ROLAIR 4090HMK103 Portable Air Compressor Instruction Manual

Introduction

Thank you for purchasing a ROLAIR!

If after reading this manual you have any questions whatsoever on the proper installation, operation, or maintenance of your air compressor please feel free to contact our Customer Service Department at 1-800-310-3573.

We would love to hear from you!

Manufacturer: Associate Engineering Corporation

Address: 606 South Lake Street > P.O. Box 346 > Hustisford, WI 53034-0346

Contact: 920.349.3281 | Fax: 920.349.8861 | www.rolair.com

Owner's Manual Overview

This manual provides comprehensive information for the ROLAIR Portable Air Compressor, Model 4090HMK103.

Parts Information

Genuine ROLAIR replacement parts are available nationwide through authorized dealers and service centers. To order parts, please provide:

• Compressor model number
• Compressor serial number
• Name of part
• Part number
• Quantity required

Record of Pertinent Information

Make a permanent record of your compressor's model and serial number here for future reference when requesting service or parts.

Pump-Up Time Test: With the tank gauge at 0 PSI and air line(s) disconnected, close drain valve(s) and record the time it takes to build tank pressure. Periodically re-test to ensure correct operation.

Introduction & Safety Warnings

Congratulations on your purchase of a ROLAIR air compressor! With over 50 years of experience, ROLAIR is known for quality and reliability.

This manual is for the operator's benefit. Read and understand all instructions before use. Failure to do so could result in serious injury or death.

Definitions of Safety Warnings

❗ 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.

ℹ️ CAUTION: Indicates a potentially hazardous situation which, if not avoided, MAY result in minor or moderate injury or damage to the air compressor, or other property.

General Safety Warnings

⚠️ WARNING: Do not start, operate, or service this machine until you read and fully understand the owner's manual. Failure to do so could result in death or serious injury. Call 1-800-310-3573 with questions.

⚠️ WARNING: CONTAINS LEAD. May be harmful if eaten or chewed. May generate dust containing lead. Wash hands after use. Keep out of reach of children.

⚠️ WARNING: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, visit www.P65Warnings.ca.gov.

SAVE THESE INSTRUCTIONS!

Specific Hazards and Precautions

❗ DANGER: RISK OF EXPLOSION OR FIRE

What Can Happen:

• Electrical components within the motor and pressure switch will spark. If sparks contact flammable vapors, they may ignite, causing fire or explosion.
• Inadequate ventilation or restricted openings can cause serious overheating and fire.
• Unattended compressors with leaks can start unexpectedly, leading to overheating, fire, and injury or property damage.
• Spilled gas or vapors contacting hot engine parts, cigarettes, or other ignition sources can cause fire.

How to Avoid It:

• Operate in a well-ventilated area away from flammable vapors.
• Locate compressor at least 20 ft. (6.1m) away from work areas if spraying flammable materials.
• Store flammable materials securely away from the compressor.
• Never place objects against or on top of the compressor.
• Operate compressor at least 18" away from walls or obstructions.
• Operate in a clean, dry, and well-ventilated area.
• Always remain in attendance while the compressor is operating.
• Turn off and unplug the compressor when not in use.
• 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 other ignition sources.

❗ DANGER: RISK TO BREATHING (ASPHYXIATION)

What Can Happen:

• Compressed air is not safe for breathing; it may contain carbon monoxide, toxic vapors, or solid particles. Inhaling it can cause serious injury or death.
• Sprayed materials (paint, stucco, solvents) may contain harmful vapors.
• Gas engine exhaust fumes contain poisonous carbon monoxide (odorless and colorless), which can lead to serious injury or death.

How to Avoid It:

• Never inhale compressed air directly from the pump, tank, receiver, or breathing device.
• The compressor is not equipped with suitable filters for human consumption. Do not use discharge air for breathing.
• Operate and perform work only in well-ventilated areas. Follow safety instructions for sprayed materials and use certified safety equipment.
• Operate gas engines only in well-ventilated areas. Avoid inhaling exhaust fumes. Never run a small gas engine in a closed or confined area without adequate ventilation.

⚠️ WARNING: RISK OF BURSTING

Air Tank: Air tanks have a finite life and require annual inspection. Contact your state's pressure vessel inspector or call 1-800-310-3573 for assistance.

