Central Pneumatic Earthquake 92421 Installation manual

1” AIR IMPACT WRENCH
92421
SET UP AND OPERATING INSTRUCTIONS
Visit our website at: http://www.harborfreight.com
Read this material before using this product.
Failure to do so can result in serious injury.
SAVE THIS MANUAL.
Copyright©2009 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. Diagrams within this manual may not be drawn proportionally. Due to continuing
improvements, actual product may differ slightly from the product described herein. Tools required for
assembly and service may not be included.
For technical questions or replacement parts, please call 1-800-444-3353.
Revised Manual 11h

Page 2 For technical questions, please call 1-800-444-3353. SKU 92421
SAVE THIS MANUAL
Keep this manual for the safety
warnings and precautions, assembly,
operating, inspection, maintenance and
cleaning procedures. Write the product’s
serial number in the back of the manual
near the assembly diagram (or month
and year of purchase if product has no
number). Keep this manual and the
receipt in a safe and dry place for future
reference.
Safety Alert Symbol and Signal
Words
In this manual, on the labeling,
and all other information
provided with this product:
This is the safety alert
symbol. It is used to alert
you to potential personal
injury hazards. Obey all
safety messages that
follow this symbol to avoid
possible injury or death.
DANGER indicates
a hazardous
situation which, if not
avoided, will result in death or
serious injury.
WARNING
indicates a
hazardous situation which, if
not avoided, could result in
death or serious injury.
CAUTION, used
with the safety
alert symbol, indicates a
hazardous situation which, if
not avoided, could result in
minor or moderate injury.
NOTICE is used to
address practices
not related to personal injury.
CAUTION, without
the safety alert
symbol, is used to address
practices not related to
personal injury.
IMPORTANT SAFETY
INSTRUCTIONS
INSTRUCTIONS PERTAINING
TO A RISK OF FIRE,
ELECTRIC SHOCK, OR
INJURY TO PERSONS
WARNING – When using tools, basic
precautions should always be
followed, including the following:
General
a. To reduce the risks of electric
shock, re, and injury to persons,
read all the instructions before
using the tool.
Work area
a. Keep the work area clean and well
lighted. Cluttered benches and dark
areas increase the risks of electric
shock, re, and injury to persons.
b. Do not operate the tool in
explosive atmospheres, such as in
the presence of ammable liquids,
gases, or dust. The tool is able to
create sparks resulting in the ignition
of the dust or fumes.
c. Keep bystanders, children, and
visitors away while operating the

Page 3For technical questions, please call 1-800-444-3353.SKU 92421
tool. Distractions are able to result in
the loss of control of the tool.
Personal safety
a. Stay alert. Watch what you are
doing and use common sense
when operating the tool. Do not
use the tool while tired or under
the inuence of drugs, alcohol, or
medication. A moment of inattention
while operating the tool increases the
risk of injury to persons.
b. Dress properly. Do not wear loose
clothing or jewelry. Contain long
hair. Keep hair, clothing, and
gloves away from moving parts.
Loose clothes, jewelry, or long hair
increases the risk of injury to persons
as a result of being caught in moving
parts.
c. Avoid unintentional starting.
Be sure the switch is off before
connecting to the air supply. Do not
carry the tool with your nger on the
switch or connect the tool to the air
supply with the switch on.
d. Remove adjusting keys and
wrenches before turning the tool
on. A wrench or a key that is left
attached to a rotating part of the tool
increases the risk of personal injury.
e. Do not overreach. Keep proper
footing and balance at all times.
Proper footing and balance
enables better control of the tool in
unexpected situations.
f. Use safety equipment. A
dust mask, non-skid safety
shoes and a hard hat must
be used for the applicable
conditions. Wear heavy-duty work
gloves during use.
g. Always wear eye
protection. Wear ANSI-
approved safety goggles.
h. Always wear hearing
protection when using
the tool. Prolonged
exposure to high intensity
noise is able to cause hearing loss.
Tool use and care
a. Use clamps or another practical
way to secure and support the
workpiece to a stable platform.
Holding the work by hand or against
the body is unstable and is able to
lead to loss of control.
b. Do not force the tool. Use the
correct tool for the application. The
correct tool will do the job better and
safer at the rate for which the tool is
designed.
c. Do not use the tool if the Trigger
does not turn the tool on or off.
Any tool that cannot be controlled
with the switch is dangerous and
must be repaired.
d. Disconnect the tool from the
air source before making
any adjustments, changing
accessories, or storing the tool.
Such preventive safety measures
reduce the risk of starting the tool
unintentionally. Turn off and detach
the air supply, safely discharge any
residual air pressure, and release the
throttle and/or turn the switch to its off
position before leaving the work area.

