3/8” Butterfly
Air Impact Wrench
37730
ASSEMBLY AND OPERATING INSTRUCTIONS
3491 Mission Oaks Blvd., Camarillo, CA 93011
Copyright © 2004 by Harbor Freight Tools®. All rights reserved. No portion of this
manual or any artwork contained herein may be reproduced in any shape or form
without the express written consent of Harbor FreightTools.
For technical questions and replacement parts, please call 1-800-444-3353
5. Use the right tool for the job. Do not attempt to force a small tool or
attachment to do the work of a larger industrial tool. There are certain
applications for which this tool was designed. It will do the job better
and more safely at the rate for which it was intended. Do not modify this
tool and do not use this tool for a purpose for which it was not intended.
6. Dress properly while working. Do not wear loose clothing or jewelry as
they can be caught in moving parts. Protective, electrically non-conductive
clothes and non-skid footwear are recommended when working. Wear
restrictive hair covering to contain long hair.
7. Use eye, face and ear protection. Always wear ANSI approved impact
safety goggles. Wear a full face shield if you are producing metal filings or
wood chips.Wear an ANSI approved dust mask or respirator when working
around metal, wood, and chemical dusts and mists. Wear ANSI approved ear
plugs.
8. Do not overreach. Keep proper footing and balance at all times. Do not
reach over or across running machines.
9. Maintain tools with care. Keep tools clean and in good condition for better
and safer performance. Follow instructions for lubricating and changing
accessories. Inspect tool fittings and hoses periodically and, if damaged, have
them repaired by an authorized technician. The handles must be kept clean,
dry, and free from oil and grease at all times.
10. Disconnect power.Disconnect from air pressure source when not in use.
11. Remove adjusting keys and wrenches. Check that keys and adjusting
wrenches are removed from the tool or machine work surface before
connecting it.
12. Avoid unintentional starting. Be sure the Butterfly Throttle Switch is in the
neutral, OFF position when not in use and before attaching to pressure
source. Do not carry any tool with your finger on the Butterfly Throttle Switch,
whether it is attached or not.
13. Stay alert. Watch what you are doing, use common sense. Do not operate
any tool when you are tired.
14. Check for damaged parts. Before using any tool, any part that appears
damaged should be carefully checked to determine that it will operate
properly and perform its intended function. Check for alignment and binding
of moving parts; any broken parts or mounting fixtures; and any other
condition that may affect proper operation. Any part that is damaged should
be properly repaired or replaced by a qualified technician. Do not use the tool
if the Butterfly Throttle Switch does not function properly.
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15. Guard against electric shock when working on electrical equipment,
such as your air compressor. Prevent body contact with grounded surfaces
such as pipes, radiators, ranges, and refrigerator enclosures.
16. Replacement parts and accessories. When servicing, use only identical
replacement parts. Use of any other parts will void the warranty. Only use
accessories intended for use with this tool. Approved accessories are
available from Harbor FreightTools.
17. Do not operate tool if under the influence of alcohol or drugs. Read
warning labels on prescriptions to determine if your judgment or reflexes are
impaired while taking drugs. If there is any doubt, do not operate the tool.
18. Use proper size and type air pressure line and fittings. The recommended
air line for this tool is 3/8” delivering no more than 90 psi. Recommended air
inlet size is 1/4” - 18 npt.
19. Maintenance. For your safety, service and maintenance should be performed
regularly by a qualified technician.
20. You should maintain a proper regulator and moisture trap in your air
line at all times.
Note: Performance of this tool may vary depending on variations in local air pressure.
Warning: The warnings, cautions, and instructions discussed in this instruc-
tion manual cannot cover all possible conditions and situations that may oc-
cur. It must be understood by the operator that common sense and caution
are factors which cannot be built into this product, but must be supplied by
the operator.
WARNING: The brass components of this product contain lead, a chemical
known to the State of California to cause birth defects (or other reproductive
harm). (California Health & Safety code 25249.5, et seq.)
Unpacking
When unpacking, Examine the conditiojn of your impact wrench. If any parts are
missing or broken, please call Harbor Freight Tools at the number on the cover of
th
Air Impact
Wrench
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Operation
1. Install a standard 1/4” Air Connector (not included) to the Air Inlet (36). First
wrap the threaded portion of the 1/4” air connector with pipe thread seal tape
before threading it into the Air Inlet (36).Tighten securely.
2. Attach a standard quick connector (not included) to your 3/8” air pressure
source hose. Then attach the air hose to the Air Impact Wrench.
NOTE:If you are not using an automatic in-line oiler, add a few drops of pneumatic
oil to the Air Inlet (36) before attaching the air hose. Add a few more drops of oil
after every hour of continual use.
3. Set the air pressure regulator on your air compressor at 90 psi.
WARNING: Do not exceed the recommended pressure of 90 psi.Damage to your
tool, and possible personal injury and/or property damage may result.
4. Check the air line and its connections for air leaks. Make note of these, and
repair them before using this tool.
NOTE: Turn off your air compressor and disconnect the air pressure hose before
changing sockets or making any adjustments to this tool. Severe injury or property
damage may otherwise result.
WARNING: This tool generates considerable torque when in use. Always hold the
tool with both hands when using, and brace yourself to resist the torque which will
be delivered to the work piece.
5. Select the appropriate size 3/8” square drive impact socket (not included) for
your needs. Push and snap the socket onto the Anvil (9).