Conditions that can lead to tank weakening/explosion:

• Failure to drain condensed water regularly leads to rust and thinning of the steel tank.
• Modifications, alterations, or attempted repairs to the air tank.
• Unauthorized modifications to safety valve, pressure switch, or pilot unloader valve.

How to Avoid It:

• Drain tanks daily or every 4 hours. Replace leaking tanks immediately.
• Never drill, dent, weld, patch, or modify the air tank or its attachments. Discontinue use and replace if any such conditions exist.
• Never attempt to repair a damaged or leaking tank; replace immediately.
• Do not alter factory set pressure settings.
• Before starting, pull the safety valve ring (with tank pressure at zero) to ensure it moves freely.
• Never operate without a factory-approved safety valve.

Attachments & Accessories:

• Exceeding pressure ratings of air tools, spray guns, accessories, or tires can cause them to explode or fly apart.

How to Avoid It (Attachments):

• Read the owner's manual to determine safe maximum pressure ratings for tools and accessories.
• Never exceed manufacturer's maximum allowable pressure ratings.
• Never use the compressor to inflate small, low-pressure objects like children's toys or balls.

❗ DANGER: RISK OF INJURY OR PROPERTY DAMAGE WHEN TRANSPORTING OR STORING

What Can Happen:

• Oil leaks can cause fires, breathing hazards, serious injury, or death. Oil can damage carpets, paint, or surfaces.

How to Avoid It:

• Always keep the compressor level; never lay it on its side.
• Use a protective mat during transport to prevent damage from leaks.
• Remove the compressor from the vehicle immediately upon arrival.
• Follow local safety codes for cleanup of hazardous materials if an oil leak is found.

⚠️ WARNING: RISK OF ELECTRICAL SHOCK

What Can Happen:

• Improper grounding can result in serious injury or death from electrocution.
• Electricity can cause electric shock if the device is not used properly.
• Serious injury or death can occur if repairs are attempted by unauthorized personnel.

How to Avoid It:

• Ensure the electrical circuit provides proper grounding, correct voltage, and adequate fuse protection. Call 1-800-310-3573 with questions.
• Never operate outdoors in rain, snow, or wet conditions.
• Never let the electrical cord lay in water.
• Never operate with a damaged power cord or protective covers.
• Never touch the plug with wet hands.
• Never pull the electric cord to disconnect from the outlet.
• All electrical repairs must be performed by ROLAIR authorized personnel according to national and local electrical codes.

⚠️ WARNING: RISK FROM FLYING OBJECTS

What Can Happen:

• Serious injury and property damage can occur from debris propelled at high speeds by the compressed air stream.

How to Avoid It:

• Always wear certified safety equipment: ANSI Z87.1 eye protection with side shields.
• Never direct the air stream, nozzle, or sprayer towards yourself, others, or animals.
• Always turn off the compressor and drain tank pressure completely before maintenance or attaching hoses/tools.

⚠️ WARNING: RISK OF HOT SURFACES

What Can Happen:

• Serious burn injuries can result from touching exposed metal parts (engine, motor, pump, discharge lines) that become hot during operation and remain hot after shutdown.

How to Avoid It:

• Never touch exposed metal parts during operation or for an extended period after shutdown.
• Do not reach around shrouds or attempt maintenance until the unit has completely cooled.

⚠️ WARNING: RISK FROM MOVING PARTS

What Can Happen:

• Serious injury or death can occur if moving parts (belts, flywheels, pulleys, fans) contact you or your clothing.
• An electric compressor can restart unexpectedly when plugged in, causing injury, death, or property damage.
• Operating with damaged or missing parts, guards, or covers exposes you to moving parts and can cause injury or death.

How to Avoid It:

• Ensure all protective guards and covers are in good condition before operation. Never operate if any guard or cover is removed or damaged.
• Keep hair, jewelry, clothing, and gloves away from moving parts.
• Avoid air vents that cover moving parts.
• Always unplug the compressor when not in use.
• Always drain air tank pressure completely before attempting repairs or maintenance.
• Never allow children or adolescents to operate the compressor.
• All repairs must be made by ROLAIR factory authorized personnel.

⚠️ WARNING: RISK FROM LIFTING

What Can Happen:

• Serious injury can result from attempting to lift an object that is too heavy.

How to Avoid It:

• Always obtain assistance from others before attempting to lift any object that is too heavy for you.

