Power Fist 8052391 Manuel Du Propriétaire page 6

Maintenance
Caution:
• Use caution when working with the spring assembly. The spring is wrapped around, but not attached to, a
roller. If the spring is extended beyond its length, the end will come off the roller and the spring will roll up
with a snap, with a chance of pinching your hand. Also, the edges of the spring are very thin and can cut.
Care must also be taken to ensure no permanent kinks are put in the spring, as this will reduce the spring's
force.
• Do not use modified replacement parts or parts which will not give equivalent performance to the original
equipment.
Assembly procedure for seals:
When repairing a tool, make sure the internal parts are clean and lubricated. Coat each O-ring with O-ring
lubricant before assembling. Use a small amount of oil on all moving surfaces and pivots. After reassembly,
add a few drops of air tool oil through the air line fitting before testing.
Air supply pressure and volume:
Air volume is as important as air pressure. The air volume supplied to the tool may be inadequate because of
undersized fittings and hoses, or from the effects of dirt and water in the system. Restricted air flow will
prevent the tool from receiving an adequate volume of air, even though the pressure reading is high. The results
will be slow operation, misfeeds or reduced driving power. Before evaluating tool problems for these
symptoms, trace the air supply from the tool to the supply source for restrictive connectors, swivel fittings, low
points containing water, and anything else that would prevent full volume flow of air to the tool.
To replace piston:
1. Insert the flats on the lower end of the driver piston stem carefully into the end of a piston/plunger wrench.
2. Using another piston/plunger wrench, or another wrench of the proper size, unscrew the plunger from the
upper end of the stem. After this is done, it will be possible to lift the poppet off the stem
3. Place the piston/plunger wrench down over the piston stem onto the driver piston, locking the piston ears in
the slots in the wrench. Unscrew the piston from the stem.
To replace driver
1. It is not necessary to disassemble the piston-poppet-driver assembly to replace the driver. Pull the poppet up
on the driver piston stem as far as it will go.
2. Insert the piston/plunger wrench over the driver piston, locking the piston ears in the slots in the wrench.
Unscrew the piston from threaded portion of the stem.
3. To remove the driver blade from the piston stem, push the driver blade pin out of the stem. This will release
the blade.
4. Insert new driver blade into the slot in the end of the driver piston stem and assemble the driver blade pin.
Test the side play in the driver blade by grasping the driver piston stem in one hand and the blade in the
other, moving the blade sideways in alignment with the slot in case of any slight misalignment between the
blade and guide in the nose. If there is no side play, the blade should be removed and the top (pin end) just
barely dressed off with a stone. It is not necessary to do more than smooth off the top to get the necessary
side play. Do not grind. Reinsert the blade and pin in the stem and test for side play once more. Repeat as
necessary to get this small amount of side play. Carefully examine the large threaded portion of the piston
stem. A nylon lock can be seen imbedded in a recessed hole in the stem. It is very important that this nylon
lock can be replaced when its locking efficiency has been reduced through several disassemblies of the
piston. It is necessary to use the sharp point of a knife or some such instrument, to remove this nylon lock.