Rolair 4090RK17 User manual

MODEL # 4090HK17, 4090RK17
SERIAL #__________________
INSTRUCTION MANUAL
606 South Lake Street > P.O. Box 346 > Hustisford, WI 53034-0346 > 920.349.3281 > fax [phone] > www.rolair.com

*For maximum performance and service life, we recommend using ROLAIR Premium
Quality Air Compressor Oil
3. The warranty on the motor will be NULL and VOID if a failure occurs and
inspection proves a current deficiency.
4. The PRESSURE SWITCH and/or pilot unloader valve are set at factory for
maximum efficiency. DO NOT alter setting. Adjusting either will VOID
the warranty.
5. Engine RMP’s (High – Low Settings) are factory set for maximum
efficiency. Adjusting RPM’s above factory specifications voids warranty.
6. ALWAYS shut off the engine’s fuel line before transporting a gas
powered air compressor. If left open, gas will seep past the needle/seat
in carburetor, mix with the oil in the engine’s crankcase, and foul out
the spark plug. Replacement of spark plug and oil change will not be
covered under warranty.
PLEASE NOTE: Refer to the enclosed engine owner’s manual for
additional operating information
Temp. 0 - 40° 40° & above
NON-DETERGENT
Straight Weight
Recommended
10 WT 30 WT
Extension Cord
Length
Motor
1/2 and 3/4 HP
Minimum Wire Size
Motor
1, 1-1/2 and 2 HP
Minimum Wire Size
Up to 25 Ft. 14 Ga. 12 Ga.
25-50 Ft. 12 Ga. 10 Ga.
50-100 Ft. 10 Ga. 8 Ga.
SPECIFICATIONS & GUIDELINES
*IMPORTANT:
READ ENCLOSED MANUALS BEFORE OPERATING YOUR COMPRESSOR
1. OIL TYPE TABLE
2. EXTENSION CORD TABLE

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PORTABLE AIR COMPRESSOR
OWNER’S MANUAL
WARNING
COMPRESSOR DISCHARGE AIR MAY CONTAIN HYDROCARBONS AND OTHER
CONTAMINANTS! DO NOT USE DISCHARGE AIR FOR BREATHING!
PARTS
Genuine ROLAIR replacement parts are sold nationwide through a network of authorized dealers and service
centers. Please contact the dealership where your air compressor was purchased or our factory Customer
Service Department if you need help troubleshooting, obtaining parts, or locating an authorized ROLAIR
service representative.
RECORD OF PERTINENT INFORMATION
Make a permanent record of the model and serial number of your new air compressor here. You’ll save time and
expense by including this reference information when requesting service or replacement parts.
Place & Date of Purchase Volts
Model HZ
Serial # HP
With the tank gauge at 0 PSI and air line(s) disconnected, close drain valve(s) and record the amount of time it takes
to build tank pressure on the space provided. Periodically test your air compressor against this pump-up time to
determine if it is operating correctly. If time test is considerably off, contact your local ROLAIR representative to
arrange service.
From 0 to ______*PSI From 0 to ______*PSI
Date Min Sec Date Min Sec
To order replacement parts: 1. Give compressor model number
2. Give compressor serial number
3. Name of part
4. Part number
5. Quantity required
606 South Lake Street > P.O. Box 346 > Hustisford, WI 53034-0346 > 920.349.3281 > fax [phone] > www.rolair.com

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TABLE OF CONTENTS
Introduction and Definitions of Safety Warnings------------------------------------------------------- 2
Safety Warnings – Risk of Asphyxiation & Bursting---------------------------------------------------- 3
Safety Warnings – Risk of Electrocution, Shock, Explosion, & Fire-------------------------------- 3
Safety Warnings – Risk of Moving Parts, Burns, & Lifting--------------------------------------------- 4
Safety Warnings – Risk of Propelled Objects, Unsafe Operation, and Damage---------------- 4
To Compressor or Property
Identification of System Controls--------------------------------------------------------------------------- 5-6
Pre-Start Checklist---------------------------------------------------------------------------------------------- 7
Operation---------------------------------------------------------------------------------------------------------- 8
Maintenance------------------------------------------------------------------------------------------------------ 9-10
Troubleshooting-------------------------------------------------------------------------------------------------- 11
Guarantee--------------------------------------------------------------------------------------------------------- 12
INTRODUCTION
Congratulations on the purchase of your new ROLAIR air compressor!
With over 50 years experience building ROLAIR air compressors specifically designed for the professional,
Associate Engineering Corporation has earned a reputation for providing a product unsurpassed in quality
and reliability. We are committed to continuing this tradition by analyzing and adapting to the changing
needs and rigorous demands of your industry. You can depend on ROLAIR because they are built to last.
This manual was compiled for the benefit of the operator. Do not use or allow anyone else to use your air
compressor until this manual is read and all safety/operating instructions are understood. By reading and
following the instructions contained in this manual, you can achieve years of trouble free service from your
new air compressor. If you have any additional safety or operating questions after reading this manual,
please contact your distributor or our customer service department. Do not remove or paint over any of
the warning decals attached to the compressor.
Definitions – Safety Warnings
Safety symbols are used throughout this manual to alert you to potentially hazardous situations. The
following definitions describe the level of severity for each signal word.
DANGER: Indicates an imminently hazardous situation which, if not avoided,
WILL result in death or serious injury.
WARNING: Indicates a potentially hazardous situation which, if not avoided,
COULD result in death or serious injury.
CAUTION: Indicates a potentially hazardous situation which, if not avoided,
MAY result in minor or moderate injury or damage to the air
compressor.

