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Service Transmission

Transmission and Hydraulic Oil

IMPORTANT: Avoid damage! Machine is filled with John Deere HY-GARD™ (J20C) Transmission/Hydraulic Oil at the factory. DO NOT mix oils. DO NOT use type “F” automatic transmission fluid


Use oil viscosity based on the expected air temperature range during the period between oil changes.

John Deere J20C HY-GARD Transmission/Hydraulic Oil is recommended.

Use John Deere BIO HY-GARD™ oil when a biodegradable fluid is required.

Biodegradable Oil


IMPORTANT: Avoid damage! Biodegradable oils, other than BIO HY-GARD™, are not recommended.

When use of a biodegradable lubricant is desired or required, BIO HY-GARD is recommended. BIO HY-GARD may be used under normal mowing conditions.

DO NOT USE biodegradable lubricants in machines for the following operations:

• Any machine used for scalping procedure.

• Any verticut operation in temperatures exceeding 32°C (90°F).

• Mixing of biodegradable oil and mineral oil will reduce the biodegradability of the lubricant in the machine. Mixing of HY-GARD and BIO HY-GARD will not result in performance deterioration.

Cold Weather Operation

Precautions should be taken if BIO HY-GARD containers or equipment are stored for long periods of time in extremely cold temperatures. Freezing should be expected if BIO HY-GARD is subjected to the following temperatures:

• Stored for six months at -18° to -23°C (-1° to -10°F)

• Stored for seven days at -23° to -26°C (-10° to -15°F)

• Stored for three days at -26° to -29°C (-15° to -20°F)

• Stored for two days at -29° to -34°C (-20° to -30°F)

• Stored for one day at -34°C (-30°F) and below.

IMPORTANT: Avoid damage! Equipment should not be started or any operation attempted until BIO HY-GARD™ has reached a safe operating viscosity.

If freezing of BIO HY-GARD is suspected, the container or equipment MUST be warmed to at least 0°C (32°F) and maintained for 24-48 hours to ensure the fluid has reached a safe operating viscosity.

Converting From HY-GARD to BIO HY-GARD

Systems being converted from HY-GARD to BIO HY-GARD should follow the procedure listed below to obtain maximum lubricant biodegradability.

1. Park machine on a level surface.

2. Lower cutting units, stop engine, set park brake and remove key from ignition.

3. Drain hydraulic reservoir.

4. Replace hydraulic filter.

5. Fill reservoir with BIO HY-GARD to appropriate level.

6. Start engine and bring to medium idle.

7. Turn steering wheel full stroke several times and cycle cutting units several times.

8. Stop engine and check hydraulic oil level. Add BIO HY-GARD to appropriate level.

9. Operate machine under normal operating conditions for a minimum of two hours.

10. Repeat steps 1-8.

11. Follow recommended maintenance schedules.

Checking Transmission Drive Oil Level

1. Park machine safely. (See Parking Safely in the SAFETY section.)


2. Check fluid level in expansion tank (B). If there is hydraulic oil in the expansion tank, there is no need to check level at the fill port.

3. If hydraulic oil is not present in the expansion tank, remove fill plug (A). Hydraulic oil level should be to the bottom of the fill port when hydraulic oil is cold.

4. Install fill port plug. Tighten to 27 •m (20

5. Check to ensure fluid is present in expansion tank (B) when hydraulic oil is cold.

6. Fluid level in expansion tank should be approximately 25 mm (1 in.) when hydraulic oil is cold.

Changing Transmission Oil and Filter

c CAUTION: Avoid injury! Escaping fluid under high pressure can penetrate the skin and cause serious injury. Avoid the hazard by relieving pressure before connecting hydraulic or other lines. Tighten all connections before applying pressure.

• Search for leaks with a piece of cardboard. Protect hands and body from high-pressure fluids.