⚠️ WARNING: RISK OF FALLING

What Can Happen:

• Compressor vibration can cause it to move during operation, potentially leading to a fall from a table, workbench, or other platform, causing damage and injury or death.

How to Avoid It:

• Always operate the compressor in a stable and secure position to prevent accidental movement.
• Never operate on a roof or other elevated position. Use the air hose to reach high locations.

⚠️ WARNING: RISK FROM NOISE

What Can Happen:

• Noise from this product may contribute to hearing loss under certain conditions and duration of use.

How to Avoid It:

• Always wear certified safety equipment: ANSI S12.6 (S3.19) hearing protection.

⚠️ WARNING: RISK OF UNSAFE OPERATION

What Can Happen:

• Serious injury or death can occur if the air compressor is used in an unsafe manner.

How to Avoid It:

• Review and understand all instructions in the owner's manual.
• Know how to stop the compressor at all times.
• Do not operate until thoroughly familiar with all controls.
• Do not operate if fatigued, under the influence of alcohol or drugs, or impaired in judgment.
• Stay alert and pay close attention to the task at hand.

ℹ️ CAUTION: RISK OF DAMAGE TO AIR COMPRESSOR OR PROPERTY

What Can Happen:

• Improper transport or operation may result in major repair expenses.

How to Avoid It:

• Check oil levels daily and maintain proper levels.
• Always operate in a secure and level position.
• Do not operate without an air filter or in a corrosive environment.

Gas Engine Powered Air Compressors

Note: Your gas-powered compressor may not be equipped with a spark arresting muffler. If operating near flammable materials or vegetation, an approved spark arrestor must be installed and maintained. California law (Public Resources Code sections 4442 & 4443) requires approved spark arrestors. Check local and state regulations.

Honda Engines with Optional Electric Start

Refer to the Honda owner's manual for instructions. Visit http://engines.honda.com, navigate to SUPPORT & SERVICE > Owner's Manual > GX Series engines. Find engine specifications and serial number on the engine block.

Honda Specifications & Recommendations:

Cable specifications: Positive cable: AWG #4 x 1.5 m (5.0 ft.) max. Negative cable: AWG #4 x 2.3 m (7.5 ft.) max.

ROLAIR Recommendations (for engines with electric start):

• Always drain tank pressure completely and leave drain valve open before and after starting the engine.
• Allow the compressor to run with the tank drain open for 30-40 seconds before closing to build tank pressure and cycle the engine between full throttle and idle speed.
• Locate and install battery terminal caps (boots) over battery terminals and the open (+) starter solenoid post. (Refer to part numbers like 444L8V02, 444R8V02, 444L8V14, 444R8V14, 470N9V02 for examples).
• Battery terminal caps are required by Honda to protect terminals from shorts, prevent fire, and reduce exposure to moisture and debris.

System Controls

Diagrams on pages 9 and 25 show system controls. Descriptions below correspond to numbered items.