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Hazard Level Potential of Hazard How to Avoid Hazard
Risk of Asphyxiation
Serious injury or death may occur from
inhaling compressed air. The air stream may
contain carbon monoxide, toxic vapors, or
solid particles.
Never inhale compressed air directly from the
pump, receiver, or from a breathing device
connected to the air compressor.
Sprayed materials such as paint, stucco,
insecticides, solvents, etc. contain harmful
vapors and poisons that may cause serious
injury or death if inhaled.
Operate compressor only in a well-ventilated
area. Use a respirator device and follow the
manufacturer’s recommendations for their
spray equipment. Keep compressor at least
25 feet away from spray equipment.
Serious injury or death may occur if the
exhaust from gas-powered small engines is
inhaled. Engine exhaust fumes contain
poisonous, carbon monoxide which is odorless
and colorless.
Operate gas-powered compressors only in a
well-ventilated area. Avoid inhaling engine
exhaust fumes, and never run a small gas-
powered engine in a closed building or
confined area without adequate ventilation.
Risk of Bursting
Serious injury or death may occur from an air
tank explosion if the air tanks are not properly
maintained or if modifications, alterations or
repairs are attempted to the air receivers.
Drain air tanks daily or after each use. Never
drill into, weld, patch or modify the air tanks.
If a leak develops, replace the tank
immediately or replace the entire compressor.
Serious injury or death may occur if
modifications are made to the pilot unloader
valve, pressure switch, safety relief valve or
other components that control the tank
pressure.
Never make adjustments to the components
that control tank pressure. Do not make
alterations to the factory operating pressure
settings. Check operation of the safety valve
on a regular basis and never operate without a
factory approved safety valve.
Serious injury may occur if accessories or
attachments are operated above the
manufacturer’s recommended pressure
ratings, causing them to explode or fly apart.
Do not use air tools or attachments before
reading the owner’s manual to determine the
maximum pressure recommendations. Never
exceed the manufacturer’s maximum
allowable pressure ratings. Do not use
compressor to inflate small low pressure
objects such as toys.
Risk of Electrocution or
Electrical Shock
Serious injury or death could occur if the air
compressor is not properly grounded.
Always plug compressor into a properly
grounded outlet which provides correct
voltage, proper grounding and adequate fuse
protection.
Electrical shock may occur if compressor is
not properly operated.
Never operate air compressor in wet
conditions or outdoors when it’s raining. Do
not allow electric cords to lay in water. Do not
operate with damaged power cord or with
protective electrical covers removed. Do not
touch plug with wet hands. Do not pull on
electric cord to disconnect from the outlet.
Serious injury or death may occur if electrical
repairs are attempted by unqualified
personnel.
Any electrical repairs or wiring performed on
this compressor should only be performed by
authorized service personnel in accordance
with the National and Local Electric Codes.
Risk of Explosion or Fire
Serious injury or death may result from normal
electrical sparks that occur within the motor
and/or pressure switch.
Always operate compressor in a well-
ventilated area free of combustible materials,
gasoline, flammable solvents or vapors.
Always locate compressor at least 20 feet
away from work area if spraying flammable
materials.
Serious injury may occur if a fire is caused by
overheating due to inadequate ventilation or
restrictions to any of the compressors
ventilation openings.
Never place objects against or on top of an air
compressor. Always operate air compressor
at least 18” away from any wall or obstruction.
Always operate in a clean, dry and well-
ventilated area.
Serious injury or death may occur from a fire
or explosion if spilled gas or vapors come in
contact with hot engine parts and ignite.
Never attempt to fill the gas tank while the
engine is hot or running. Add fuel outdoors in
a well-ventilated area. Do not fill gas tank near
lit cigarettes or near other sources of ignition.
SAFETY WARNINGS
WARNING
The engine exhaust from this product
contains chemicals known to the State
of California to cause cancer, birth
defects or other reproductive harm.
READ AND UNDERSTAND ALL SAFETY WARNINGS BEFORE USING AIR COMPRESSOR