• If an accident occurs, see a doctor immediately. Any fluid injected into the skin must be surgically removed within a few hours or gangrene may result. Doctors unfamiliar with this type of injury should reference a knowledgeable medical source. Such information is available from Deere & Company Medical Department in Moline, Illinois, U.S.A. In the United States and Canada only, this information may be obtained by calling 1-800-822-8262.

IMPORTANT: Avoid damage! Contamination of hydraulic fluid could cause transmission damage or failure. Do not open oil reservoir cap unless absolutely necessary.

Severe or unusual conditions may require a more frequent service interval.

NOTE: Use ONLY John Deere HY-GARD™ (J20C) Transmission-Hydraulic Oil.

1. Park machine safely. (See Parking Safely in the SAFETY section.)


2. Loosen hose clamp (A) at reservoir and hose clamp at suction strainer. Carefully remove hydraulic suction hose between the bottom of the reservoir and the suction strainer.

3. Drain oil into a drain pan with at least a 37.8 L (10.0 gal) capacity.


4. Turn hydraulic oil filter (B) to the left (counterclockwise) to remove. Use drain pan to catch dripping oil. Verify that oil filter O-ring gasket does not stick to the filter base.

• Put a film of clean oil on seal of new filter.

• Tighten filter until it contacts mounting surface.

• Tighten filter one full turn after gasket contact. A filter wrench may be required.

5. Install suction hose and tighten hose clamps.

6. Fill reservoir with approximately 37.8 L (10.0 gal) of oil. Use John Deere HY-GARD™ oil or an equivalent oil meeting John Deere specifications.


• Remove fill plug (C).

• Remove fill cap (D) from secondary hydraulic tank.


• Remove plug (E) in T-fitting to allow air to vent out.

• Fill main hydraulic reservoir to 100% capacity.

• Fill expansion tank at least until you have 1 inch of fluid in tank.

• Install fill port plug. Tighten to 27 •m (20 lb-ft).

• Install plug in T-fitting.

7. Start the engine. Cycle hydraulic controls and turn steering wheel back and forth for approximately 5 minutes.

8. Stop the engine and check oil level in expansion tank and for leaks. Add oil as needed to expansion tank.

Changing Hydraulic Oil Strainer

c CAUTION: Avoid injury! Touching hot surfaces can burn skin. The engine, components, and fluids will be hot if the engine has been running. Allow the engine to cool before servicing or working near the engine and components.

1. Change hydraulic oil and filter.


2. Locate suction strainer (A) under left side of machine.

3. Loosen adjustable hose clamps (B).

NOTE: Use drain pan to catch dripping oil.

4. Loosen and remove suction strainer from hydraulic suction hose.

5. Wipe excess oil from hoses and check for wear. Replace if necessary.

6. Check hose clamps and replace if necessary.

7. Install new suction strainer and tighten hose clamps.

NOTE: Ensure that arrow on suction strainer is pointing toward the front of the machine.

8. Check hydraulic oil level and replace any lost fluid using John Deere HY-GARD™ oil or equivalent oil meeting John Deere specifications.

Checking Mow Speed

NOTE: This machine should never travel faster than 9.6 km/h (6 mph) when the Mow/ Transport lever is in the Mow position . Use the chart and procedure below to determine the machine’s mow speed and adjust as necessary.

Elapsed Time


12 sec

9.6 km/h (6.0 mph)

13.5 sec

7.2 km/h (4.5 mph)

15 sec

6.4 km/h (4.0 mph)

17.5 sec

5.6 km/h (3.5 mph)

20 sec

4.8 km/h (3.0 mph)

1. Measure a distance of 26.8 m (88 ft) and mark the start and end points.

2. Move the Mow / Transport lever to the Mow position, but do not lower the cutting units to the ground.

NOTE: Make sure engine is running at full throttle.

3. Drive machine forward so that it is traveling at the full mow speed and in a straight line between the start and end points.

4. Make three passes, recording the time required to travel the measured distance, and calculate the average time for the three passes.