Page 4 For technical questions, please call 1-800-444-3353. SKU 92421
e. Store tool when idle and out
of reach of children and other
untrained persons. A tool is
dangerous in hands of untrained
users.
f. Maintain the tool with care. A
properly maintained tool is easier to
control.
g. Check for misalignment or binding
of moving parts, breakage of
parts, and any other condition
that affects the tool’s operation. If
damaged, have tool serviced before
using. Many accidents are caused
by poorly maintained tools. There is a
risk of bursting if the tool is damaged.
h. Use only accessories that are
identied by the manufacturer for
the specic tool model. Use of an
accessory not intended for use with
the specic tool model, increases the
risk of injury to persons.
Service
a. Tool service must be performed
only by qualied repair personnel.
b. When servicing a tool, use only
identical replacement parts. Use
only authorized parts.
c. Use only the lubricants supplied
with the tool or specied by the
manufacturer.
Air source
a. Never connect to an air
source that is capable of
exceeding 90 psi. Over
pressurizing the tool may
cause bursting, abnormal operation,
breakage of the tool or serious injury
to persons. Use only clean, dry,
regulated compressed air at the rated
pressure or within the rated pressure
range as marked on the tool. Always
verify prior to using the tool that the
air source has been adjusted to the
rated air pressure or within the rated
air-pressure range.
b. Never use oxygen, carbon dioxide,
combustible gases or any bottled
gas as an air source for the tool.
Such gases are capable of explosion
and serious injury to persons.
SAVE THESE
INSTRUCTIONS.
SYMBOLS AND
SPECIFIC SAFETY
INSTRUCTIONS
Symbol Denitions
Symbol Property or statement
noNo-load speed
.../min Revolutions or reciprocation per
minute
PSI Pounds per square inch of pressure
ft-lb Foot-pounds of torque
BPM Blows per minute
CFM Cubic Feet per Minute ow
SCFM Cubic Feet per Minute ow at
standard conditions
NPT National pipe thread, tapered
NPS National pipe thread, straight
Chart continued in next column.

Page 5For technical questions, please call 1-800-444-3353.SKU 92421
Symbol Denitions
Symbol Property or statement
WARNING marking concerning Risk
of Eye Injury. Wear ANSI-approved
eye protection.
WARNING marking concerning Risk
of Hearing Loss. Wear hearing
protection.
WARNING marking concerning Risk
of Respiratory Injury. Wear NIOSH-
approved dust mask/respirator.
WARNING marking concerning Risk
of Explosion.
Specic Safety Instructions
1. The warnings and precautions
discussed in this manual cannot
cover all possible conditions and
situations that may occur. 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.
2. Hold Impact Wrench with BOTH
hands during use. Failure to do so
can lead to loss of control, which can
cause personal injury and/or property
damage.
3. 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.)
4. Only use with accessories rated to
handle the forces exerted by this tool
during operation. Other accessories
not designed for the forces generated
may break and forcefully launch
pieces.
5. Attach all accessories properly to the
tool before connecting the air supply.
A loose accessory may detach or
break during operation.
6. Obey the manual for the air
compressor used to power this tool.
7. Install an in-line shutoff valve to allow
immediate control over the air supply
in an emergency, even if a hose is
ruptured.
8. Do not lay the tool down until it has
come to a complete stop. Moving
parts can grab the surface and pull
the tool out of your control.
Vibration Precautions
This tool vibrates during use.
Repeated or long-term exposure to
vibration may cause temporary or
permanent physical injury, particularly to
the hands, arms and shoulders. To reduce
the risk of vibration-related injury:
1. Anyone using vibrating tools regularly
or for an extended period should
rst be examined by a doctor and
then have regular medical check-
ups to ensure medical problems are
not being caused or worsened from
use. Pregnant women or people
who have impaired blood circulation
to the hand, past hand injuries,
nervous system disorders, diabetes,
or Raynaud’s Disease should not use
this tool. If you feel any symptoms
related to vibration (such as tingling,
numbness, and white or blue ngers),
seek medical advice as soon as
possible.