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SAFETY WARNINGS (con’t)
Risk from Moving Parts
Serious injury may occur from moving parts
such as belts, pulleys, flywheels or fans if they
came in contact with you or your clothing.
Never operate the air compressor without
protective belt guards installed. Replace
damaged protective covers or guards
immediately.
An electric air compressor with automatic
controls can restart at any time and cause
bodily injury when least expected.
Always unplug air compressor and drain air
tanks completely before attempting any
repairs or performing maintenance. Never
allow children or adolescents to operate air
compressor.
Serious injury may occur if repairs are
attempted with damaged, missing or removed
protective guards, shrouds or missing covers.
All repairs to the air compressor should be
made only by authorized or trained service
personnel.
Risk of Burn
Serious burn injuries could occur from
touching exposed metal parts such as the
compressor head, copper/braided discharge
lines and engine exhaust muffler during
operation, and even after compressor is shut
down for sometime.
Never touch any of the exposed metal parts
during operation and for an extended period of
time after the air compressor has shut down.
Do not attempt maintenance on the unit until
it has been allowed to completely cool.
Risk of Injury from Lifting
Serious injury can result from attempting to lift
an object that is too heavy.
Always obtain assistance from others before
attempting to lift any object that is too heavy
for one person.
Flying Objects
Serious injury may occur from loose debris
being propelled at high speeds from the
compressed air stream.
Always wear OSHA required “287” safety
glasses to protect the eyes during operation of
the air compressor. Never point the air stream
or tools at any point of your body, other
people or animals.
Always turn off the air compressor and drain
tank pressure completely before attempting
maintenance or attaching air tools.
Warning
Risk of Unsafe Operation
Serious injury or death may occur to you or
others if air compressor is used in an unsafe
manner.
Review and understand all instructions and
warnings in your owner’s manual. Know how
to stop the air compressor. Do not operate
until you are thoroughly familiar with all of the
controls. Do not operate the compressor if
fatigued or under the influence of alcohol or
drugs. Stay alert while operating the
compressor and pay close attention to the
task at hand.
Caution
Risk of Damage to
Air Compressor or Property
Failure to transport or operate the air
compressor properly may result in major
repair expenses. Oil leaks will damage carpets,
painted surfaces, flooring and other items.
Check oil levels daily and maintain proper oil
levels. Always run compressor in a level,
secure position that keeps it from tipping or
falling during use. Do not operate without an
air filter or in a corrosive environment.
Always transport in a level position and use
protective mats to keep truck beds clean, etc.
Check drain bolts regularly and do not overfill
machinery with oil.
Please note that this product may not be equipped with a spark arresting muffler. If the compressor is operated
around flammable materials or agricultural crops, brush, forests, and grasslands an approved spark arrestor must be
installed, maintained and in good working order. An approved spark arrestor is legally required in the State of
California under sections 4442 and 4443 of the California Public Resources Code Statute section 130050.
This product contains chemicals, including lead, known to the state of California to cause cancer, birth defects, and
other reproductive harm. Always wash hands after handling this product.

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SYSTEM CONTROLS
(1) SAFETY-RELIEF VALVE Every ROLAIR air compressor is equipped with a safety-relief valve which is designed to discharge tank
pressure at a predetermined setting when a systems failure occurs. Check the safety valve periodically by pulling on the ring only
when the tank pressure is completely drained. The spring loaded valve should move freely within the safety valve body. An
inoperable safety valve could allow an excessive amount of tank pressure to build causing the air tank to catastrophically rupture
or explode.
Do not tamper with or attempt to eliminate the safety relief valve.
(2) MANUAL OVERLOAD / MOTOR RESET Every ROLAIR electric air compressor is built with manual overload protection. If the motor
overheats, the overload sensor will trip the reset button to protect the motor. If this occurs, please allow the motor to cool for
approximately five minutes. Locate and push in the reset button. The use of an undersized or excessive length of extension cord
may be the cause of overheating. Re-evaluate the power source and gauge/length of extension cord being used. (Refer to chart
on page 8)
(3) PRESSURE SWITCH Most electric air compressors are operated by the use of a pressure switch. Always make sure the lever
is in the “Off” position before plugging in the power cord. By moving the lever to the “On/Auto” position, the compressor will start
and stop automatically within the settings of the pressure switch which are typically 105 – 130 PSI. Do not attempt to stop the
compressor by unplugging the power cord. To stop, simply move the lever to the “Off” position. The lever operates a relief valve
that dumps off head pressure and allows the compressor to restart without load the next time it is used.
(4) REGULATOR – WORKING PRESSURE To adjust the output/line pressure, simply lift up on the regulator adjustment knob and rotate
clockwise to increase working pressure or counterclockwise to decrease. Push adjustment knob back down to lock in setting.
Never exceed the manufacturer’s maximum allowable pressure rating of the tool being used or item being inflated.
(5) PRESSURE GAUGE(S) Typically, most compressors are designed with a gauge to measure tank or storage pressure and
another gauge attached to the regulator that indicates output or working pressure.
(6) DRAIN VALVE(S) One or more drain valves are installed to allow moisture to be drained on a daily basis from the compressor
storage tank(s). Open drains carefully and slowly to prevent scale, rust, or debris from becoming expelled at a high rate of speed.
(7) AIR INTAKE FILTER Air intake filters are installed to prevent foreign matter from entering the engine or compressor pump.
Check intake elements on a regular basis and either clean or replace as needed. Warm soapy water or low compressed air may
be used to clean the elements. Check intake canisters or elbow components for cracks or broken seals and replace if structural
problems are found.

