OEM axial-cam pumps
Current replacement kits include horizontal and vertical classes such as 90026, 90028 and 90029 with published PSI/GPM and shaft information.
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SIMPSON Pressure Washer Guide
SIMPSON pressure washers use multiple engine, pump and drive combinations across residential, professional and industrial lines. Match the exact model and pump system before choosing replacement parts, hoses, guns, nozzles or attachments.
SIMPSON is a machine + pump + accessory ecosystem
Current SIMPSON lines range from residential axial-cam machines to professional and industrial triplex systems. For compatibility, identify the washer model, pump model/brand, output and connection path rather than relying only on the SIMPSON name.
For replacement components, continue to SIMPSON pressure washer parts & compatibility.
Current SIMPSON families cover very different duty classes
| Family / example | Published output | Pump architecture | What it means for matching |
|---|---|---|---|
| MegaShot MS61228 | 3000 PSI / 2.4 GPM | OEM Technologies axial cam | Residential/premium-residential class; pump and hose/accessory requirements differ from 4-GPM pro machines. |
| MegaShot MS61084 | 3400 PSI / 2.5 GPM | OEM Technologies axial cam | Higher-output residential gas class with model-specific engine/pump combination. |
| PowerShot PS60869 | 4000 PSI / 3.5 GPM | AAA triplex | Professional class; downstream hoses, guns and attachments must support the higher output. |
| Pro Series 4000 | 4000 PSI / 3.5 GPM | AAA industrial triplex | Current professional package with 50-ft Monster hose and side-assist gun. |
| Aluminum ALH4240 | 4200 PSI / 4.0 GPM | CAT industrial triplex | Contractor/high-output class; 4-GPM nozzle and surface-cleaner sizing becomes important. |
| Industrial IS4240131 | 4200 PSI / 4.0 GPM | COMET triplex / belt drive | Shows that the SIMPSON brand spans different pump brands and drive systems. |
MegaShot: residential output does not mean one replacement pump
Current MegaShot pages show multiple engine and output combinations. MS61228 uses a Honda GCV170 with an OEM Technologies axial-cam pump at 3000 PSI / 2.4 GPM, while MS61084 uses a Kohler SH270 at 3400 PSI / 2.5 GPM. Older/discontinued models also remain searchable.
That is why a search for “SIMPSON pressure washer pump” should start with the exact model and existing pump—not a generic “MegaShot pump.”
PowerShot, Pro Series, Aluminum and Industrial
Professional SIMPSON machines increasingly make flow, pump serviceability and downstream component rating central to the system. The current PowerShot PS60869 uses a Honda GX270 and AAA triplex pump at 4000 PSI / 3.5 GPM. The current Pro Series comparison spans 3500/2.5, 3700/2.5 and 4000/3.5 classes. Industrial listings extend into belt- and gear-drive designs and substantially higher flow.
Use the commercial pressure-washer guide and PSI vs GPM assistant to define the machine class before comparing merchant listings.
SIMPSON pump identity is especially important
AAA triplex pumps
Current kits include 90036, 90034 and 90039 among others. Shaft diameter and engine orientation are explicit compatibility variables.
Other pump brands
Current SIMPSON pressure-washer filters also include CAT, COMET, UDOR and General Pump. A SIMPSON frame does not imply an AAA pump.
Model parts lists
Many current machine pages expose manuals and replacement-parts lists. Those should outrank retailer compatibility claims.
After you identify the required SIMPSON class
The ALH4240 is one documented 4200 PSI / 4.0 GPM CAT-triplex professional example. Treat it as a specific machine class, not a default recommendation for every user.
Manufacturer sources
- SIMPSON — current pressure-washer lineup
- SIMPSON — current MegaShot lineup
- SIMPSON — MegaShot MS61228
- SIMPSON — PowerShot PS60869
- SIMPSON — current Pro Series comparison
- SIMPSON — current Industrial Pressure Washers
- SIMPSON — replacement pump lineup
Sources reviewed August 28, 2026. PressureWasherMatch.com is independent and is not affiliated with or endorsed by SIMPSON.
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Frequently asked questions
What is the difference between SIMPSON MegaShot and PowerShot pressure washers?
Current MegaShot models are positioned as premium residential gas pressure washers and commonly use OEM Technologies axial-cam pumps. PowerShot models are professional gas pressure washers and current examples use serviceable AAA triplex pumps. Exact engine, pump and output still vary by model.
Does every SIMPSON pressure washer use an AAA triplex pump?
No. Current SIMPSON machines use several pump brands and designs, including OEM axial-cam pumps and AAA, CAT, COMET, UDOR and General Pump triplex pumps depending on model and series.
Are SIMPSON pressure washer accessories universal?
Some SIMPSON accessories are explicitly marketed with common M22 or quick-connect interfaces and published pressure/flow ranges, but that still requires matching the exact machine and accessory rating. Other parts are model-specific.
Can I replace a SIMPSON pump by matching PSI and GPM?
No. SIMPSON replacement-pump pages also publish shaft diameter, horizontal or vertical engine orientation and fitment caveats. Mounting, shaft, RPM/power, ports, unloader and clearance still need verification.
Which SIMPSON line is intended for professional work?
Current PowerShot, Pro Series, Aluminum and Industrial/SuperPro lines include professional or commercial configurations. Use the manufacturer’s exact model classification and specifications rather than assuming a series name alone defines duty.
Where can I find SIMPSON parts lists?
Many current SIMPSON model pages provide an Order Parts path and downloadable replacement-parts lists or manuals. Start with the exact pressure-washer model before selecting a pump or accessory.