Page 6 For technical questions, please call 1-800-444-3353. SKU 92421
2. Do not smoke during use. Nicotine
reduces the blood supply to the
hands and ngers, increasing the risk
of vibration-related injury.
3. Wear suitable gloves to reduce the
vibration effects on the user.
4. Use tools with the lowest vibration
when there is a choice.
5. Include vibration-free periods each
day of work.
6. Grip tool as lightly as possible (while
still keeping safe control of it). Let
the tool do the work.
7. To reduce vibration, maintain tool as
explained in this manual. If abnormal
vibration occurs, stop immediately.
SAVE THESE
INSTRUCTIONS.
FUNCTIONAL DESCRIPTION
Specications
Maximum Air Pressure 90 PSI
Air Inlet 1/2” -14 NPT
Drive Size 1” Square Drive
Maximum Speed* 5400 RPM
Average Air Consumption 8 SCFM @ 90 PSI
Maximum Torque 1800 ft-lb
Torque Range 400-1500 ft-lb
Blows Per Minute (BPM) 1080 (Approx.)
Bolt Capacity 1-3/8”
Recommended Air Hose 1/2”
* Maximum speed at stated maximum air pressure.
Excess air pressure is hazardous and may cause the
tool to exceed stated maximum speed.
INITIAL TOOL SET UP/
ASSEMBLY
Read the ENTIRE IMPORTANT
SAFETY INFORMATION
section at the beginning of this
manual including all text under
subheadings therein before set
up or use of this product.
Note: For additional information regarding
the parts listed in the following pages,
refer to the Assembly Diagram near
the end of this manual.
Unpacking
When unpacking, make sure that the
item is intact and undamaged. If any parts
are missing or broken, please call Harbor
Freight Tools at 1-800-444-3353 as soon
as possible.
• This air tool may be shipped with a
protective plug covering the air inlet.
Remove this plug before set up.

Page 7For technical questions, please call 1-800-444-3353.SKU 92421
Air Supply
TO PREVENT
EXPLOSION:
Use only clean, dry, regulated,
compressed air to power this
tool. Do not use oxygen,
carbon dioxide, combustible
gases, or any other bottled
gas as a power source for this
tool.
Quick
Coupler
Recommended Air Line Components
Regulator with
Pressure Gauge
Quick
Coupler Air Hose
on Reel
Valve FilterOiler
Coupler
Plug
Tool
Air
Compressor
Coupler
Plug
1. Incorporate a lter, regulator with
pressure gauge, oiler, in-line shutoff
valve, and quick coupler for best
service, as shown in the diagram
above. An in-line shutoff ball
valve is an important safety device
because it controls the air supply
even if the air hose is ruptured.
The shutoff valve should be a ball
valve because it can be closed
quickly.
Note: If an automatic oiler system is not
used, add a few drops of Pneumatic
Tool Oil to the airline connection
before operation. Add a few more
drops after each hour of continual
use.
2. Attach an air hose to the
compressor’s air outlet. Connect the
air hose to the air inlet of the tool.
Other components, such as a coupler
plug and quick coupler, will make
operation more efcient, but are not
required.
WARNING! TO PREVENT SERIOUS
INJURY FROM ACCIDENTAL
OPERATION:
Do not install a female quick
coupler on the tool. Such a coupler
contains an air valve that will allow
the air tool to retain pressure and
operate accidentally after the air
supply is disconnected.
Note: Air ow, and therefore tool
performance, can be hindered by
undersized air supply components.
3. The air hose must be long enough
to reach the work area with enough
extra length to allow free movement
while working.
4. Release the tool’s Trigger (13); refer
to Operation section for description of
controls.
5. Close the in-line safety valve between
the compressor and the tool.
6. Turn on the air compressor according
to the manufacturer’s directions and
allow it to build up pressure until it
cycles off.
7. Adjust the air compressor’s output
regulator so that the air output is
enough to properly power the tool,
but the output will not exceed the
tool’s maximum air pressure at any
time. Adjust the pressure gradually,