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SYSTEM CONTROLS
(con’t)
(8) PILOT-UNLOADER VALVE A pilot-unloader valve is used on all gas-powered units and can be used on electric air compressors
to operate in a continuous manner. When the storage tank reaches the top pressure setting of the pilot valve, the air being
compressed is discharged to atmosphere instead of into the storage tank. When the tank pressure drops to the low pressure
setting of the pilot valve, the compressed air will be redirected to the air tank. Do not attempt to replace the pilot valve without
first draining the tank pressure completely. See Figure 3 for adjustment and fine-tuning instructions. Do not adjust above the
following factory recommendations.
Classification Pressure Setting
Direct Drive Compressor 105-130 PSI
I-Stage Compressor 110-135 PSI
II-Stage Compressor 130-150 PSI
(9) SIGHT GAUGE/DIPSTICK Prior to daily operation, make a habit of checking the oil level of the compressor pump and engine (if
compressor is gas powered). Every direct-drive hand-carry air compressor has a dipstick to help check and maintain the proper oil
level. The dipstick also functions as a crankcase vent. Never operate a direct-drive unit without the factory supplied dipstick. Our
belt-driven air compressors are equipped with a sight gauge to make the daily task of checking the oil level easier. Always
maintain the oil level to read 2/3 full on the sight gauge.
(10) CHECK VALVE Every ROLAIR air compressor is built with a check valve to seal off and maintain tank pressure after the top
end pressure setting of pilot valve or pressure switch is reached. The check valve works in conjunction with the pressure switch
relief valve to provide a
loadless start for the compressor system. A quick burst of air escaping from the pressure switch relief
valve after an electric unit reaches top end indicates the check valve is working properly. If the compressor has a mysterious leak
after stopping that cannot be traced elsewhere, the check valve may require servicing/replacing.
(11) BREATHER/OIL FILL PLUG All reciprocating air compressor pumps are built with a crankcase vent to relieve the pressure
that is created by the downward movement of the piston in the pump cylinder. Our direct-drive air compressors vent the
crankcase pressure through special ports in the dipstick. Our belt-drive units vent through the oil-fill plug. Never operate the air
compressor without the dipstick or oil-fill plug.
(12) AUTOMATIC-IDLE CONTROL Every ROLAIR gas-powered air compressor is built with an engine idle control kit that
automatically decreases the engine speed when the top end pressure setting of the pilot unloader valve is reached. The top RPM
setting of the engine is factory set for maximum performance and service life. Do not alter the factory top RPM setting. The engine
idle speed is factory set and controlled by a black plastic Philips head screw on the carburetor. A slight increase to the idle speed
setting may be required when operating in colder temperatures. Turn screw clockwise in 1/4 turn increments to increase the idle
speed. If the idle speed setting is too low, premature fouling of spark plug will occur.
(13) COLD-START VALVE Most ROLAIR direct-drive air compressors are built with an automatic cold-start valve that allows the
motor/pump to warm up before being subjected to tank pressure. Our belt-driven portable units have a manual drain valve
installed on the pump aftercooler to assist with cold weather starting. Open drain valve and allow the motor and pump to run
unloaded for a minute to warm up. Close the drain and repeat the procedure if the motor or engine continue to struggle.
(14) SCHMIDT BELT-TIGHTENING DEVICE (FOR GAS UNITS ONLY) Every ROLAIR gas-powered belt-driven portable air compressor
has a unique system for maintaining proper belt tension. Simply loosen the 1/2” locknuts (only until washers beneath spin freely)
that secure the engine and rotate the fine thread bolt located on the wheel end of the base plate clockwise until the desired belt
tension is achieved. (See drawing in section on operating instructions for proper tension) Re-tighten 1/2” locknuts to secure engine
and maintain desired belt tension setting.
(15) VIBRATION DAMPENER(S) The rubber pads installed beneath every portable ROLAIR tank assembly are very important to the
proper operation of the air compressor. They provide protection from vibration that left unchecked could cause damage to many
system components.
(16) ENGINE KILL SWITCH A kill switch is installed to easily stop the engine. Do not attempt to move the throttle lever (as
described in the Honda owner’s manual) when stopping the engine. The engine throttle lever is factory set and locked down at a
top RPM setting that will provide maximum performance and service life for the complete air compressor system. The kill switch
must be moved to the “On” position prior to pulling the recoil rope assembly to start the engine.
(17) ENGINE CHOKE Moving the choke lever completely to the left (closed position) will help start a cold engine. Also see
instructions for cold-start valve (Item #13). After start up, the choke lever must be moved completely to the right (open position)
for the engine to operate properly. Fouling of spark plug and excessive internal carbon build up will occur if engine is operated
with choke lever even partially closed.
(18) FUEL SHUT-OFF VALVE The fuel shut-off valve should only be moved to the “Open” position (completely to the right) when
the engine is being operated. Always stop the flow of fuel by moving the shut-off valve completely to the left when the engine is
not being operated. Do not move or transport the air compressor with the fuel valve in the open position.