6. Set the direction of the Air Impact
Wrench to “FORWARD” or
“REVERSE”. Please see photo. By
moving the Throttle Lever “Butterfly”
(5) to the right, you are setting the
tool to operate FORWARD.You may
control the amount of torque to be
applied by rotating the Regulator (38)
(See photo next page).There are
settings from 1 through 8, indicating
increasing torque. Rock the Throttle
REVERSE
Throttle Lever “Butterfly” (5)
FORWARD
Lever “Butterfly” (5) to the left to REVERSE the direction of the tool.
NOTE: In this booklet, “FORWARD” refers to clockwise rotation, and “REVERSE”
refers to counterclockwise rotation of the Anvil (9). Always be aware of the direction
of the threading of the fastener you are working on. While most fasteners install
with clockwise rotation, some threads are intentionally the reverse.
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NOTE: The actual torque delivered at each of the eight
settings will depend on the air pressure supplied to the
tool. We suggest that you test the actual torque by
tightening a nut or bolt at each setting, then observing
the resultant torque by using a mechanical torque
wrench (not supplied).
7. If installing a nut or bolt, set it as tight as possible by
hand before tightening with the Air ImpactWrench.
8. Place the socket (not included) over the fastener.
9. Grip the Air Impact Wrench tightly with both hands,
and rock the Throttle Lever “Butterfly” (5) to the
right.The tool will operate and tighten the fastener.
Regulator (38)
10. When the fastener is tightened, release the Throttle Lever “Butterfly” (5) , and
remove the tool from the fastener.
11. If possible, check the actual torque applied to the fastener with a mechanical
torque wrench (not supplied).
12. If removing a fastener, grip the Air Impact Wrench tightly with both hands, and
rock the Throttle Lever “Butterfly” (5) to the left.The tool will operate and
loosen the fastener (assuming that the fastener is a standard right-hand
thread). NOTE: Always check to be sure of the thread direction of any
fastener before attempting to install or remove it. If the fastener is a left-hand
thread, rock the Throttle Lever “Butterfly” (5) to the right for removal.
WARNING: If the fastener will not come off, first check to be sure of the
direction of the thread. If you have the thread direction correct and the fas-
tener will not come off, DO NOT INCREASETHE AIR PRESSURE to the tool
beyond 90 psi.This may damage the tool.You may have to use penetrating
oil, heat, or a mechanical wrench to remove the fastener.
13. When you are done using this tool, turn off the air compressor, and disconnect
the air hose. Put the Air Impact Wrench away in its proper storage place.
Maintenance
1. Your Air Impact Wrench should be kept clean and dry.
2. When not in use, store your tool in a suitable place where it will not be
exposed to water, corrosive materials, or undue banging around.
3. If you are not using an in-line oiler, you should inject a few drops of pneumatic
oil into the air inlet of the tool and the Oiler Screw (3) port after every hour of
continuous use.
4. If your tool loses power, or you notice air leaks, take it to a certified technician for service.
5. All repairs to this tool should be performed by a qualified service technician.
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Parts List
Item # Description
Qty.
1
Item # Description
Qty.
1
1
2
Rubber Nose Guard
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
Rear End Plate
Ball Bearing
Back Cap Gasket
Back Cap
Motor Housing
Oiler Screw
Throttle Pin
Throttle Lever
Anvil Bushing
O-Ring
1
1
3
1
1
4
2
1
5
1
Lock Washer
Cap Screw - Long
Cap Screw - Short
Plunger
4
6
1
2
7
1
2
8
Socket Retaining Ring
Anvil
1
2
9
1
Spring
2
10
11
12
13
14
15
16
17
18
19
20
21
Hammer Cage
Hammer
1
O Ring
2
1
Valve Seat
Valve Spring
O Ring
2
Cam
1
2
Hammer Pin
O-Ring
1
1
0
O Ring
1
Ball Bearing
Oil Seal
1
Air Inlet
1
0
O Ring
1
Front End Plate
Motor Pin
1
Regulator
1
1
Retainer Plate
Screw
1
Cylinder
1
2
Rotor
1
Retaining Ring
Fixing Ring
1
Rotor Blade
6
1
NOTE: Some parts are listed and shown for illustration purposes only and are not
available individually as replacement parts.
PLEASE READ THE FOLLOWING CAREFULLY
THE MANUFACTURER AND/OR DISTRIBUTOR HAS PROVIDED THE PARTS DIAGRAM
IN THIS MANUAL AS A REFERENCE TOOL ONLY. NEITHER THE MANUFACTURER NOR
DISTRIBUTOR MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND TO THE
BUYER THAT HE OR SHE IS QUALIFIED TO MAKE ANY REPAIRS TO THE PRODUCT OR
THAT HE OR SHE IS QUALIFIED TO REPLACE ANY PARTS OF THE PRODUCT. IN FACT,
THE MANUFACTURER AND/OR DISTRIBUTOR EXPRESSLY STATES THAT ALL REPAIRS
AND PARTS REPLACEMENTS SHOULD BE UNDERTAKEN BY CERTIFIED AND
LICENSED TECHNICIANS AND NOT BY THE BUYER. THE BUYER ASSUMES ALL RISK
AND LIABILITY ARISING OUT OF HIS OR HER REPAIRS TO THE ORIGINAL PRODUCT
OR REPLACEMENT PARTS THERETO, OR ARISING OUT OF HIS OR HER INSTALLATION
OF REPLACEMENT PARTS THERETO.
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Assembly Drawing
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Page 8
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