Page 8 For technical questions, please call 1-800-444-3353. SKU 92421
while checking the air output gauge
to set the right pressure range.
8. Inspect the air connections for leaks.
Repair any leaks found.
9. If the tool will not be used at this
time, turn off and detach the air
supply, safely discharge any
residual air pressure, and release
the throttle and/or turn the switch to
its off position to prevent accidental
operation.
10. Drain the compressor regularly.
Note: Residual air pressure should not be
present after the tool is disconnected
from the air supply. However, it is a
good safety measure to attempt to
discharge the tool in a safe fashion
after disconnecting to ensure that the
tool is disconnected and unpowered.
Assembly
1. While main body of Impact Wrench
does come assembled, the Side
Handle (45) needs to be fastened to
the side of Hammer Case (43).
2. Attach Washers (46A) to Screws
(46). Position Handle (45) against
Hammer Case, attach Screws and
then securely tighten.
OPERATING INSTRUCTIONS
Read the ENTIRE IMPORTANT
SAFETY INFORMATION
section at the beginning of this
manual including all text under
subheadings therein before set
up or use of this product.
Inspect tool before use, looking
for damaged, loose, and
missing parts. If any problems
are found, do not use tool until
repaired.
Tool Set Up
TO PREVENT
SERIOUS INJURY
FROM ACCIDENTAL
OPERATION: Turn off the tool,
detach the air supply, safely
discharge any residual air
pressure in the tool, and
release Trigger before
performing any inspection,
maintenance, or cleaning
procedures.
TO PREVENT SERIOUS
INJURY: Do not adjust or
tamper with any control or
component in a way not
specically explained within
this manual. Improper
adjustment can result in
tool failure or other serious
hazards.
Work Piece and Work Area Set Up
1. Designate a work area that is clean
and well-lit. The work area must not
allow access by children or pets to
prevent distraction and injury.
2. Route the air hose along a safe
route to reach the work area without
creating a tripping hazard or exposing
the air hose to possible damage.
The air hose must be long enough
to reach the work area with enough
extra length to allow free movement
while working.
3. There must not be hazardous objects
(such as utility lines or foreign