1. SAFETY-RELIEF VALVE: Discharges tank pressure at a predetermined setting during system failure. Check daily by pulling the ring when tank is drained. An inoperable valve can lead to tank rupture or explosion. Do not tamper with it.
2. MANUAL OVERLOAD / MOTOR RESET: Protects motor from overheating. If tripped, allow motor to cool for ~5 minutes, then push reset button. Check extension cord usage if overheating occurs.
3. PRESSURE SWITCH: Controls automatic start/stop (typically 105-130 PSI). Ensure lever is "Off" before plugging in. Move to "On/Auto" to start. Never stop by unplugging; use the "Off" position.
4. REGULATOR – WORKING PRESSURE: Adjust output pressure by lifting and rotating the knob. Clockwise increases, counterclockwise decreases. Push down to lock. Never exceed tool pressure rating.
5. PRESSURE GAUGE(S): Measure tank/storage pressure and output/working pressure.
6. DRAIN VALVE(S): Allows daily draining of moisture from storage tank(s). Open carefully and slowly.
7. AIR INTAKE FILTER: Prevents foreign matter from entering the engine or pump. Clean or replace regularly. Use warm soapy water or low compressed air for cleaning. Check canisters for cracks.
8. PILOT-UNLOADER VALVE: Used on gas units and for continuous operation on electric units. Discharges compressed air to atmosphere when tank reaches top pressure setting, redirecting it to the tank when pressure drops. Do not replace without draining tank pressure. Factory settings should not be exceeded.
9. SIGHT GAUGE/DIPSTICK: Check oil level daily. Dipstick also acts as crankcase vent. Maintain oil level at 2/3 full on sight gauge or at the maximum mark on dipstick.
10. CHECK VALVE: Seals and maintains tank pressure after top end pressure setting is reached. Works with pressure switch relief valve for loadless start. A burst of air from the pressure switch relief valve indicates it's working.
11. BREATHER/OIL FILL PLUG: Vents crankcase pressure. Direct-drive units vent through dipstick; belt-drive units vent through oil-fill plug. Never operate without dipstick or oil-fill plug.
12. AUTOMATIC-IDLE CONTROL: (Gas units) Decreases engine speed when top pressure is reached. Top RPM is factory set. Idle speed is controlled by a screw on the carburetor. Adjust for colder temperatures if needed.
13. COLD-START VALVE: (Direct-drive) Allows motor/pump to warm up before tank pressure is applied. (Belt-drive) Manual drain valve on pump aftercooler assists cold weather starting. Open drain, run unloaded for a minute, then close.
14. SCHMIDT BELT-TIGHTENING DEVICE: (Gas units only) Unique system for maintaining proper belt tension. Loosen locknuts, rotate adjustment bolt clockwise to achieve tension, then retighten locknuts.
15. VIBRATION DAMPENER(S): Rubber pads beneath tank assembly protect against vibration damage.
16. ENGINE KILL SWITCH: Easily stops the engine. Do not move throttle lever when stopping. Move kill switch to "On" before pulling recoil rope to start.
17. ENGINE CHOKE: Move to left (closed) for cold start. Move to right (open) after start-up. Operating with choke partially closed can foul spark plug and cause carbon buildup.
18. FUEL SHUT-OFF VALVE: Move to "Open" (right) only when engine is operating. Close (left) when not in use. Do not move or transport with valve open.

Pre-Start Checklist

Read manual thoroughly and understand all warnings, controls, and instructions before operating.

1. ALWAYS OPERATE IN A LEVEL POSITION: Splash-lubricated pumps require the dipper to remain submerged in oil. Operation over 10 degrees can seize the pump and void warranty.
2. OPERATE IN A CLEAN, DRY AND WELL VENTILATED AREA: Allow 18" clearance for cooling. Do not operate in rain, standing water, or areas with explosive gases/fumes. Do not operate in an enclosed area.
3. CHECK OIL LEVEL DAILY AND CHANGE AT REGULAR INTERVALS: Refer to maintenance section for type/weight and change intervals.
4. INSPECT/CLEAN/CHANGE INTAKE ELEMENTS: Dirt ingestion causes premature wear. Check intake filters daily.
5. USE LONGER, PROPERLY SIZED AIR HOSE RATHER THAN EXTENSION CORDS: Refer to the Electric Extension Cord Table for proper gauge and length. Inadequately sized hoses can cause pressure drops.
6. DO NOT USE A GENERATOR AS THE POWER SOURCE: Inductive motors require high starting current that most generators cannot provide.
7. CHECK TENSION OF BOLTS, BELTS, AND HARDWARE: Loose components cause vibration and premature failure.
8. MAINTAIN RUBBER VIBRATION PADS: Essential for preventing premature compressor failure. Operation without them voids warranty.
9. DRAIN MOISTURE FROM AIR TANKS DAILY: Water causes internal corrosion. Keep drain valves closed if storing for extended periods.
10. DO NOT ALTER FACTORY RPM SETTINGS ON GAS-POWERED COMPRESSORS: Factory settings ensure maximum performance, fuel efficiency, and service life. Altering them voids warranty.

Electric Extension Cord Table:

Operation

⚠️ WARNING: Your safety and the wellbeing of others during operation are paramount. Read and understand this manual before operating.

Wet Conditions:

Do not operate or store in damp or wet conditions, or after exposure to rain, sleet, ice, snow, or moisture. This can lead to electric shock, rust, ice formation, and dangerous operation. Always operate and store in a clean, dry, well-ventilated location.

Direct-Drive Electric Operation:

Follow Pre-Start Checklist. Slowly open tank drain to remove condensate, then keep open briefly after starting to warm up. Ensure pressure switch lever is "Off" before plugging in. Move to "On/Auto" to build pressure. Rotate regulator knob counterclockwise to 0 PSI before attaching hose. Set working pressure by rotating clockwise and locking. Always use the "On/Auto/Off" lever to start/stop; never unplug. Store in a warm/dry location.

