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| Illustration 1 | g00751212 |
(1) Saw bar tensioner. (2) Tension control valve (operating position). (3) Bar Guide Axles. (4) Lock pin. (5) Working Piston. (6) Saw bar holder. | |
Lock pin (4) slides in a groove. The groove is cut into saw bar holder (6). The groove must be kept free of defects and in good condition. The width of the groove (A) must be 5 mm (0.2 inch) wide. The end of the groove (B) must be .5 mm (0.02 inch) from the edge of the attachment for the saw bar. See illustration 1. Repair the groove, if necessary. Any defects in the groove must be welded. The groove should be filed to the original dimensions.
| NOTICE |
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Welding processes that develop very high temperatures may cause deformation of the saw bar attachment. |
If lock pin (4) has not extended out of saw bar tensioner (1), check for binding. The lock pin may be trapped in the hole for the lock pin. The hole for the lock pin is located in the housing of saw bar tensioner (1) .
Use the following procedures in order to expel the lock pin.
- Place control valve (2) into the operating position. This should cause working piston (5) to move to the forward position.
- Use a rubber mallet in order to tap working piston (5) toward saw bar tensioner (1). This will cause the lock pin to be forced out of the housing.
- Gently tap the sides of lock pin (4). This will push any burrs out of the way.
- Move control valve (2) into the open position. Push working piston (5) inward in order to place control valve (2) in the locked position.
- Push lock pin (4) back into the hole in the housing by using a round punch. The edges of the hole can now be deburred.
- Move control valve (2) back to the operating position. Use a rubber mallet in order to tap working piston (5) toward saw bar tensioner (1). This will cause the lock pin to be forced out of the housing. If lock pin (4) is functioning properly, the lock pin should now extend out of the housing.
- If lock pin (4) has not extended out of the housing, a problem still exists.
Note: Ensure that saw bar tensioner (1) is full of oil and ensure that no air is in the oil of saw bar tensioner (1). Ensure that the tensioner is functioning properly. If the saw bar tensioner is not full of oil, the lock pin may not be expelled. Refer to Operation and Maintenance Manual, "Saw Bar Tensioner Oil - Change" for information on adding oil.
If the problem still persists, lock pin (4) will need to be repaired or replaced. The hole for the lock pin may need to be reamed.
Disassembly of the Lock
The lock pin is covered by a plug and an O-ring.
Plug Removal
- Remove the pressure that is on the gas spring.
Reference: Refer to Operation and Maintenance Manual, "Saw Bar Tensioner Oil - Change" for information on relieving the pressure of the gas spring.
- Remove the plug (7). Push lock pin (4) out of the housing from below using a long punch.
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| Illustration 2 | g00751335 |
(4) Lock Pin. (5) Working Piston. (7) Plug. (8) Sleeve. | |
- Remove sleeve (8) by using long narrow pliers. Sleeve (8) is located under lock pin (4) .
- If necessary, ream the hole. Use a 4 mm (0.158 inch) reamer. Chamfer the bottom edge of the hole.
- Remove any shavings from the hole. Check for correct operation of lock pin (4) .
- If lock pin (4) will not move, the pin may be bent. Replace the pin.
- Apply grease to sleeve (8). Place sleeve (8) on lock pin (4). Install sleeve (8). The sealing lip should be facing the larger end of lock pin (4) .
- Install lock pin (4) and install sleeve (8) into the housing of saw bar tensioner (1). Install plug (7). Apply pressure to working piston (5). This will force oil into the hole of the lock pin. Lock pin (8) should be forced into the groove of the saw bar holder.
- Refill the tensioner with oil and purge the air from the tensioner. See Operation and Maintenance Manual, "Saw Bar Tensioner Oil - Change".