Ingersoll Rand Impact Driver 3940 User Manual

10569408

Edition 1

January 2006

Air Impact Wrench

Series 3940, 3942 & 3955

Maintenance Information

Save These Instructions

9. Remove two Air Port Gaskets (29) and Air Port Gasket

Retainers (28) from Housing.

WARNING

Disassembly of the Handle

The following procedure requires the use of heat. Take

all necessary precautions to prevent burns. Carefully

heat alternate sides of Housing until it is very warm.

Using thick, heavy gloves to avoid being burned, grasp

Housing and repeat attempt to dislodge Cylinder.

1. Clamp Trigger Handle Assembly in leather-covered or copper-

covered vise jaws with the Straight Inlet (10) upward.

2. Using a wrench, unscrew and remove Inlet as well as Air Strainer

Screen (9) and valve Spring (8).

3. Remove Throttle Valve Assembly (6) and Valve Plunger (5) from

Handle.

4. If Trigger (3) must be removed, use an arbor press to push Trigger

Pin (4) from the Handle and slide Trigger out of slot in Handle.

8. Open a set of vise jaws wide enough to clear hub of Front End Plate

and sharply rap hub end of end plate on top of jaws to dislodge Front

Rotor Bearing.

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 installing

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

members and housings.

4. Always clean every part and wipe every part with a thin film of oil

before installation.

9. Coat inside of Cylinder and Rotor (22) with a light film of oil and insert

the splined hub of Rotor through Cylinder into Front End Plate.

10. Coat each Vane (23) with a light film of oil and insert a Vane into each

slot in the Rotor. Vanes must be installed with curved edge toward

center of Rotor. Spin the Rotor to settle Vanes in position.

11. Using long tee hex wrench to align hole in Rear End Plate (20) with

hole in Cylinder, insert the Rear End Plate, bronze face leading, into

Motor Housing against the Cylinder. End Plate is properly seated

when large trailing face of End Plate is slightly below face of Motor

Housing.

5. Apply a film of O-ring lubricant to all O-rings before final assembly.

12. Grease Rear Rotor Bearing (18) and install it in recess of Rear End

Plate.

Assembly of the Handle

13. Remove alignment pin from assembled motor and install Cylinder

Dowel (19). The Dowel is properly seated when end of Dowel does

not protrude above End Plate.

14. Install Motor Clamp Washer(s) (16) against Rear End Plate so that

large outer edge of Washer contacts End Plate.

1. Position Trigger (3) in Handle (1) and using an arbor press, push

Trigger Pin (4) full length into Handle so that it captures Trigger.

2. Clamp Handle in leather-covered or copper-covered vise jaws with

air inlet opening upward.

3. Coat Throttle Valve Plunger (5) with oil and insert it, rounded end

leading, into the inlet hole in Handle.

Assembly of the Reverse Valve

4. Install a new Throttle Valve Seal (7) on Throttle Valve (6) and insert

assembly, Valve Seal leading, into inlet hole in Handle.

5. Encircle cone end of Air Strainer Screen (9) with large end of Throttle

Valve Spring (8) and insert both parts, Spring leading, into the inlet

hole in Handle.

1. Inject a small amount of grease into hole in Motor Housing (26)

where Reverse Lock Plunger (30) will be installed. With grease to

hold them in position, install Reverse Lock Plunger Spring (31) and

Lock Plunger.

6. Install Straight Inlet (10) over Strainer Screen in Handle and tighten

Inlet between 50 and 60 ft-lb (68 and 81 Nm) torque.

2. Install a new Reverse Valve Bushing Seal (14) in annular groove on

Reverse Valve (13).

7. Remove Handle from vise and test Trigger. If Trigger functions

properly, place assembled Handle aside. If it does not function

properly, disassemble Handle to determine cause of problem.

3. Coat Reverse Valve with a light film of oil and install it in Motor

Housing with the side hole nearest to Seal pointed toward Rotor (22).

4. Position Reverse Lever (12) on Reverse Valve and while using a thin

blade screwdriver to depress Reverse Lock Plunger, push Lever onto

Reverse Valve.

Assembly of the Motor

5. Place a new Handle Gasket (17) on the Motor Housing.

6. Examine Reverse Valve Seal (11) located inside Handle and if it is

nicked, deformed or worn, remove it and install a new Seal.

7. Fill rotor cavity in Handle with recommended grease and position

Handle on the Motor Housing.

8. For 3940 and 3942 Series: Install four Handle Cap Screws (15) and

using an alternate tightening pattern, tighten Screws to between 10

and 12 ft-lb (14 and 16 Nm) torque.

For 3955 Series: Install four Handle Cap Screws (15) and using an

alternate tightening pattern, tighten Screws to between 25 and 28 ft-

lb (34 and 38 Nm) torque.

9. Move Reverse Lever through the forward and reverse positions to

make certain the Lever locks in position.

1. Lightly clamp Motor Housing (26) in leather-covered or copper-

covered vise jaws with handle end upward.