Belt-Drive Electric Operation:

Start/Stop Operation:

Follow procedures for direct-drive electric. Open pump aftercooler drain valve for cold starts. Electric motors should not exceed 15 starts per hour. Consult dealer for conversion kits if experiencing overload due to frequent starts.

Constant-Speed Operation:

Use for heavy use to extend motor life and prevent overheating. If built for continuous operation, take special care to start/stop safely. Always shut off power at the main breaker or switch before plugging/unplugging. Drain tanks and open aftercooler drain valve before starting, especially in cold temperatures. Never stop by pulling the plug; use the breaker or switch.

Dual-Control Operation:

Allows easy transition between start/stop and continuous running. See Figure 1 for instructions. Always flip pressure switch lever to "Off" before plugging/unplugging.

Duty Cycle:

Belt-driven units have S1 or 100% duty cycle motors/pumps and can operate continuously with proper ventilation and power. Excessive starts may trip motor overload. Contact Customer Service if overload problems occur repeatedly. Some direct-drive models (FC1500HBP2, FC1500HS3, JC10) have a 70% duty cycle; continuous operation will cause internal overload to shut down the motor until it cools.

Operation (Continued)

Gas Powered

Refer to "System Controls" section (items 12, 16, 17, 18) for automatic idle control, kill switch, choke, and fuel shut-off valve. Engine throttle arm is locked at maximum RPM for service life; no adjustment needed to start/stop. Use pump aftercooler or intercooler drain valve for cold starts. Keep fuel tank free of dirt and debris. Ensure regulator is closed (0 PSI) before attaching hose. A slight hissing noise during idle is normal. Store in a warm/dry location and perform maintenance as indicated.

Freezing Temperatures:

Proper fluid maintenance and warm-up are mandatory. Water can freeze, blocking air flow. Drain tanks/lines after each use and leave drain valves open when not in use. If frozen, thaw completely before starting. Gradually increase temperature above freezing and drain moisture.

Cold Weather Best Practices:

• Do not attempt to start a frozen compressor; thaw completely first.
• Store in a clean, dry area consistently above freezing.
• Change pump and engine oil to winter grade (check owner's manual).
• Before starting, open tank drains and run for 45-60 seconds with drains open before closing to build pressure.
• Use lubricator with de-icing fluid for air lines if needed.
• Contact ROLAIR dealer or customer service for additional questions.

High-Altitude Operation:

Atmospheric pressure decrease reduces CFM output (approx. 3% per 1000 ft). Air is less dense and cools less effectively, potentially causing electric motor overheating. Direct-drive or hand-carry units with cold-start valves may need modification. Gas engine carburetors may need re-jetting. Contact Customer Service if performance issues arise at higher elevations.

Maintenance

Your compressor requires periodic maintenance for optimal performance. Always unplug or shut down the compressor, drain tanks completely, and allow it to cool before servicing.

IMPORTANT: Replace oil after the first 50 hours of operation.

Maintenance Hints:

1. Use soap/water solution to check for air leaks.
2. Never clean filters with flammable solvent.
3. Retorque head bolts only after the 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. Apply heat to loosen Loctite seal on drain valves, engine pulleys, and flywheels before removal.

Lubrication

Check pump oil level before each use. Maintain oil level at the maximum mark on the dipstick or 2/3 full in the sight gauge. Do not operate with inadequate or excessive oil; warranty does not cover failures due to incorrect oil levels.

DO NOT USE A DETERGENT OIL!

NOTE: Unit must be level when in operation.

Oil Chart:

Recommended SAE Viscosity Grades are shown graphically based on operating temperature range.

Maintenance Schedule:

Maintenance (Continued)

Torque Chart (Inch/Lb)

Determine pump type using the suffix of the Model number (e.g., 4090HK17 uses K17 pump).

Pilot Valve Adjustment

NOTE: Should only be performed by ROLAIR factory authorized personnel.

Resetting Differential (2):

Ensure top toggle lever is positioned correctly. Loosen locknut (1) by turning counterclockwise. Gently turn differential setting (2) clockwise until internal rod contacts steel ball. Turn differential (2) counterclockwise 1/4 turn. Tighten locknut (1) to secure, then proceed to top end setting.