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PRE-START CHECKLIST
Read the owner’s manual thoroughly. Make sure that you completely understand all of the safety warnings,
system controls and instructions provided before attempting to operate this air compressor. Every effort has been
made to provide you with the information needed to obtain many years of reliable and trouble-free service out of
your new air compressor. It is your responsibility to operate the air compressor properly. To obtain the longest
possible service life from your air compressor you must always keep the following instructions in mind.
1. ALWAYS OPERATE THE COMPRESSOR IN A LEVEL POSITION
All splash-lubricated pumps have a dipper on the bottom of the connecting rod that must remain submerged in
the oil bath. Operation at more than a 10 degree angle will cause the pump to seize and void the product
warranty
2. OPERATE IN A CLEAN, DRY AND WELL VENTILATED AREA
Allow at least 18” behind the belt guard for proper cooling of pump from flywheel blast. Do not operate in the rain
or in areas of standing water. Never operate in an area where other gases, fumes or vapors are present which
may become explosive when compressed. Do not operate compressor in an enclosed area.
3. CHECK OIL LEVEL DAILY AND CHANGE AT REGULAR INTERVALS
Refer to the maintenance section of this owner’s manual for the correct type/weight of oil to use and how often
the oil should be changed. Check oil levels daily.
4. INSPECT/CLEAN/CHANGE INTAKE ELEMENTS ON A REGULAR BASIS
The ingestion of dirt into the pump and engine is the primary cause of premature wear. Pay special attention to
the intake filters. Check intake filters daily.
5. USE LONGER PROPERLY SIZED AIR HOSE RATHER THAN EXTENSION CORDS
If an extension cord must be used, please refer to the chart below for the proper gauge and maximum length that
can be used. The use of inadequately sized air hose will also lead to frictional pressure drops that could affect the
proper performance of your air tools.
6. DO NOT USE A GENERATOR AS THE POWER SOURCE
Air compressors use inductive motors that require 3-5 times the full-load amp draw to properly start. Most
generators will not provide the wattage needed to properly start this type of electric motor.
7. CHECK TENSION OF BOLTS, BELTS, AND HARDWARE ON A REGULAR BASIS
Operation of any equipment with loose bolts and/or fittings will lead to excessive vibration
and the premature failure of the compressor system control components.
8. MAINTAIN RUBBER VIBRATION PADS
Excessive vibration is a major cause of premature compressor failure. Always maintain the rubber vibration pads
located beneath tank assembly. Operation without them will void your warranty.
9. DRAIN MOISTURE FROM AIR TANKS DAILY
Water is a natural byproduct of compressed air. Drain air tank(s) after each use to combat internal tank corrosion.
Keep drain valve(s) closed if storing compressor for any length of time.
ELECTRIC EXTENSION CORD TABLE
Minimum Wire Size
Extension
Cord Length
Motor
1/2 and 3/4 HP
Motor
1, 1-1/2, and 2 HP
Up to 25 ft. 14 Ga. 12 Ga.
25 – 50 ft. 12 Ga. 10 Ga.
50 – 100 ft. 10 Ga. 8 Ga.
10. DO NOT ALTER FACTORY RPM SETTINGS ON GAS-POWERED COMPRESSORS. Engine throttle arm is factory set
and locked into position at RPMs that will provide maximum performance, fuel consumption and service life.
Alterations to this setting will void your warranty.

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OPERATION
WARNING – Your safety and the wellbeing of others during the operation of every ROLAIR compressor is our main
concern. Do not operate or permit anyone else to operate your air compressor until the information contained in this
manual is read and completely understood. Please contact your distributor or our customer service department if you
have any questions on the proper use of your air compressor.
DIRECT-DRIVE ELECTRIC
Establish that the air compressor is ready to operate by reviewing the topics and information provided in the “Pre-
Start Checklist” section of this manual. Slowly open tank drain to remove any condensate that has accumulated and
keep drain open for a few seconds after starting to warm up motor/pump assembly. Make sure the pressure switch
lever is in the “Off” position before plugging power cord into a properly grounded outlet. Move pressure switch lever
to the “On/Auto” position to build and automatically maintain top end tank pressure setting. Rotate regulator
adjustment knob counterclockwise until the gauge attached reads 0 PSI before attaching air hose and accessory. Set
working pressure by rotating regulator adjustment knob clockwise and lock in working pressure according to
specifications provided by the tool manufacturer. Always use the pressure switch “On(Auto)/Off” lever to start or stop
the air compressor. Never stop the compressor by unplugging it from the power source. Store compressor in a
warm/dry location and perform maintenance as indicated in manual.
BELT-DRIVE ELECTRIC
START/STOP OPERATION:
Follow same procedures described above for use of direct-drive electric
compressors. Open drain valve located on pump aftercooler for cold
starting purposes. An electric belt-driven motor should not be subjected to
more than 15 starts per hour. Consult your dealer or any authorized
ROLAIR service center for information on a conversion kit if you experience
nuisance tripping of the motor overload due to an excessive amount of
motor starts per hour.
CONSTANT-SPEED OPERATION:
Constant speed or continuous-running operation should be used during
periods of heavy use to extend motor life and prevent overheating. If your
machine is built to only operate continuously, special care must be taken
to safely start and stop the machine. Always shut off the power to the
electrical outlet at the main breaker or optional on/off switch before
plugging in or unplugging the power cord. We also highly recommend
complete draining of storage tank(s) and opening of aftercooler drain valve prior to starting, especially when
operating in cold temperatures. Never stop the compressor by pulling the plug from the outlet. Use the breaker or
optional on/off switch to shut off the power to the outlet first.
DUAL-CONTROL OPERATION:
Dual controls allow an easy transition between start/stop and continuous-running operation. See figure 1 for
instructions to switch operation from start/stop to constant speed. Always flip the lever on the pressure switch to the
“off” position before plugging in or unplugging the power cord.
GAS POWERED
Refer to item numbers 12, 16, 17 & 18 in the “System Controls” section of this manual for information on the engine
automatic idle control, kill switch, choke and fuel shut-off valve. Also note the engine throttle arm is locked into a top
RPM setting that will provide maximum service life and does not need to be moved to start or stop the machine.
Additional instructions can be found in the engine owner’s manual. Use the drain valve located on the pump
aftercooler or intercooler for cold-starting purposes. Take additional care to keep dirt/debris from entering the fuel
tank or obstructing the air flow through the engine or past the pump. Make sure the air flow to the regulator is
completely closed (gauge attached reads 0 PSI) before attaching air hose and accessory. A slight
hissing noise caused
by the air flow being directed to atmosphere during engine idle is normal. Store compressor in a warm/dry location
and perform maintenance as indicated in your manuals.

