Specifications, Service and Repair of Farm and Lawn Tractors


John Deere 3720 Tractor Specs Overview

John Deere 3720 Tractor Engine

Engine Model - Yanmar 3TNV84HT
Cylinders - 3
Displacement, cu in (L) - 91.5 (1.496)
Engine Bore, in (mm) - 3.3 (84)
Engine Stroke, in (mm) - 3.54 (90)
Block Design, Replaceable Liners - Cast in block
Aspiration, Turbocharged or Naturally Aspirated - Turbocharged
Engine Power, Rated, hp (kW) - 43.7 (32.6)
Engine Speed, rpm - 2600
Power Boost, hp (kW) - No boost
Fuel Tank, gal (L) - 13.5 (51.1)
Fuel System Description - Rotary-Distributor Type
Fuel System Control - Mechanical
Fuel Injection to combustion chamber - Direct
Exhaust Pipe - Underhood std; vertical opt
Fan Drive Type - Belt
System Rating, Volts - 12
Alternator Rating, Amps - 40

John Deere 3720 Tractor Transmission

Description - eHydro
Transmission Type - 3 Range Hydrostatic
Forward / Reverse Speeds - Infinite, 3 range
Maximum Speed Forward, mph (kph) - 19 (30.6)
Creeper Range - Yes, hydrostatic
Shuttle (Forward-Reverse) - Yes

John Deere 3720 Tractor PTO (Power take off)

PTO Horsepower, hp (kW) - 35 (26.1)
PTO Speeds, rpm - 540
PTO operational Type - Independent


Drive Wheels - 4WD
Tractor Steering Configuration - Front Steer

JD 3720 Tractor Rear Axle

Final Drive - Spur gear
Axle Output End - Flange
Axle Bar Diameter, in (mm) - No bar axle


Brake Type - Wet disc

John Deere 3720 Tractor Hydraulic System

Hydraulic System Type - Open center
Standard Pump Flow, gpm (Lpm) - 13.9 (52.5)
Standard Remote Valves - 5

3-Point Hitch Features

3-Point Hitch Category - Category 1
Draft Sensing or Lift Control - Position Control
Draft Link Ends Adjustable - Optional

3-Point Hitch Lift Capacity

Standard Lift Capacity 24 Inches behind pin, lb (kg) - 2,220 (999)


Drawbar Description - Adjustable length


Wheelbase, 4WD, in (mm) - 68 (1727)

Tire Size

Front Tire Size, 4WD - 7.0-14 / 6PR R1
Rear Tire Size - 11.2-24 / 6PR / R1

Operating JD 3720 Tractor 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.

Choose a speed range to match work application:

- A – Low speed/high power operations such as tilling hard soil, mowing high grass or positioning backhoe.

- B – Operations including moderate tilling, hauling, and grass mowing.

- C – 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.

Testing John Deere 3720 Tractor 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.

- JD 3720 Tractor 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.

John Deere 3720 Tractor LoadMatch (eHydro)

LoadMatch enables the operator to prevent the engine stalling during heavy load applications such as operating with a loader. This feature is turned on and off using the display mode switch.

- Turn key switch to ON position.

- No error codes should be displayed.

- If any errors are displayed, activate the display mode switch to acknowledge the error.

- Press and hold the display mode switch until the display reads “RELEASE”.

- The last edited command will display, either Coast or Load.

- If Load is not displayed, use left or right turn signals to select the Load command.

- Activate the display mode switch to edit the LoadMatch setting.

- The LCD will display the last setting for LoadMatch, either On or Off.

- Activate the left or right turn signals to turn LoadMatch On or Off.

- When the desired setting is displayed, activate the display mode switch to store the setting.

- The LCD will flash the entered command twice and then change to the normal mode.

Reliable, three cylinder direct injection diesel engines provide maximum fuel efficiency and fast cold starts. Engines are available with or without power maximising Turbo chargers.

The JD 3720 Tractor features a turbocharged engine with intercooler for aggressive conditions.

Sophisticated hydraulic system. Instead of one single hydraulic pump that divides flow between steering and a hydraulic implement such as a loader, these units split the functions ensuring the steering always gets the oil it needs and the implement does, too.

No “robbing” of hydraulic power, that could threaten overall performance. High oil flow enabling quick operations – high pressure for high forces.

- Tilt steering wheel and seat adjust for your comfort.

- An exclusive digital Performance Tracking System instantly tells you the status of the vital systems on your tractor.

- Standard loader joystick stays close at hand and clear of your knee. Plus three hydraulic control valves are standard.

- Digital speedometer is perfect for precision tasks like spraying.

- Direct injection John Deere 3720 Tractor diesel engines are quick starting and offer deep reserves of torque for pulling heavy loads.

- Quick-Park loaders can be attached and detached in minutes – without tools.

- Standard 4WD digs in when doing loader work or heavy ground work. Greater durability with strong front and rear axles.

- Automotive style controls are instantly familiar.

- For more versatility, a front hitch and PTO is available – even engine driven for more versatility.