Page 9For technical questions, please call 1-800-444-3353.SKU 92421
objects) nearby that will present a
hazard while working.
General Operating Instructions
1. WARNING! Use only 1” Drive Impact
type sockets (sold separately).
2. WARNING! The Impact Wrench is
heavy and supplies powerful amounts
of torque and should be operated
with BOTH hands. Failure to do
so can lead to personal injury or
property damage.
3. If an automatic oiler is not used, add
a few drops of Pneumatic Tool Oil
to the airline connection before use.
Add a few drops more after each
hour of continual use.
4. Push and snap the socket (not
included) onto the Anvil (38).
5. The Direction Valve (17) has three
forward and three reverse speed
settings Turn Direction Valve to the
right toward the Trigger Handle (1) to
tighten. See Figure 1, below.
6. Place the socket over the nut you
wish to tighten.
7. Grip tool rmly with BOTH hands and
gently squeeze Trigger (13).
8. Adjust air ow by turning Air
Regulator Knob from positions 1
through 3. Position 1 allows the
lowest amount of air ow, and
Position 3 the highest.
9. If the tool requires more force to
accomplish task, verify that the tool
receives sufcient, unobstructed
airow (CFM) and increase the
pressure (PSI) output of the regulator
up to the maximum air pressure
rating of this tool.
CAUTION! TO PREVENT TOOL
AND ACCESSORY FAILURE,
RESULTING IN INJURY:
Do not exceed the tool’s maximum
air pressure rating.
If the tool still does not have sufcient
force at maximum pressure and
sufcient airow, then a larger tool
may be required.
10. Once nut is tightened, release
Trigger. Turn off the air supply and
disconnect the hose.
11. If available, check the recommended
torque specication for the nut. Use
a torque wrench to tighten the nut
to the proper setting after using the
Impact Wrench.
12. To set Impact Wrench in Reverse,
slide Direction Valve to the left and
away from the Trigger Handle for
counterclockwise (reverse) rotation.
13. WARNING! Before changing the
rotational direction of the tool, release
the Trigger and allow Tool to come to
a complete stop.
14. Adjust air ow by turning Air
Regulator Knob from positions 1
To Trigger
Handle (1)
Direction Valve (17)
Reverse
Setting
Figure 1
Forward
Setting
Please Note: Figure 1 (view from side of tool)
shows Settings above Direction Valve without
protective black coating.

Page 10 For technical questions, please call 1-800-444-3353. SKU 92421
through 3. Position 1 allows the
lowest amount of air ow, and
Position 3 the highest.
15. When the nut is loosened, release
Trigger. Turn off air compressor
and disconnect the hose. If needed,
remove the nut from the socket.
16. To prevent accidents, turn off tool,
detach air supply, safely discharge
any residual air pressure in the tool,
and release the throttle and/or turn
the switch to its off position after use.
Clean external surfaces of the tool
with clean, dry cloth, and apply a thin
coat of tool oil. Then store the tool
indoors out of children’s reach.
USER-MAINTENANCE
INSTRUCTIONS
Procedures not specically
explained in this manual
must be performed only by a
qualied technician.
TO PREVENT
SERIOUS INJURY
FROM ACCIDENTAL
OPERATION: Turn off tool,
detach air supply, safely
discharge any residual air
pressure in tool, and release
Trigger before performing any
inspection, maintenance, or
cleaning procedures.
TO PREVENT SERIOUS
INJURY FROM TOOL
FAILURE: Do not use
damaged equipment. If
abnormal noise, vibration,
or leaking air occurs, have
problem corrected before
further use.
TO PREVENT EXPLOSION:
Lubricate tool only with
specied lubricants.
Lubricate air inlet using only
pneumatic tool oil. Lubricate
the internal mechanism using
only white lithium grease.
Other lubricants may damage
the mechanism and may be
highly ammable, causing an
explosion.
Cleaning, Maintenance, and
Lubrication
Note: These procedures are in addition to
the regular checks and maintenance
explained as part of the regular
operation of the air-operated tool.
1. Daily - Air Supply Maintenance:
Every day, perform maintenance
on the air supply according to
the component manufacturers’
instructions. The lubricator’s oil
level needs to be maintained and
the moisture lter must be regularly
drained. Performing routine
maintenance on the air supply will
allow the tool to operate more safely
and will also reduce wear on the tool.
2. Quarterly (every 3 months) -
Tool Disassembly, Cleaning,
and Inspection: Have the internal
mechanism cleaned, inspected, and
lubricated by a qualied technician.
3. Clean inlet bushing and air strainer
screen regularly.
4. Check if housing cap screws are
tight. If not, tighten them.
5. When storing, always store Impact
Wrench in clean, dry and safe
location out of reach of children).