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MAINTENANCE
Your new air compressor represents the finest engineering and construction available. Even the best
machinery requires periodic maintenance. Please stick to the maintenance schedule and consider the suggestions
that follow to keep your compressor in peak condition.
NOTE: Always unplug or shut down your compressor and drain the air tanks completely before attempting any
type of maintenance. Wait for compressor to cool before servicing.
IMPORTANT: Replace the oil after the first 50 hours of operation.
MAINTENANCE HINTS: 1) Use a soap/water solution to check for air leaks.
2) Never clean filters with a flammable solvent.
3) Retorque head bolts only after pump has cooled.
4) Move motor 1/4" and roll belts back on to increase
belt tension on electric units.
5) Never weld on air tank(s).
6) Use heat to loosen Loctite seal on drain valves, engine
pulleys, and flywheels before attempting to remove.
OIL TYPE TABLE
Temperature 0-40° 40° & Above
NON-DETERGENT
–
Straight Weight 10WT* 30WT*
*For maximum performance and service life, we recommend using ROLAIR Premium Quality compressor oil.
MAINTENANCE SCHEDULE
Recommendation Daily Weekly Monthly Quarterly
Check Oil Level X
Drain Moisture from Tank(s) X
Inspect Air Filter(s) X
Check for Unusual Noise or Vibration X
Inspect Belt Guard X
Check for Air or Oil Leaks X
Clean Exterior of Air Compressor X
Check Condition of Vibration Pads X
Tighten/Retorque Bolts X
Check Belt Tension X
Check Operation of Safety Valve X
Change Compressor Oil X
Clean/Change Air Filter X
Perform Pump Up Time Test X
Check Operation of System Controls X
Check Air Tanks for Dents/Leaks X
LUBRICATION
Prior to each use, make a habit of checking the pump oil
level. Most direct-drive air compressors have a dipstick with
casting marks that indicate the minimum and maximum
acceptable levels of oil. Our belt-driven pumps have a sight gauge,
located on the outside of the crankcase, to make the task even
easier. Always maintain the oil level at the maximum mark on the
dipstick or to 2/3 full in the sight gauge
Do not operate the pump with an inadequate or excessive
amount of oil. The cost of failures which occur due to incorrect oil
levels will not be covered under warranty.
DO NOT USE A DETERGENT OIL!
NOTE: Unit must be level when in operation

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DRIVE PULLEYS
TORQUE CHART (INCH/LB)
Pump Type Direct Drive K12 K17 K18 K24 K28 K30
Head Bolts 96 243 243 243 243 347 347
Cylinder Bolts 120 182 182 182 182 330 330
Bearing-Carrier Bolts N/A 130 130 130 130 130 130
Connecting-Rod Bolts N/A 121.5 121.5 121.5 121.5 121.5 173.6
Flywheel N/A 243 382 382 382 477 477
Determine pump type using suffix of Model number (Example: 4090HK17 uses K17 pump)
PILOT VALVE ADJUSTMENT
RESETTING DIFFERENTIAL (2)
Make sure the top toggle lever is positioned as shown. (See Figure 3). Loosen locknut (1) by
turning counterclockwise several full turns. Gently turn differential setting (2) clockwise only
until the internal rod makes contact with the steel ball inside. After making contact, turn
differential (2) counterclockwise 1/4 turn. Secure position by tightening locknut (1) and
proceed to top end setting.
TOP END SETTING (4)
Loosen locknut (3) by turning counterclockwise several full turns. (4) is the top end setting.
Turning (4) clockwise will increase the top end pressure setting. Turning counterclockwise
will decrease the top end pressure setting. Begin at a low setting by turning
counterclockwise one full turn. Proceed to fine tuning instructions.
FINE TUNING INSTRUCTIONS
Start engine/motor and observe tank pressure gauge. As tank pressure approaches 100-130
P.S.I.G., the pilot valve should begin unloading at felt muffler and cause gas engine to slow
down to idle speed. If pilot valve does not unload as tank pressure approaches 130 P.S.I.G.,
slowly turn top end setting (4) counterclockwise until pilot starts to unload prematurely (at
100 P.S.I.G.), turn top end setting (4) clockwise in 1/4 turn increments, tap down on the
internal rod at toggle attachment and repeat until desired top end setting is reached. If pilot
valve begins to rifle (sputter), fine tune differential setting (2) 1/16 turn in either direction
until rifling stops. After fine tuning, secure setting by turning locknuts (1 & 3) clockwise until
tight. Hold setting (2 & 4) in place while turning locknuts to secure.
SCHMIDT BELT-TIGHTENING DEVICE
(FOR GAS UNITS ONLY)
To tighten belt tension, proceed as follows:
1. Loosen locknuts for engine hold-down bolts only until washers beneath
spin freely.
2. Rotate 1/2” adjusting bolt clockwise until desired tension is reached. (See
Figure 4).
3. Retighten locknuts to secure engine.
Drive pulleys must be properly aligned and drive belt
tension set to specification. Improper pulley alignment
and belt tension can cause motor overloading, excessive
vibration and premature belt and/or bearing failure.
(See Figure 5).
GASOLINE ENGINE RPM SETTINGS
Model Top RPM Idle RPM Pump RPM
4090 Series 2950 1900 1025
1040 & 2040 Series 2775 1900 1175
6590 Series 3150 1900 1125
8422 & 8230 Series 3000 1900 900
NOTE: Engine RPM’s (High – Low Settings) are factory set for maximum efficiency. Adjusting RPM’s above
factory specification will void the warranty.