NOTICE

Excessive clamping pressure will distort the Motor

Housing and make motor installation extremely difficult.

Do not insert the hammer case end of the Motor

Housing more than 1” (25 mm) into the vise jaws.

2. Grease Front Rotor Bearing (25) and install it in recess of Front End

Plate.

3. Coat inside surface of Housing and outer edge of

Front End Plate (24) with a light film of oil.

10. Turn assembly in vise jaws and clamp on Handle with rotor shaft

upward.

4. Using a long tee hex wrench as an alignment pin, insert Front End

Plate, copper face trailing, into Motor Housing. Align dowel hole in

End Plate with dowel hole at the bottom of motor bore.

5. Lubricate and insert a new fiber Air Port Gasket Retainer (28) in one

of the air ports inside Motor Housing.

11. Pack Front Rotor Bearing with additional grease and rotate rotor

shaft. If shaft does not rotate smoothly, rap end of rotor shaft with a

soft hammer to set motor and try to rotate shaft again.

6. Install an Air Port Gasket (29) in the air port against Gasket Retainer

with flat end of Gasket away from Retainer.

7. Repeat Steps 5 and 6 to install remaining Gasket and Retainer in the

other air port.

8. Coat outside of Cylinder (21) with a light film of oil and using long tee

hex wrench as an alignment pin to align the holes in Cylinder with

holes in Front End Plate and Housing, insert Cylinder into Housing.

10569408_ed1

1. Coat Hammers (37) with a light film of Ingersoll-Rand Impactool

Grease No. 170.

Assembly of the Impact Mechanism

2. Replace Hammers in Hammer Frame (35) exactly as they were

when you marked them prior to disassembly.

NOTICE

If you are installing new Hammers, or want to change

the location of the existing Hammers to utilize both

impacting surfaces, slide the Hammers in the Hammer

Frame so that the half-round notch on one Hammer is

located on one side of the Frame and the half-round

notch on the other Hammer is located on the other side

of the Frame.

3. Replace Hammer Pins (36).

4. Examine base of Anvil (38) and note its contour. While looking down

through Hammer Frame, swing the top Hammer to its full extreme

one way or another until you can match the contour of the Anvil.

Enter the Anvil into the Hammer Frame and through the first

Hammer. Swing the bottom Hammer in opposite direction from the

top Hammer and maneuver Anvil slightly until it drops into bottom

Hammer.

TOP HAMMER

WIDE BEVEL UP

TOP HAMMER

HALF–ROUND NOTCH ON

Assembly of the Impactool

RIGHT

1. Set assembled hammer mechanism onto rotor shaft spline.

2. Place Hammer Case Gasket (34) over mechanism and against face

of Motor Housing.

3. Grease Anvil and top of Hammer Frame.

4. Place Hammer Case (39) over mechanism assembly against

Gasket.

5. Assemble Dead Handle (43) to Dead Handle Bracket (42). Insert two

Hammer Case Cap Screws (41). Position assembly against Hammer

Case and thread the Screws into Housing.

BOTTOM HAMMER

WIDE BEVEL DOWN

6. For 3940 and 3942 Series: Thread remaining two Cap Screws into

Housing and using an alternating pattern for all four fasteners, tighten

Screws between 20 and 25 ft-lb (27 and 34 Nm) torque.

For 3955 Series: Thread remaining two Cap Screws into Housing

and using an alternating pattern for all four fasteners, tighten Screws

between 35 and 40 ft-lb (47 and 54 Nm) torque.

BOTTOM HAMMER

HALF–ROUND NOTCH ON LEFT

7. Install a new Exhaust Silencer (33) in Motor Housing Assembly (26)

and install the Exhaust Deflector (32).

(Dwg. TPD652)

Troubleshooting Guide

Trouble

Probable Cause

Solution

Low power

Dirty Inlet Bushing or Air Strainer Screen and/or

Exhaust Silencer.

Using a clean, suitable, cleaning solution, in a well ventilated

area, clean Air Strainer Screen, Inlet Bushing and Exhaust

Silencer.

Worn or broken Vanes.

Replace the complete set of Vanes.

Worn or broken Cylinder and/or scored End Plates.

Examine the Cylinder and replace it if it is worn or broken or

if the bore is scored or wavy. Replace the End Plates if they

are scored.

Dirty motor parts.

Disassemble tool and clean all parts with a suitable cleaning

solution, in a well-ventilated area. Reassemble tool as

instructed in this manual.

Improper positioning of the Reverse Valve.

Incorrect assembly of the motor.

Make certain that the Reverse Valve is fully engaged to the

left or right.

Motor will not run

Disassemble the motor and replace worn or broken parts

and reassemble as instructed.

Insufficient lubricant in the impact mechanism.

Broken or worn impact mechanism parts.

Impact Mechanism not assembled correctly.

Remove the Hammer Case Assembly and lubricate the

impact mechanism.

Tool will not impact

Remove the Hammer Case and examine the impact

mechanism parts. Replace any worn or broken parts.

Refer to Assembly of the Impact Mechanism.