Ingersoll-Rand 3940P2Ti, Maintenance Information, Page: 2 / 8

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WARNING
Always wear eye protection when operating or performing maintenance on this tool.
Always turn off the air supply and disconnect the air supply hose before installing, removing or adjusting any accessory on this tool, or before
performing any maintenance on this tool.
Note: When reading the instructions, refer to exploded diagrams in Parts Information Manuals when applicable (see under Related
Documentation for form numbers).
Lubrication
Each time a Model 3940P2Ti Impactool is disassembled for maintenance
and repair or replacement of parts, lubricate the tool as follows:
1. Work approximately 6 cc of Ingersoll-Rand No. 170 Grease into the
impact mechanism. Coat the Anvil (40) lightly with grease around the
Hammer Case Bushing (42). Inject approximately 6 cc of grease into
the Grease Fitting.
2. Inject approximately 3 cc of No. 10 oil into the air inlet before
attaching the air hose.
Disassembly
General Instructions
1. Do not disassemble the tool any further than necessary to replace or
repair damaged parts.
2. Whenever grasping a tool or a part in a vise, always use leather-
covered or copper-covered vise jaws to protect the surface of the
part and help prevent distortion. This is particularly true of threaded
members and housings.
3. Do not remove any part which is a press fit in or on a subassembly
unless the removal of that part is necessary for repairs or
replacement.
4. Do not disassemble the tool unless you have a complete set of new
gaskets and O-rings for replacement.
Disassembly of the Impactool
1. Clamp the handle of the Impactool in a vise with the square drive
upward.
2. Remove Exhaust Deflector (4) and Silencer (5).
3. Unscrew and remove the four Hammer Case Cap Screws (45).
4. While lightly tapping on the end of the Anvil (40) with a plastic
hammer, lift off the Hammer Case Assembly (41).
5. Remove the Hammer Case Gasket (36).
6. Grasp Hammer Frame (37) and carefully lift off entire impact
mechanism, making certain not to drop the two Hammer Pins (38).
Disassembly of the Impact Mechanism
1. Set the mechanism, driver end up, on the workbench.
NOTICE
Note the twin Hammers (39) within the Hammer Frame
Assembly (37). These are identical but must be placed in
the Hammer Frame Assembly in a certain relationship.
Using a felt-tipped pen, mark the top Hammer “T
↑
” and
the bottom Hammer “B
↑
” with the arrows pointing
upward. Mark both hammers on the same end.
2. With mechanism sitting upright on the workbench, slowly rotate
Anvil (40) in a clockwise direction until it comes up solid.
NOTICE
If you continue to rotate the Anvil, it will cam the
Hammers out of engagement. Do not allow this to
happen; merely rotate the Anvil until it comes up solid.
3. Hold the Hammer Frame firmly and, without disturbing Hammers,
gently lift the Anvil, simultaneously rotating it counterclockwise about
1/8 of a turn, from the Hammer Frame.
NOTICE
The twin Hammers will be free to slide from the Hammer
Frame when the Hammer Pins (38) are removed. Do not
drop the Hammers.
4. With Anvil removed, lift out the two Hammer Pins (38).
5. Remove the twin Hammers.
Disassembly of the Reverse Valve
1. Unscrew the four Housing Cover Cap Screws (25) and remove the
Housing Cover Assembly (21), Housing Cover Gasket (27), and
Motor Clamp Washer (26).
2. Grasp the Reverse Lever (20) and withdraw the Reverse Valve
Assembly (18) from the Motor Housing Assembly (1), taking care not
to lose the Reverse Lock Plunger (23) and Reverse Lock Plunger
Spring (24).
Disassembly of the Motor
1. While holding the Impactool over the workbench , turn Impactool
to bring the square drive side upward. This will allow the motor parts
to slide out of the Motor Housing Assembly (1). If the motor parts do
not slide out freely, gently tap the side of the Motor Housing
Assembly with a plastic hammer to jar them loose. Often, all of the
motor parts except the Front End Plate (34) and Cylinder (33) will
slide out easily. Tap the Motor Housing to remove the Front End Plate
and Cylinder.
2. Inspect the Vanes (32) for wear. If a Vane is chipped or otherwise
damaged, replace the complete set.
3. Check the bore of the Cylinder and the faces of the End Plates for
scoring. Replace any scored parts.
4. Remove two Air Port Gaskets (16) and Air Port Gasket Retainers
(17) from Housing.
Disassembly of the Throttle Mechanism
1. Place the tool on the workbench with the handle pointing toward you
and the square drive side upward. Use a punch to tap out the Throttle
Valve Assembly Retaining Pin (15) from the right to the left hand side
of the handle. Pull upward on the Trigger (7) to remove the complete
Throttle Valve Assembly (6).
2. Punch out the Trigger Retaining Pin (14) from the Throttle Valve
Bushing Assembly (8) to separate Throttle Valve Assembly (6) from
the Throttle Valve Bushing Assembly.
Assembly
General Instructions
1. Always press on the inner ring of a ball-type bearing when installing
the bearing on a shaft.
2. Always press on the outer ring of a ball-type bearing when pressing
the bearing into a bearing recess.
3. Whenever grasping a tool or part in a vise, always use leather-
covered or copper-covered vise jaws. Take extra care with threaded
parts and housings.
4. Always clean every part and wipe every part with a thin film of oil
before installation.
5. Apply a film of O-ring lubricant to all O-rings before final assembly.