- 11 -
TROUBLESHOOTING
WARNING - Make sure you completely understand all of the safety warnings and operation of each system
control component before attempting any maintenance or repair. Always drain the tank pressure completely, make
sure the power cord is unplugged, and unit has time to cool before performing any maintenance or service
operations.
PROBLEM CAUSE SOLUTION
Pump is slow to build tank pressure
Loose/slipping belt Adjust belt tension
Excessive leaks in system Correct air leaks
Blown gasket Replace head gaskets
Broken reed valve Replace reed valves
Obstructed intake filter Clean or replace intake element
Leaking regulator Replace regulator
Defective pilot valve Replace pilot valve
Excessive oil consumption
Too much oil in crankcase Drain to proper level
Improper weight of oil Replace with proper oil
Obstructed crankcase vent Replace dipstick or oil fill
plug/crankcase vent
Dirty/plugged intake filter Clean/replace intake filter
Worn piston rings Take unit in for service
Scored cylinder Take unit in for service
Knocking noise
Loose pulley or flywheel Tighten appropriate parts
Loose belts Adjust belt tension
Internal pump problem Take unit in for service
Overheating compressor
Poor ventilation Relocate compressor
Improper pump rotation Contact an electrician
Internal pump problem Take unit in for service
Electric motor dead,
will not even hum
Thermal overload tripped Locate and push reset button
Reset physically broken Replace overload/reset
Loose motor leads or electrical
connection
Locate and correct loose electrical
connection(s)
Short in power cord Replace power cord
Motor trips overload/reset button
Motor is starting/stopping
excessively
Install constant speed or dual control
kit
Overload is defective/wea
k
Replace overload
Improper gauge of extension cord Use longer lengths of air hose or
heavier cord
Stripped or poorly tightened motor
thru bolts
Retighten or replace stripped thru
bolts
Cracks in end bell or housing Take unit in for service
Gasoline engine is hard to start
Fouled, incorrect, or improperly
gapped spark plug
Install proper spark plug after
gapping to factory specs
Improper engine oil level Fill to top of threads for oil plug
Improper weight of pump or engine
oil
Change to proper weight of oil for
operating temperature
Improper or old gas Take unit in for service

- 12 -
Guarantee
Associate Engineering Corporation warrants that all ROLAIR compressors will be free of defects in
material and workmanship for a period of twelve months from the date of initial retail purchase, or
eighteen months from the date of manufacture, whichever may occur first.
Should any failure to conform to this warranty be reported to the company within said period, the
company shall, upon purchaser shipping the compressor to our plant transportation prepaid, correct
such nonconformity by suitable repair or, at its option, furnish a replacement part F.O.B. our plant.
Associate Engineering Corporation shall not be liable for any unauthorized repairs, replacements,
adjustments to the compressors, or the costs of labor performed by the purchaser.
This warranty is expressly in lieu of all other warranties expressed, implied or statutory (including,
but not limited to, warranties of merchantability and fitness for purpose) and of any other
obligations, and/or liabilities on the part of Associate Engineering Corporation. Associate
Engineering Corporation neither assumes nor authorizes any other person to assume for it any
other obligations or liability in connection with or with respect to any compressor.
Associate Engineering Corporation shall in no event be liable neither for any consequential, incidental
or special damages nor for the improper selection of any compressor for a particular application.
Quality
Associate Engineering Corporation is devoted to continual quality control and thorough
research of the products we build. It is our creed to give you, the user, all of the
experience and engineering available in the production of every piece of equipment we
produce.
Our line covers the complete needs of today’s varied air requirements. Rely on ROLAIR for
all the newest and finest features that are available for the modern compressor.
606 South Lake Street > P.O. Box 346 > Hustisford, WI 53034-0346 > 920.349.3281 > fax [phone] > www.rolair.com

