Chicago Electric 91790 User manual

Heavy Duty ImpactHeavy Duty Impact
Heavy Duty ImpactHeavy Duty Impact
Heavy Duty Impact
Wrench 1” - 24 VWrench 1” - 24 V
Wrench 1” - 24 VWrench 1” - 24 V
Wrench 1” - 24 V
ASSEMBLY AND OPERATING INSTRUCTIONS
3491 Mission Oaks Blvd., Camarillo, CA 93011
Visit our Web site at http://www.harborfreight.com
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.
91790

SKU91790 Page2For technical questions, please call 1-800-444-3353.
This tool is ideal for use by truckers and others who operate a 24 volt
system, and who must remove and install bolts or nuts of 1-1/2” or 1-5/8” size, such
as wheel lugs.
This tool can be driven off a 24 Volt battery, provides up to 664 ft.lbs.of
torque and is reversible.The power cord has battery clamps included.
SaveThis Manual
You will need the manual for the safety warnings and precautions, assem-
bly instructions, 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 refer-
ence.
SafetyWarnings and Precautions
WARNING: When using tool, basic safety precautions should always be fol-
lowed to reduce the risk of personal injury and damage to equipment.
Read all instructions before using this tool!
1. Keep work area clean. Clutteredareas invite injuries.
2. Observe work area conditions. Donot use machines orpower toolsin damp
or wet locations. Don’t expose to rain. Keep work area well lit. Do not use
electrically powered tools in the presence of flammable gases or liquids.
3. Keep children away. Children must neverbeallowedin theworkarea. Do not
let them handle machines, tools, or extension cords.
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
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NOTE:Unlike air-operated or 120V AC impact wrenches,thisWrench will build
up inertia before striking a blow.This is normal,and DOES NOT INDICATE
A PROBLEM.
Specifications

SKU91790 Page3For technical questions, please call 1-800-444-3353.
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. Donot wearlooseclothing or jewelryastheycan be caught in
moving parts. Protective, electrically non-conductive clothes and non-skid
footwear are recommended when working. Wear restrictive hair covering to
containlonghair.
7. Useeyeand earprotection. AlwayswearANSIapprovedimpactsafetygoggles.
Wear a full face shield if you are producing metal filings or wood chips. Wear
appropriatesafetyequipmentwhenworkingaroundvehiclebatteries.
8. Do not overreach. Keep proper footing and balance at all times.Do not reach
overor across running machines.
9. Maintain tools with care. Keep tools clean and in good repair for better and
saferperformance.Follow instructions forlubricatingandchangingaccessories.
Inspect tool cords 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 tool from the battery when not in use.
11. Remove adjusting keys and wrenches. Check that keys and adjusting
wrenchesareremovedfrom the toolormachineworksurfacebeforeconnecting
it.
12. Avoid unintentional starting. Be sure the trigger is released when not in use
and before connecting to the battery. Do not carry any tool with your finger on
the trigger, whether or not it is connected.
13. Stay alert. Watchwhat you aredoing, use common sense.Donot operateany
toolwhen you are tired.
14. Checkfordamagedparts. Beforeusinganytool,anypartthatappearsdamaged
shouldbecarefullycheckedtodeterminethatitwilloperateproperlyandperform
its intended function. Check for alignment and binding of moving parts; any
brokenpartsormountingfixtures;andanyother condition thatmayaffect proper
operation.Anypart that isdamaged should be properly repairedor replaced by
aqualifiedtechnician.Do notusethetoolifthetrigger does not operateproperly.
15. Guard against electric shock. Prevent body contact with grounded surfaces
such as engine block, fender or other vehicle parts. Prevent the leads from
touchingeachother.
16. Replacement parts and accessories. When servicing, use only identical
replacement parts. Use of any other parts will void the warranty. Only use
accessoriesintendedfor use with this tool.Approvedaccessories are available
fromHarborFreightTools.

SKU91790 Page4For technical questions, please call 1-800-444-3353.
17. Donotoperate tool ifunderthe influence of alcoholor drugs. Readwarning
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. Maintenance. Foryour safety,service and repairs mustbe performed onlybya
qualifiedtechnician.Maintenanceshould be performed on aregularbasis.
19. Industrial applications must follow OSHA guidelines.
20. People with pacemakers should consult their physician(s) before using
this product. Electromagnetic fields in close proximity to a heart pacemaker
could cause interference to or failure of the pacemaker.
21. 24V systems only. This unit should only be powered by 24Volt DC systems.
Warning:The warnings,cautions,and instructions discussed in thisinstruction
manual cannot cover all possible conditions and situations that may occur. It
must be understood by the operator that common sense and caution are fac-
tors which cannot be built into this product, but must be supplied by the opera-
tor.
Unpacking
When unpacking, check to make sure the following parts are included.
Heavy Duty ImpactWrench 6-Point Impact Sockets (1-1/2”and 1-5/8”)
8”extension CarryingCase(notshownbelow)
If any parts are missing or broken, please call Harbor FreightTools at the
number on the cover of this manual.
8”Extension
6-Point
Impact
Sockets
Heavy Duty Impact Wrench

