Replace a worn horizontal-shaft pressure washer pump on a Simpson MorFlex 40224, 40225, 40226, or Santoprene 41182 with a 4000 PSI 4.0 GPM plunger pump that ships with five nozzles and a built-in pressure regulator for immediate return to full cleaning performance. The plunger design delivers 4000 PSI max (3100 PSI recommended working pressure for typical residential and light industrial cleaning and longer pump life) with 4.0 GPM max flow, finishing driveway, deck, siding, fence, and patio jobs faster than 3000 PSI class pumps. A 1 in. (25.4 mm) horizontal shaft fits 13-15 HP engine setups, and a standard SAE bolt pattern pairs with the MorFlex 40224/40225/40226 and Santoprene 41182 — match engine orientation, PSI, GPM, shaft diameter, and pump inlet/outlet connections before install. An oil sight glass lets a user check oil without disassembly; change oil every 60 hours, and the anodized build (3/4 in. NH inlet, 3/8 in. quick-connect outlet) extends service life to 500 hours of use. A built-in pressure regulator adjusts output based on engine speed and reduces pressure during idle pauses, lowering noise and extending equipment life. Cold-water use only. Primary material copper and aluminum. 21.38 lbs. (9.7 kg), model QXB-9. Fit for household driveway, deck, fence, siding, and light industrial cleaning.