8/11
Schem
# Description Part # Qty.
Schem
# Description Part # Qty.
1 Twin Cylinder Pump with
Flywheel PMP12K17CH 1
24 Drain Valve 132BV 2
25 Twin Tank Assembly TNKASY4090K17 1
Twin Cylinder Pump less
Flywheel PMP12K17CHLF 1
26 Rubber Foot 219 4
27 Cotter Pin 181A 2
2A Gasket 30501490CH 1 28 Axle 181 1
2B O-Ring 30502510CH 1 29 Fully-Pneumatic Tire with Sealant WLS30SEAL 1
3A Aftercooler 32901460CH 1 30 Pulley PUAK44X0750 1
3B Aftercooler - O-Ring Style Use 3290146ACH 1 31 Belt Guard Cover BG9145 1
4 Brass Elbow 145D 1 32 Belt Guard Base BG9140B 1
5 Braided Discharge Tube 145F 1 33 Belt BT4L510 1
6 Drain Valve 132 1 34 Flywheel 31007280CH 1
7 Check Valve CV4X4TA 1 35 Silencer/Filter Assembly FS14050 1
8 Brass Elbow BREL0250X0125H16 2 Filter Element – Replacement for
Above 431 1
9 Hose Clamp 177 2
10 1/4” Nylon Tube – 14.4” 178D 1.2’ 36 Honda Engine ENG05HO1 1
Brass Nut BRNT0250 2 37 Brass Elbow BREL0250X012539 1
Brass Sleeve BRSL0250 2 38 Throttle Control Kit 192EGX160K1QX 1
Brass Ring BRRG0250 2 39 Gauge GA0250200GC 1
11 Pilot Unloader Valve 131B 1 42 Belt Tightener/Mounting Kit SBT5HP-ANGLE* 1
Felt Muffler 131BM 1 43 Screw MIS10008 4
Retainer Ring 131BR 1 44 Bolt 37302530CH 2
12 Nipple BLNP0250X1500 1 45 Bolt MIS10094 5
13 Aluminum Block Manifold 154 1 46 Bolt MIS10022 2
14 Safety Relief Valve SRV0250N165 1 Lock Washer MIS10099 2
15 Nipple BLNP0500X1500 1 Washer MIS10108 2
16 Quick Disconnect 309A 1 (Accessories)
17 Accessory Bracket 210 1 47 Lubricator LUB0375 1
18 Brass Coupler BRCP0375X0375H12 2 48 Regulator REG0375 1
19 Hose Clamp 177A 2 49 Filter (Water Trap) FIL0375 1
20 3/8” Rubber Hose – 16” 178A 1.34’ 50 Accessory Bracket 210 1
21 Cap BLCA0250 1 51 Nipple BLNP0375X1500 3
22 1/4” Rubber Hose – 36” 178 3’ 52 Brass Coupler BRCP0375X0375H12 1
23 Handle Grip 328 2 53 Gauge GA0250200GC 1
*For units built prior to February 2005, order SBT5HP-SQUARE.
PARTS LIST FOR MODEL 4090HK17
606 South Lake Street > P.O. Box 346 > Hustisford, WI 53034-0346 > 920.349.3281 > fax [phone] > www.rolair.com

PARTS LIST FOR PMP12K17
Description Part # Qty.
Crankshaft 30201000CH 1
Bearing 30300030CH 2
Oil Seal 30300040CH 1
Bearing Carrier 30400830CH 1
Bearing Carrier 30400890CH 1
Gasket 30500130CH 1
Gasket 30500150CH 2
Gasket 30501090CH 1
Gasket 30501100CH 1
Gasket 30501110CH 1
Gasket 30501120CH 1
Gasket 30501490CH 1
O-Ring 30509290CH 1
Flywheel 31007280CH 1
Bearing Shell 31100210CH 2
Bushing* 31100240CH 2
Connecting Rod w/Upper Bushing 31100750CH 2
Connecting Rod Assembly 31100750CH1 2
Piston Pin 31200260CH 2
Piston 31200270CH 2
Ring 31200280CH 2
Ring 31200290CH 2
Ring 31200300CH 2
Head 31301170CH 1
Cylinder 31601010CH 1
Valve 32700350CH 4
Valve Plate 32701030CH 2
Aftercooler 32901460CH 1
Crankcase 33101160CH 1
Sight Gauge 36500140CH 1
3/8” Breather/Oil Fill Plug 36507050CH 1
Bolt 37300250CH 4
Bolt 37300990CH 6
Bolt 37301140CH 14
Bolt 37302530CH 2
Nut 37400220CH 4
Nut 37400720CH 1
Washer 37500310CH 4
Washer 37500400CH 6
Washer 37500730CH 1
Washer 37508130CH 14
Snap Ring 37600230CH 4
Filter Element 431 1
Plug BLSQPL0250 1
Silencer/Filter Assembly FS14050 1
Ring Set K17RINGS 1
Gasket Set K17GASKETS 1
Valve Plate Assembly (Valve plates, reeds & upper three gaskets) 1700VK17 1
Piston Assembly (Piston, rings, piston pin & snap rings) 1700PK17 2
AFTERCOOLER PARTS STARTING 2/00
O-Ring – Aftercooler 30502510CH 1
Aftercooler 3290146ACH 1
*BUSHING IS NOT MACHINED TO FIT PISTON PIN IF ORDERED SEPARATE FROM CONNECTING ROD.
606 South Lake Street > P.O. Box 346 > Hustisford, WI 53034-0346 > 9
920.349.3281 >
fax [phone] >
>www.rolair.com
5/09