SKU91790 Page5For technical questions, please call 1-800-444-3353.
Operation
1. Prior to use, be sure that your vehicle or other work object is safely secured in
preparationfor maintenance.
2. This tool operates on 24 volts DC.This power level is commonly available from
the battery of large transport trucks and other vehicles. Do not attempt to use
this tool with any other voltage.
3. When it is safe to do so, connect the RED clamp of this tool to the POSITIVE
terminal of a 24 volt battery. Connect the BLACK clamp of this tool to a clean
grounded part of the vehicle such as the engine block or frame member.
NOTE: If the engine is left running while performing this operation, be sure to avoid
placing your hands, clothes, hair or any other appendage in close proximity to the
movingparts of the engine.The engine shouldonlyberuninanopen,well-ventilated
place.
WARNING:Workingaroundvehicleengineswhether runningor notisinherentlydan-
gerous,andextraordinaryprecautionsoutsidethescopeofthisbookletarerequired.
Referto the owners’manual of yourvehicle for moreinformation.
ImpactWrench, with 8”Extension and Impact Socket Installed
4. NOTE: Unlike air-operated or 120V AC impact wrenches,this
wrench will build up inertia before striking a blow. This is
normal, and DOES NOT INDICATE A PROBLEM.
5. Make sure the vehicle is parked safely away from all other moving traffic. Be
sure the vehicle is parked on a flat, dry, level surface.Be sure the vehicle is out
of gear (in Neutral), the vehicle’s emergency brake is set, and the tires have
wheelblockspreventing movement.

SKU91790 Page6For technical questions, please call 1-800-444-3353.
6. Select the appropriate size socket to fit the wheel lug nut. If necessary, install
an extension.Attach the extension and socket to the ImpactWrench by press-
ing them on to the Drive Shaft (29).
7. Positionan appropriatelift(notincluded)under the lift point foreach wheel to be
removed. (Follow the vehicle and lift manufacturer’s instructions for doing so.)
Lift the vehicle until the wheel is off the ground, and support the vehicle se-
curely.
8. The Impact Wrench is reversible. To operate the Impact Wrench in a forward
(tightening)direction, squeezethelowerhalf oftheTrigger (8)while holding the
tool securely in your hands.To operate the ImpactWrench in reverse direction,
squeeze the upper half of theTrigger (8) while holding the tool securely in your
hands. Using the ImpactWrenchin reverse,removethewheel lug nuts accord-
ing to the manufacturer’s recommendations. (In most cases, the manufacturer
willrecommendthat you removethelugsinanalternate pattern, moving around
thewheel.)
9. Occasionally, you will have to manually break a nut loose before you can re-
move it with the ImpactWrench.To do so, use a Breaker Bar (not included) and
Socket to break the nut loose.Then, proceed as discussed in item 9 above.
10. Replace the wheel on the vehicle hub, aligning the wheel studs with the bolt
holes in the wheel.
11. Install the wheel lug nuts, following the vehicle manufacturer’s recommenda-
tions. Threadthenutsonby handfirst beforeusingtheImpactWrenchto avoid
cross-threading them. Be sure to adhere to the vehicle manufacturer’s recom-
mendedtorquerequirements for tightening the lugnuts.
12. When the wheel is securely refastened, use a torque wrench (not included) to
check the torque on all bolts and ensure that the tightness meets the
manufacturer’s recommendations. Lower the vehicle, disconnect the tool and
replace the lift and the ImpactWrench to their storage places.
Maintenance
1. When not in use, store your Impact Wrench and its accessories in its case, in
a secure, dry place.Protect it from water, moisture, oil, fuel, grease or other
foreign materials which may damage the case, moving parts, or electrical
components.
2. This tool should only be repaired by a qualified technician.

SKU91790 Page7For technical questions, please call 1-800-444-3353.
Parts List
NOTE: Some parts are listed and shown for illustration purposes only and are not available
individually as replacement parts.
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SKU91790 Page8For technical questions, please call 1-800-444-3353.
Assembly Drawing
PLEASE READTHE FOLLOWING CAREFULLY
THE MANUFACTURER AND/OR DISTRIBUTOR HAS PROVIDED THE PARTS DIA-
GRAM IN THIS MANUAL AS A REFERENCE TOOL ONLY. NEITHER THE MANUFACTURER
NOR DISTRIBUTOR MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND TO THE
BUYERTHAT HE OR SHE IS QUALIFIED TO MAKE ANY REPAIRSTOTHE PRODUCT ORTHAT
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 TECH-
NICIANS AND NOT BYTHE 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.