U.S. General 91715 User manual

1/2” IMPACT WRENCH
(MAGNESIUM, 2 HAMMER)
ASSEMBLY AND OPERATING
INSTRUCTIONS
3491 Mission Oaks Blvd., Camarillo, CA 93011
Visit our Web site at http://www.harborfreight.com
Model 91715
®
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 Freight Tools.
For technical questions and replacement parts, please call 1-800-444-3353.
TO PREVENT SERIOUS INJURY,
READ AND UNDERSTAND ALL WARNINGS
AND INSTRUCTIONS BEFORE USE.
REV 09/04

Page 2SKU 91715 For technical questions, please call 1-800-444-3353
Specifications
Save This Manual
You will need the manual for the safety warnings and precautions, assembly instruc-
tions, operating and maintenance procedures, parts list and diagram. Keep your invoice
with this manual. Write the invoice number on the inside of the front cover. Keep the
manual and invoice in a safe and dry place for future reference.
Safety Warnings and Precautions
WARNING: When using tool, basic safety precautions should always be followed to
reduce the risk of personal injury and damage to equipment.
Read all instructions before using this tool!
1. Keep work area clean. Cluttered areas invite injuries.
2. Observe work area conditions. Do not use machines or power tools in damp or wet
locations. Don’t expose to rain. Keep work area well lighted. Do not use electrically
powered compressors in the presence of flammable gases or liquids.
3. Keep children away. Children must never be allowed in the work area. Do not let
them handle machines, tools, extension cords, or air hoses.
4. Store idle equipment. When not in use, tools must be stored in a dry location to
inhibit rust. Always lock up tools and keep out of reach of children.
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. 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 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.
Torque Range 50-500 Ft. Lbs.
Drive Size 1/2”
Air Inlet 1/4” - 18 NPT
Recommended Air Pressure 90 PSI
RPM 7,500
Average Air Consumption 4 CFM
REV 05/05

Page 3SKU 91715 For technical questions, please call 1-800-444-3353
8. Do not overreach. Keep proper footing and balance at all times. Do not reach over or
across running machines or air hoses.
9. Maintain tools with care. Keep tools clean for better and safer performance. Follow
instructions for lubricating and changing accessories. Inspect tool cords and air 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 air supply. Disconnect air hose 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 plugging it in.
12. Avoid unintentional starting. Be sure the trigger is released when not in use and
before plugging in. Do not carry any tool with your finger on the trigger, whether it is
plugged in 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 any switch does not turn On and Off properly.
15. Guard against electric shock. 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 Freight
Tools.
17. Do not operate tool if under the influence of alcohol or drugs. Read warning
labels if taking prescription medicine to determine if your judgement or reflexes are
impaired while taking drugs. If there is any doubt, do not operate the Wrench.
18. Use proper size and type extension cord. If an extension cord is required, it must be
of the proper size and type to supply the correct current to the compressor without
heating up. Otherwise, the extension cord could melt and catch fire, or cause electrical
damage to the compressor. Check your air compressor’s manual for the appropriate
size cord.
19. Maintenance. For your safety, maintenance should be performed regularly by a
qualified technician.
20. Compressed air only. Never use combustible gas as a power source.
21. This Impact Wrench should only be used with impact sockets and extensions.
Using any other accessories can cause the accessories to break, causing permanent
damage to the unit and severe injury to the operator.

Page 4SKU 91715 For technical questions, please call 1-800-444-3353
Unpacking
When unpacking, check to make sure the parts listed on page 8 are included. If any
parts are missing or broken, please call Harbor Freight Tools at the number on the cover of
this manual as soon as possible.
Warning: The warnings, cautions, and instructions discussed in this instruction manual
cannot cover all possible conditions and situations that may occur. It must be under-
stood by the operator that common sense and caution are factors which cannot be
built into this product, but must be supplied by the operator.
Note: Performance of the compressor (if powered by line voltage) may vary depending
on variations in local line voltage. Extension cord usage may also affect tool perfor-
mance.
1. You will need to prepare a 1/4” air connector (not included) to connect to the Air Inlet
(408) on the Impact Wrench. First, wrap the 1/4” air connector with pipe thread seal
tape before threading it into the Air Inlet (408). Connect the 3/8” ID Air Source Hose to
a quick connect coupler (not included), and then to the Impact Wrench.
Note: If you are not using an automatic oiler system, before operation, add a few drops
of Pneumatic Tool Oil to the airline connection. Add a few drops more after each hour
of continual use.
2. Set the air pressure on the regulator to 90 PSI. Do not exceed the recommended air
pressure of 90 PSI.
3. Check the air connection for leaks. Disconnect from the air source.
Operation
For best service you should incorporate an oiler, regulator, and inline filter, as shown in the
diagram above. Hoses, couplers, oilers, regulators, and filters are all available at Harbor
Freight Tools.
Impact
Wrench

