HH45 Harvester Head, HH55 Harvester Head, HH65 Harvester Head and HH75 Harvester Head Caterpillar

Changing Oil in the Tensioner

The oil should be changed whenever the lock pin is repaired or replaced.

The oil is contained in the housing of the tensioner. The oil is under pressure from a gas spring. The oil presses outward onto a working piston. The working piston presses onto the saw bar holder. This pressure on the attachment keeps a constant tension on the saw chain.

Note: A tool kit was shipped with the harvester head. A plastic elbow assembly is in this kit. This elbow assembly is needed for this procedure.

1. Remove the saw chain.

   Reference: Refer to Operation and Maintenance Manual, "Saw Chain-Remove/Install".

2. Relieve the pressure on the gas spring.

   1. Clean any dirt from the housing. Be sure that the control valve is in the operating position. The lower bar guide axle is equipped with a tapped hole. Remove any dirt from the tapped hole.
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   Illustration 1	g00604401
   The tensioner is shown with the plastic elbow. (1) Control valve is shown in the operating position. (2) Housing. (3) Plastic elbow. (4) Bolt. (5) Nut. (6) Lock screw. (7) Mark on Plastic Elbow.

   Note: The plastic elbow (3), bolt (4), and the nut (5) are shipped with the Harvester head. These parts are needed in order to relieve the pressure on the gas spring.

   2. Install the plastic elbow (3) onto the saw bar tensioner. The plastic elbow should be installed on the bar guide axle that is farthest away from the control valve (1). The gas piston should be covered when the plastic elbow is installed.

   3. Install bolt (4) through the plastic elbow (3). Install the bolt into the tapped hole of the bar guide axle.

      Note: The nut (5) may need to be positioned close to the head of the bolt. This will allow the bolt to be fully installed into the bar guide axle.

   4. Turn the nut (5) until contact is made with the plastic elbow (3). The plastic elbow should be against the housing.

   5. Remove locking screw (6) from the housing. Use the allen wrench that is supplied in the tool kit in order to remove the locking screw. Turn nut (5) counterclockwise. Make sure that the bolt (4) does not turn when nut (5) is backed off. This will allow the gas piston to move out of the housing.

      Note: Do not allow the mark (7) that is on the plastic elbow to move past the edge of the housing.

   6. The pressure in the gas spring is now relieved.

3. Remove the four allen head screws that retain the control valve. Pull the control valve 10 mm (0.4 inch) from the housing. Clean any dirt from the control valve. Press the working piston inward and remove the control valve.

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Illustration 2	g00379812

4. Remove the plastic elbow that was used for relieving the gas spring pressure. Press the working piston and the gas spring inward. This will expel most of the oil.

5. Slowly pull the working piston from the housing. The end of the working piston is tapped. An M4 bolt can be threaded into this tapped hole in order to pull the working piston. Add new oil through the hole for the control valve as you pull out the working piston.

6. Plug the hole for the control valve. Push in on the working piston. The gas spring will be expelled slightly.

7. Slowly pull the working piston from the housing. Pull out the working piston as you are adding new oil.

8. Plug the hole for the control valve. Press the working piston inward. The gas piston will be expelled.

9. Repeat steps 4 through 6 one time. This will expel as much of the oil as possible.

Filling the Tensioner With Oil

Illustration 3	g00380099
(1) Tensioner. (2) Plastic elbow. (3) Line on plastic elbow.

1. Install the plastic elbow (2) onto the bar guide axle. Be sure that the mark (3) that is on the plastic elbow is in line with the end of the housing.

2. The control valve for the tensioner should be installed in the operating position. The operating position for the control valve is closed.

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Illustration 4	g00603422
Access hole for the filler plug

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Illustration 5	g00622149

3. Place the harvester head into the horizontal position.

4. Shut off the engine.

5. Position the tensioner so that the oil filler plug is in the highest position. This is accomplished by rotating the tensioner into a horizontal position. The bar guide axles should now be parallel to the ground. The oil filler plug is located on the housing on the opposite side of the gas piston. The oil filler plug is a 4mm allen head screw.

6. Install the plastic elbow. The line on the plastic elbow should still be at the edge of the housing.

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Illustration 6	g00622153
The End View of the Tensioner is Shown. (A) Cam is shown in the original position. (B) Cam is moved away from the oil filler plug. (1) Tensioner. (8) Cam. (4) Oil Filler Plug. (6) Allen Head Screw. (7) Tapped Hole.

7. The cam (8) for the lubricating oil pump is covering part of oil filler plug (4). This cam must be moved in order to remove oil filler plug (4). Remove allen head screw (6) from tensioner (1). Gently move cam (8) so that oil filler plug (4) is exposed. Replace allen head screw (6) into tapped hole (7) when the cam is moved. This will hold the cam away from the oil filler plug so that the oil filler plug can be removed.

8. Use the supplied allen wrench in order to remove the oil filler plug. The oil is added by using a syringe. Withdraw the oil from the bottle by using the syringe.

   Note: The syringe and the bottle of oil is supplied with the Harvester Head.

9. Wait until no air bubbles are present. Force the oil into the filler plug opening by using the tip of the syringe. Fill the tensioner with oil until the gas spring is expelled. Fill with oil until the gas spring is pressed against the plastic elbow.

10. Install the O-ring and the filler plug. Press on the plastic elbow. If the gas spring can easily be depressed, air is present. Purge the air. Use the plug that is located on the housing in order to purge the air. This plug is located in front of the control valve. Refill the tensioner with oil. Press on the plastic elbow again. The plastic elbow should not move easily. The tensioner is now full of oil.

11. Remove allen head screw (6). Move cam (8) back into the original position. Install allen head screw (6) into tapped hole (7) .

12. Set the gas spring.

13. Install the saw bar and test the tensioner for proper operation.

    Reference: Refer to Operation and Maintenance Manual, "Saw Bar Tensioner-Inspect" for more information on testing the saw bar tensioner.

Setting the Gas Spring

1. Set the gas spring.
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   Illustration 7	g00604401
   (1) Control valve is shown in the operating position. (2) Housing. (3) Plastic elbow. (4) Bolt. (5) Nut. (6) Lock screw. (7) Mark on Plastic Elbow.

   1. The mark (7) on the plastic elbow should be against the housing (2) .

   2. Turn nut (5) clockwise in order to press the gas spring inward. Press the gas spring inward until the plastic elbow is touching the housing.

   3. When the plastic elbow is touching the housing, install the lock screw (6). The gas spring is now set.