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John Deere 3120, 3320, 3520, 3720 - Service Brakes and Wheels

John Deere 3120, 3320, 3520, 3720 Tractor Brakes

John Deere 3120, 3320, 3520, 3720 Tractor Without Cab. Adjusting Brake (Pedals) - Loosen jam nuts on brake linkage and adjust each turnbuckle so there is about 22-30 mm (0.87-1.2 in.) of free play at the pedals. Check to be sure free play is about the same for both pedals. Tighten jam nuts to lock in place. Adjust park brake linkage. Adjusting Park Brake - With the brake (pedals) properly adjusted (but not actuated), adjust clevis of the park brake linkage so there is 2 clicks of free play in the linkage. The park brake lever should begin to lock at 3 clicks of lever travel, and the brakes should be fully locked at 6-8 clicks.

JD 3120, 3320, 3520, 3720 Tractor With Cab - Lift both rear wheels several inches off the ground. Place a visible white horizontal line on the wheels or hubs to observe wheel RPM during setup. If the two rear transmission brake bell crank springs are attached to the ROPS, proceed to the next step. If not, install missing spring(s). Rotate lever clockwise to unlock brake pedal latch. Push/pull on the pedal foot pad to make sure they are traveling at an equal distance, about 40 mm (1-37/64 in.) from the starting point. If both pedals are traveling an equal distance, then proceed to the next step. If not, adjustment is necessary: To adjust lift pedal linkage, loosen both jam nuts away from the turnbuckle. Turn turnbuckle clockwise to increase pedal travel distance, and counterclockwise to decrease pedal travel distance. Adjust pedal linkage on opposite side, so both pedals travel the same distance of approximately 40 mm (1-37/64 in.) from the starting point. Lock the pedals together. Start the tractor, place the transmission in B-2 position, and set the engine throttle speed to 2000 RPM. Press down on brake pedals. Both wheel hubs should slow down at the same time (or similar) rate of speed. If not, adjust turnbuckles until they slow down at about the same rate of speed. Tighten both jam nuts against the turnbuckles adjusted. Lower tractor.

Using Brake Pedals (John Deere 3120, 3320, 3520, 3720 tractor with PowrReverser)

Using Brake Pedals As Driving Brake: Lock pedals together when not using the turn brakes or for road travel or transport. Slow down before making a turn. Rotate brake pedal latch clockwise until it locks into right turn brake pedal. Depress either brake pedal to slow or stop the machine. With latch down, brakes should stop machine in a straight line. Using Brake Pedals to Assist In Turning: Do not apply turn brakes while an implement is engaged with the ground. Damage to the 3-point hitch and implement may occur. Turn brake pedals can be used to make tighter turns and may reduce unnecessary backing. Rotate brake pedal latch counterclockwise until it stops against left turn brake pedal. The brake pedals will now function independently. To make a tighter left turn, depress left turn brake pedal while turning to the left. To make a tighter right turn, depress right turn brake pedal while turning to the right.

Using Brake Pedals (John Deere 3120, 3320, 3520, 3720 tractor with eHydro)

Rotate brake pedal latch counterclockwise until it locks into left turn brake pedal. Depress either brake pedal to slow or stop the machine. With latch down, brakes should stop machine in a straight line. Using Brake Pedals to Assist In Turning: Do not apply turn brakes while an implement is engaged with the ground. Damage to the 3-point hitch and implement may occur. Turn brake pedals can be used to make tighter turns and may reduce unnecessary backing. Rotate brake pedal latch clockwise until it stops against right turn brake pedal. The brake pedals will now function independently. To make a tighter left turn, depress left turn brake pedal while turning to the left. To make a tighter right turn, depress right turn brake pedal while turning to the right.

Locking Park Brake

Lock both brake pedals together using brake pedal latch. Press down on brake pedals with foot. John Deere 3120, 3320, 3520, 3720 Tractors without Cabs: Pull park brake lever up to the locked position. Park brake light should illuminate. Tractors with Cabs: Pull park brake knob out to the locked position. Park brake light should illuminate. Remove foot from brake pedals. Unlocking Park Brake - Press down on brake pedals with foot. Tractors without Cabs: Pull up slightly on park brake lever while depressing the release button. Push park brake lever down to the unlocked position. Park brake light should be off. JD 3120, 3320, 3520, 3720 Tractors with Cabs: Push park brake knob in to the unlocked position. Park brake light should be off. Remove foot from brake pedals. Both pedals should now be released from the locked position.