Top-End Setting (4):

Loosen locknut (3) counterclockwise. Turn setting (4) clockwise to increase top end pressure, counterclockwise to decrease. Start by turning counterclockwise one full turn, then proceed to fine-tuning.

Fine-Tuning Instructions:

Start engine/motor and observe tank pressure. As pressure nears 100-130 PSI, the pilot valve should unload, causing the engine to idle. If it doesn't unload by 130 PSI, slowly turn top end setting (4) counterclockwise until it unloads prematurely (at 100 PSI). Then, turn (4) clockwise in 1/4 turn increments, tap internal rod at toggle attachment, and repeat until desired setting is reached. If pilot valve "rifles" (sputters), fine-tune differential setting (2) 1/16 turn in either direction until rifling stops. Secure settings by tightening locknuts (1 & 3).

Schmidt Belt-Tightening Device (For Gas Units Only)

NOTE: Should only be performed by ROLAIR factory authorized personnel.

1. Loosen engine hold-down locknuts until washers spin freely.
2. Rotate 1/2" adjusting bolt clockwise until desired tension is reached (See Figure 4).
3. Retighten locknuts to secure the engine.

Drive Pulleys

Pulleys must be aligned, and belt tension set to specification. Improper alignment or tension can cause motor overloading, excessive vibration, and premature belt/bearing failure (See Figure 5).

Gasoline Engine RPM Settings:

NOTE: Engine RPMs are factory set for maximum efficiency. Adjusting RPMs above factory specification voids the warranty.

Troubleshooting

⚠️ WARNING: Ensure you understand all safety warnings and system controls before attempting maintenance or repair. Always drain tank pressure completely, unplug the power cord, and allow the unit to cool before performing any maintenance or service.

Guarantee

Associate Engineering Corporation warrants ROLAIR compressors to be free of defects in material and workmanship for 12 months from the date of original retail purchase, or 18 months from the date of manufacture, whichever occurs first.

If a defect is reported within the warranty period, the company will, upon shipment of the compressor to their plant (transportation prepaid), correct the nonconformity by repair or furnish a replacement part F.O.B. their plant.

Associate Engineering Corporation is not liable for unauthorized repairs, replacements, adjustments, or labor costs performed by the purchaser.

This warranty is in lieu of all other warranties, expressed, implied, or statutory (including warranties of merchantability and fitness for purpose), and all other obligations and liabilities of Associate Engineering Corporation. Associate Engineering Corporation neither assumes nor authorizes any other person to assume any other obligation or liability.

Associate Engineering Corporation is not liable for consequential, incidental, or special damages, nor for improper selection of the compressor for a particular application.

Quality

Associate Engineering Corporation is committed to continuous quality control and research. Their goal is to provide users with all available experience and engineering in every product.

ROLAIR offers a full line of air compressors meeting modern air requirements, featuring the latest advancements.

Address: 606 South Lake Street > P.O. Box 346 > Hustisford, WI 53034-0346

Contact: 920.349.3281 | Fax: 920.349.8861 | www.rolair.com

Schematic for 4090HMK103

The schematic diagram shows the overall assembly of the ROLAIR 4090HMK103 air compressor. Key components include:

• Air filter assembly (1)
• Pump with flywheel (8)
• Engine (47)
• Tank assembly (35)
• Wheels (41)
• Various regulators, gauges, valves, and fittings (numbered 9-25, 28-34)

Diagram showing the layout of components for the ROLAIR 4090HMK103 model.

Parts List for Model 4090HMK103

As an added safety measure, belt driven models built after July 1, 2015 include additional safety valve on check valve. *Safety valve not shown but may be ordered separately.

Schematic for Model PMP12MK103

The schematic diagram illustrates the components of the ROLAIR PMP12MK103 pump. Key parts include:

• Intake Filter Assembly (1)
• Head (3)
• Cylinder (7)
• Complete Piston Assembly (8)
• Crankshaft (11)
• Flywheel (19)
• Various gaskets and seals (e.g., 23)

Diagram showing the assembly of the ROLAIR PMP12MK103 pump.

Parts List for PMP12MK103

*Includes "O" ring for head and upper cylinder gasket

**Rings for both pistons and gasket set (#23)

***Two connecting rod/piston assemblies, ring set and gasket set (#8, 9, 10 & 23)