Page 5SKU 91715 For technical questions, please call 1-800-444-3353
Operation (continued)
Note: Turn off your air compressor and disconnect the air hose when you are changing
sockets. After you attach the socket, attach the air hose and turn the air compressor
on.
4. Select the appropriate size 1/2” drive socket for your needs.
5. Push and snap the socket (not included) onto the Anvil (105).
6. To operate the Forward/Reverse Lever (205) follow the directions in FIGURE 2 on page
6.
Note: Set the Forward/Reverse Lever (205) so that the anvil turns clockwise (forward).
7. Tighten the nut as tight as you can by hand.
8. Place the socket (not included) over the nut you wish to tighten.
9. Grip the Impact Wrench firmly with two hands and gently squeeze the Trigger (409).
Note: If the Impact Wrench cannot tighten the nut to your satisfaction, do not raise the air
pressure on the compressor over 90 PSI. Pressures above 90 PSI will strip the work-
piece and damage the tool, potentially causing the tool to fail, causing serious injury.
Use other appropriate methods and tools to tighten the nut.
10. When the nut is tightened, release the Trigger (409). Turn off the air compressor and
disconnect the hose.
11. If available, check the recommended torque specification for the nut. Use a torque
wrench to tighten the nut to the proper setting after using the Impact Wrench.
Loosening
Note: Set the Forward/Reverse Lever (205) so that the anvil turns counterclockwise (reverse).
12. Place the socket (not included) over the nut you wish to loosen.
13. Grip the Impact Wrench firmly with two hands and gently squeeze the Trigger (409).
Note: If the Impact Wrench cannot loosen the nut, do not raise the air pressure on the
compressor over 90 PSI. Do not attempt to loosen the nut with the Impact Wrench.
Use other appropriate methods and tools to loosen the nut.
14. When the nut is loosened, release the Trigger (409). Turn off the air compressor and
disconnect the hose.
15. If needed, remove the nut from the socket.
Refer to FIGURES 1 through 3on page 6, and the Assembly Drawing on page 8.
Warning!! This Impact Wrench supplies powerful torque and is designed to be operated with
two hands. Failure to operate the Impact Wrench with two hands may result in serious injury.

Page 6SKU 91715 For technical questions, please call 1-800-444-3353
Air Inlet (408)
Forward/Reverse
Lever (205)
Trigger (409)
Anvil (105)
FIGURE 1
FIGURE 2 FIGURE 3
ForwardReverse
Turn the Forward/Reverse Lever (205) all the way
clockwise for high speed forward.
Turn it so that it points straight up and down for
low speed forward (shown above).
Turn it all the way counterclockwise for reverse.
Grease
Fitting
(410)
1. Make sure your Impact Wrench is disconnected from the air hose before attempting
any maintenance.
2. Wipe the Impact Wrench down with a lint free cloth after each use.
3. Make sure the Anvil (105) is clear of dirt or debris. If possible, spray it with compressed
air before each use.
4. Annually, or more often if used on a daily basis, use a grease gun (not included), to
inject grease into the Grease Fitting (410). See FIGURE 3 on page 6.
5. If you do not use an inline oiler/filter system, lubricate the tool daily by holding it so that
the Air Inlet (408) is facing up. Squeeze the Trigger (409), and place one or two drops of
oil into the Air Inlet (408). Squeezing the Trigger (409) allows the oil to circulate in the
motor.
Maintenance
REV 03/05

Page 7SKU 91715 For technical questions, please call 1-800-444-3353
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 DISTRIBU-
TOR 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 REPLACE-
MENTS 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 ARIS-
ING OUT OF HIS OR HER INSTALLATION OF REPLACEMENT PARTS THERETO.
Parts List
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901gnihsuBesaCremmaH1204gniR-O1
102gnisuoH1304laeS1
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602gniR-O1804telnIriA1
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802gnirpS1014gnit
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012tloB.xeH4214relffuM1
103gniraeB1
REV 03/05

Page 8SKU 91715 For technical questions, please call 1-800-444-3353
Assembly Drawing
REV 03/05