil leaks around filter base and drain plugs. Stop engine. Check transmission oil level.

John Deere 3120, 3320, 3520, 3720 Tractor with PowrReverser Transmission

The range shift lever provides three speed ranges. The gear shift lever provides four gear positions. The reverser lever controls travel direction. Use all three levers in different combinations to achieve twelve forward and twelve reverse speeds. Machine motion must stop and the clutch pedal must be depressed before changing ranges. Gears may be changed while machine is in motion if clutch pedal is completely depressed. Select the proper speed range and gear for the job: Never overload engine by lugging machine at low idle speeds. Raise engine speed to match expected loads. If a slight increase in engine rpm occurs simultaneously with moving hand throttle lever forward, the engine is not overloaded. Choose a speed range to match work application: Low speed/high power operations such as tilling hard soil, mowing high grass or positioning backhoe. Operations including moderate tilling, hauling, and grass mowing. High speed operations such as transport and light mowing. Choose a gear that matches the immediate power/speed requirements: 1st Gear – High power, low speed operations. 2nd Gear – Medium power, moderate speed operations. 3rd Gear – Low power, moderate speed operations. 4th Gear – Low power, high speed operations.

Driving Machine (PowrReverser)

Start JD 3120, 3320, 3520, 3720 engine. Move reverser lever to neutral position. Unlock park brake. Depress clutch pedal completely. Choose speed range on transmission range shift lever to match work application. Move the transmission gear shift lever to the desired gear position. Move the reverser lever to the forward or reverse position. Release clutch pedal gradually to take up load smoothly. Continue to shift gears while moving under normal loads: Depress clutch pedal completely and shift to next gear. Release clutch pedal gradually to take up load smoothly. Adjust throttle speed: To maintain a constant operating speed, adjust the engine speed with the hand throttle lever. To repeatedly increase and decrease engine speed, leave the hand throttle lever set at the middle position and use the foot throttle to change engine speed. To change travel direction: Clutch use is not required. Move the reverser lever to the forward or reverse position.

John Deere 3120, 3320, 3520, 3720 Tractor with Hydro Transmission

The range shift lever provides three speed ranges. The range shift lever is used in conjunction with the forward and reverse travel pedals. Select the proper speed range and gear for the job: Never overload engine by lugging machine at low idle speeds. Raise engine speed to match expected loads. If a slight increase in engine rpm occurs simultaneously with moving hand throttle lever forward, the engine is not overloaded. Choose a speed range to match work application. Low speed/high power operations such as tilling hard soil, mowing high grass or positioning backhoe. Operations including moderate tilling, hauling, and grass mowing. High speed operations such as transport and light mowing.

Driving Machine (eHydro)

Start machine engine. Unlock park brake. Choose speed range on transmission range shift lever to match work application. Move hand throttle lever to desired operating speed. Slowly depress forward pedal downward to travel forward. Slowly depress reverse pedal downward to travel in reverse. The farther either travel pedal is depressed, the faster the machine will travel. Release travel pedal to stop machine and change speed range. Fully stop machine motion before turning off ignition.