5. Adjust the mow speed as necessary.

Adjusting Transmission Neutral Switch

NOTE: The machine may creep forward or backward while in neutral position with engine running. If so, an adjustment is needed.

c CAUTION: Avoid injury! Do not attempt this adjustment unless you are a qualified and properly trained technician. Improper adjustment can result in an unsafe machine.

1. Park machine on a level surface.

2. Lock the park brake.

c CAUTION: Avoid injury! The machine can fall or slip from an unsafe lifting device or supports.

• Use a safe lifting device rated for the load to be lifted.

• Lower machine onto jackstands or other stable supports and block wheels before servicing.

3. Lift machine with a suitable lifting device just high enough to allow drive wheels to turn.

4. Support machine with stable supports.

5. Operate lift control and allow cutting units to settle on the ground.

6. Before making any adjustment, perform a thorough visual inspection of linkages and return springs for damage. Repair or replace as necessary.


7. Loosen the nut on the external neutral centering mechanism pivot bolt (A).

8. Loosen nut (B) on the hydrostatic pump neutral center adjustment screw (C).

9. Turn the hydrostatic pump neutral adjustment screw until the wheels do not turn.

10. Tighten the nut on the hydrostatic pump neutral center adjustment screw.

11. Tighten the nut on the external neutral centering mechanism pivot bolt.

12. Verify that wheels do not creep.


13. Adjust neutral switch (D) if necessary.

• With both forward and reverse pedals in the neutral position, check to ensure that hex head bolt (E) is positioned at the upper portion, or target zone, of the switch.

14. If switch face target zone does not line up with hex head bolt (E), loosen flange head bolts (F) and reposition.

15. Hex head bolt (E) should be adjusted to be 3 (.12

c CAUTION: Avoid injury! Engine exhaust fumes contain carbon monoxide and can cause serious illness or death.

Move the machine to an outside area before running the engine.

Do not run an engine in an enclosed area without adequate ventilation.

• Connect a pipe extension to the engine exhaust pipe to direct the exhaust fumes out of the area.

• Allow fresh outside air into the work area to clear the exhaust fumes out.

16. Start engine and run at slow idle.

c CAUTION: Avoid injury! Use extreme caution when adjusting for neutral creep. Drive wheels are free to spin when machine is raised off the floor and the engine is started.

Do not have engine running any longer than necessary to do adjustment. Shut off engine and remove key as soon as possible after adjustment is made.

17. With an operator in the operator seat, disengage the park brake.

18. Have the operator depress the drive pedals in both directions and release.

19. Drive wheels should stop turning when pedals are released. If not, repeat adjustment.

20. Adjust reverse pedal linkage until reverse pedal is approximately 40 mm (1.6 in.) lower than the forward pedal.

21. Verify that when park brake is set, the engine shuts down when forward/reverse pedals are moved.

Adjusting Mow Speed

c CAUTION: Avoid injury! Operating this machine at an excessive speed can cause loss of control and rollover accidents.

Never adjust the mow speed higher than the factory specification.

1. Park machine safely. (See Parking Safely in the SAFETY section.)


2. Loosen jam nut (A) and adjust hex head bolt (B) to reduce or increase mow speed. Keep the speed within the recommended range.

• Lengthening the bolt reduces mow speed.

• Shortening the bolt increases mow speed.

3. Tighten jam nut after mow speed adjustment has been made.

4. Check the mow speed.

Adjusting Mow-Transport Cable

1. Park machine safely. (See Parking Safely in the SAFETY section.)


2. Loosen hex socket head bolt (A) until mow-transport cable (B) can be repositioned under cable clamp (C).


3. Move mow stop shaft (D) as far to the right as possible so that vertical bolt bottoms in slot. Spacer (E) will be close but not necessarily touching the face of the switch (F).

4. Exercise the mow-transport lever and verify that the vertical bolt bottoms out in the slot when lever is in the mow position.

5. Reposition cable clamp and tighten hex socket head bolt.