John Deere 3120, 3320, 3520, 3720 Tractor Wheels

Adjusting Tilt Steering Wheel

Stop the machine before adjusting the steering wheel. Lock the steering wheel in position before driving the machine. Stop machine. Pull tilt steering control lever up to release steering wheel. Adjust steering wheel to desired position. Release tilt steering control lever to lock steering wheel in position. Using Differential Lock (Traction Assist) - Engaging Differential Lock - Stop or slow machine movement. Differential lock will remain engaged as long as rear wheel slippage occurs. If tires slip and regain traction repeatedly, hold down pedal with foot so differential lock remains engaged. Push down on differential lock pedal to engage differential lock. Disengaging Differential Lock - Remove foot from differential lock pedal. Rear wheel slippage will keep differential lock engaged. Lock will automatically disengage when traction equalizes. If lock does not disengage when foot is removed from pedal, depress one turn brake pedal and then the other.

John Deere 3120, 3320, 3520, 3720 - Mechanical Front Wheel Drive (MFWD)

JD 3120, 3320, 3520, 3720 mechanical front wheel drive (MFWD) enables the powertrain to drive both front and rear axles for improved traction on difficult ground conditions and provides 4-wheel braking. MFWD can be engaged and disengaged on-the-go with light loads and on low traction surfaces. To improve braking on sloped, icy, wet, or graveled surfaces, engage the MFWD. Add ballast to the tractor and travel at a reduced speed to avoid skidding and loss of steering control. Always disengage MFWD when driving on a paved surface. Put the transmission levers in neutral to move the machine when the engine is not running. Pull up on MFWD lever to engage MFWD. Instrument panel MFWD light will illuminate when MFWD is activated. It may be necessary to reduce engine load to disengage front wheel drive. Push down MFWD lever to disengage MFWD. Tips for Operating MFWD: Maintain front tire pressure at maximum allowable level to ensure proper tire performance in all field conditions. Engage MFWD to provide four-wheel braking. Disengage MFWD when driving machine to or from work site to increase front tire life.

John Deere 3120, 3320, 3520, 3720 Tractor - Removing and Installing Wheels

Front Wheel Removal - Loosen lug nuts slightly before raising front axle. Raise front of machine and lower onto support stands so that machine is supported by front axle. Remove lug bolts and wheel. If the front wheels are being removed to perform work on the front axles, lower machine onto suitable stands that will support the machine by the frame. Front Wheel Installation - Install wheels onto axle, insert lug bolts and lightly tighten bolts. Raise front of machine, remove support stands and lower machine to floor. Tighten lug bolts to 140 Nm (103 lb-ft). Rear Wheel Removal - Loosen lug bolts slightly before raising machine rear axle. Raise rear of machine and lower onto support stands so that machine is supported by rear axle. Remove lug bolts and wheel. Rear Wheel Installation - Install wheels onto axle, insert lug bolts and lightly tighten bolts. Raise rear of machine, remove support stands and lower machine to floor. Tighten lug bolts to 140 Nm (103 lb-ft).

Selecting Front Tire Rolling Direction

John Deere 3120, 3320, 3520, 3720 Tractors equipped with directional type tires (such as bar tires) have directional arrows located on the tire sidewall. Under most conditions, tires should be installed with the directional arrow pointing in the direction of travel. If machine is mainly used for loader operations, lug direction may be reversed to increase tire life and improve traction while backing out of dirt piles. Move wheel from one side of machine to the other to change tire rolling direction.

Changing Wheel Spacing and Tread Width

The front and rear wheels can be mounted in wide or narrow positions to increase or decrease wheel spacing. To provide best stability, operate machine with rear wheels mounted in the wide tread position whenever possible. Front Wheel Positions: Wide position - Install wheel with valve stem to the inside. Narrow position - Install wheel with valve stem to the outside. Rear Wheel Positions: Wide position - Install wheel with valve stem to the inside. Narrow position - Install wheel with valve stem to the outside. For 8 position wheels, the mounting flanges on the rear rims are closer to one edge of the rim than the other, allowing the inner wheels to be mounted in different positions. By changing this position of the wheel on the rim, up to eight different tread widths can be achieved on some machines. Various positions cannot be used because the tires would strike the fenders. Certain other positions may result in equal tread widths. Tread width is measured from centerline-to-centerline of each tire. Rear Tire Size: 14.00-20 R3 / 16.00-20 R4 / 11.2-24 R1. Front Tire Size: 8.5-15 R4 / 7.00-14 R1 / 8.5-14 R4.