Specifications, Service and Repair of Farm and Lawn Tractors

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John Deere 3120 Tractor Specs Overview

John Deere 3120 Tractor Engine

Model - Yanmar 3TNV84
Type - Diesel
Gross Horsepower - 22 kW (29.5 hp)
Low Idle Speed - 950 rpm
Rated Engine Speed - 2600 rpm
High Idle Speed - 2775 rpm
Operating Range - 1000 - 2810 rpm
Engine Torque/Rated Speed (3120) - 75.4 Nm (55.6 lb-ft)
Maximum Torque/1560 rpm (3120) - 90.4 Nm (66.7 lb-ft)
Displacement - 1.5 L (91.5 cu in.)
Cylinders - 3
Bore and Stroke - 84 x 90 mm (3.3 x 3.54 in.)
Compression Ratio - 18.5:1

Lubrication Pressurized

Cooling System - Water Pump
Oil Filter - Single Element
Air Cleaner - Dry Type with Safety Element
Starting Aid - Air Heater

Electrical System

Type - 12 Volt
Battery - Size 500 Cold Cranking Amps at -18°C (0°F)
Alternator - 40 Amp
Starter Size - 1.4 kW (1.9 hp)

Fuel System

Fuel Filter - Replaceable Element
Fuel - Diesel
Fuel Pump - In-Line with Electric Shutoff
Fuel Delivery - Direct Injection, Self Bleeding

JD 3120 Tractor Drive Train

Transmission - 12x12 PowrReverser (4WD Only)
Number Of Speeds - 12 Forward, 12 Reverse
Transmission - eHydro (4WD Only)
Number Of Speeds - Infinite Forward, Infinite Reverse
Mechanical Front Wheel Drive - Standard All Models
Capability for MFWD - All Ranges
Rear Final Drive Type - Spur Gear
Differential Lock - Mechanical
Brakes Type - Wet Disk
Steering - Power, Hydrostatic
Main Clutch Disk Type - Multiple Stage Wet
Main Clutch Disk Diameter (PowrReverser Transmissions) - 11.3 cm (4.4 in.)
Front Axle Operating Capacity - 720-1450 kg (1587-3197 lb)
Rear Axle Operating Capacity - 1815 kg (4002 lb)
Drawbar Tongue Capacity - 400 kg (882 lb)

John Deere 3120 Tractor Hydraulic System

Type of System - Open Center
Power Steering - Standard
Implement and Steering Pump Type - Dual Tandem Gear Pump
Working Pressure - 17237 kPa (2500 psi)
Pump Capacity (Main) / Rated Speed - 32.5 L/min (8.6 gpm)
Pump Capacity (Power Steering) / Rated Speed - 20 L/min (5.3 gpm)
Total Flow of Pumps / Rated Speed - 52.5 L/min (13.9 gpm)

3 Point Hitch

Type - Category 1
Lift Capacity (24-in. behind link arms) - 999 kg (2200 lb)
Dimension - Lower Link Ball Socket ID - 22 mm (7/8 in.)
Dimension - Upper Link Pin Hole ID - 19 mm (3/4 in.)
Dimension - Normal Width/Lower Hitch Pins - 68.6 cm (27 in.)
Dimension - Normal Height From Center Pin to Hitch Pin - 45.7 cm (18 in.)

Drawbar Load

Maximum Static Vertical Load - 255 kg (562 lbs)

John Deere 3120 Tractor PTO

Type - Independent
Clutch Type - Wet Disk
Brake Type - Wet Disk
Speed (Mid PTO rpm/Rated Engine Speed) - 2100 rpm
Speed (Rear PTO rpm/Rated Engine Speed) - 540 rpm

Fluid Capacities

Fuel Tank (tractor without cab) - 51.1 L (13.5 gal)
Fuel Tank (tractor with cab) - 44 L (11.8 gal)
Cooling System (tractor without cab) - 5.3 L (1.4 gal.)
Cooling System (tractor with cab) - 7.0 L (1.8 gal.)
Crankcase w/ Filter (3120, 3320, 3520) - 4.8 L (5.1 qt.)
Crankcase w/ Filter (3720) - 5.7 L (6.0 qt.)
Transmission and Hydraulic System (PowrReverser Models) - 23.8 L (6.3 gal.)
Transmission and Hydraulic System (eHydro Models) - 25.7 L (6.8 gal.)
Front Axle - 4.5 L (1.2 gal.)
Windshield Washer Fluid Reservoir - 2.8 L (0.7 gal.)
Refrigerant (R134a) - 1.3 kg (2.8 lb)

Wheels

Front Tires - 7.00-14 6PR R1 GA / 83 kPa/250 kPa (12 psi/36 psi)
Rear Tires - 11.2-24 6PR R1 GA / 83 kPa/180 kPa (12 psi/26 psi)

JD 3120 Tractor Dimensions

Wheelbase - 1.7 m (68 in.)

Height From Ground (Tractor without cab, with standard R1 tires)

- To Top of Hood - 1.4 m (57 in.)
- To Top of Folding ROPS - 2.4 m (93.3 in.)

Height From Ground (Tractor with Cab, R3 tires)

- To Top of Cab - 2.3 m (89.4 in.)

Weight:

- Models without cab - 1316 kg (2900 lb)
- Models with cab - 1619 kg (3570 lb)

Servicing Engine System

Draining John Deere 3120 Tractor Engine Cooling System

- Park machine safely.

- Allow engine to cool.

- Raise hood.

- Slowly open radiator cap to the first stop to release all pressure.

- Close radiator cap tightly.

- Position drain pan under radiator petcock on left side of machine.

- Open petcock and drain coolant.

- Disconnect coolant hose at connection to oil filter base, and allow all coolant to drain into pan.

- After coolant drains from the recovery tank, remove radiator cap.

- Close radiator petcock and connect coolant hose.

- Flush cooling system.

Flushing JD 3120 Tractor Cooling System

- Fill cooling system with clean water. Follow directions on container.

- Install and tighten radiator cap.

- Start and run engine until it reaches operating temperature.

- Stop engine.

- Open radiator petcock and disconnect coolant hose.

- Drain cooling system immediately before rust and dirt settle.

- Close radiator petcock and connect coolant hose.

Cleaning Fuel Filter Sediment Bowl and Replacing Filter

- Allow John Deere 3120 Tractor engine to cool.

- Raise hood.

- Close fuel shut-off valve.

- Position drain pan under fuel filter sediment bowl to catch fuel spillage.

- Turn locking collar counterclockwise to remove bowl.

- Remove and discard the fuel filter.

- Remove and retain the plastic ring and spring from sediment bowl.

- Clean bowl, plastic ring, and spring.

- Install plastic ring and spring in original position in sediment bowl.

- Install new filter to filter head.

- Place sediment bowl and locking collar in position.

- Tighten locking collar to filter head to secure.

- Open fuel shut-off valve.

- Lower hood.

- Fuel system is self bleeding.

- Crank engine to bleed fuel system.

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.

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