RKV4037-PKG | 4.0 GPM 3700 PSI Triplex Pump Kit Unloader Installed

RKV4037-PKG by Annovi Reverberi — Complete Triplex Pump Package | 4.0 GPM | 3,700 PSI | Bronze Connecting Rods | Forged Brass Manifold | Gymatic C2 Unloader | F24 SAE J609a 1″ Shaft | Direct Drive Gas Engine | Everything in One Box

The RKV4037-PKG by Annovi Reverberi is a complete, installation-ready triplex ceramic plunger pump package engineered for direct drive gas engine-powered pressure washing systems requiring 4.0 GPM at 3,700 PSI. Rated at 4.0 GPM and 3,700 PSI, the RKV4037-PKG delivers 14,800 cleaning units — the combined output of a professional-grade contractor, fleet, agricultural, industrial, and municipal cleaning platform — through bronze connecting rods, solid ceramic plungers, a forged brass manifold, stainless steel valves, dual redundant packing, and an F24 SAE J609a direct-drive flange with 1″ shaft for direct coupling to compatible gasoline and diesel engines. Every fitting, every bolt, the unloader, and the manual ship in one organized box. Open it. Mount it. Hook up and wash. As part of Annovi Reverberi’s pump and unloader assemblies stocked and supported by WSHPWR, the RKV4037-PKG is the complete solution for operators who have no interest in sourcing components one at a time.

This is not a pump that happens to have an unloader attached. The RKV4037-PKG is a factory-engineered, factory-assembled, factory-tested complete system in a box — designed by Annovi Reverberi in Modena, Italy, distributed across North America by AR North America, and backed by a 5-year US limited warranty. Whether you are replacing a failed pump on an existing contractor rig, building a new skid, outfitting a flatbed for multi-unit mobile wash operations, or specifying a pump for an OEM installation — the RKV4037-PKG eliminates the guesswork, the return trips, and the compatibility risk. Everything you need to put 14,800 cleaning units to work is already in the box.

Everything in One Box — The RKV4037-PKG Complete Package Contents

No Return Trips to the Parts Counter. Zero Sourcing Guesswork. Bolt On and Go.

Open the RKV4037-PKG box and find everything required for a complete, same-day installation:

• RKV4037 triplex ceramic plunger pump — factory-tested, pre-lubricated with break-in oil, and ready to mount. Bronze connecting rods, solid ceramic plungers, forged brass manifold, stainless steel valves, dual redundant packing, oversized crankshaft bearings — all factory-installed and factory-verified before shipment.
• Gymatic C2 adjustable unloader with banjo bolts and sealing O-rings — factory-matched and factory-installed for the 4.0 GPM / 3,700 PSI duty point. Smooth pressure regulation and safe bypass protection from the first startup. No unloader sourcing, no compatibility guesswork.
• Fittings and mounting hardware — every fitting and fastener required for integration onto contractor skids, fleet wash frames, OEM installations, and flatbed mobile wash rigs. Organized in the box. Ready to install.
• Chemical injector and suction hose — not included — the RKV4037-PKG delivers straight high-pressure water output. When detergent capability is required, a downstream chemical injector and suction assembly are sourced separately and connected to the system outlet line. This keeps the package clean and allows operators to specify the injector type, draw rate, and connection style that matches their cleaning program.
• Factory break-in oil — crankcase pre-filled and ready. First startup protection is already handled.
• Oil sight glass and vented dipstick — at-a-glance oil monitoring from day one.
• Installation and maintenance manual with exploded parts diagram — complete setup, operating, service, and rebuild procedures with Annovi Reverberi part numbers for every component. AR North America parts availability confirmed across North America.

Decoding the RKV4037-PKG

What This Annovi Reverberi Pump Package Designation Tells You

• RKV — Pump series: RKV Series heavy-duty triplex plunger pump — Annovi Reverberi’s professional commercial and industrial gas engine pump platform
• 40 — Flow rate: 4.0 GPM
• 37 — Maximum pressure: 3,700 PSI — 4.0 × 3,700 = 14,800 cleaning units
• PKG — Complete package: pump, Gymatic C2 unloader with banjo bolts, fittings, mounting hardware, manual, and factory break-in oil — everything required for a complete engine-to-pump installation in one organized box

Key Specifications

RKV4037-PKG Technical Details at a Glance

• Flow Rate: 4.0 GPM (gallons per minute)
• Maximum Pressure: 3,700 PSI
• Cleaning Units: 14,800 (GPM × PSI)
• Operating Speed: 3,400 RPM — direct drive gas engine
• Pump Type: RKV Series triplex ceramic plunger pump
• Flange: F24 — SAE J609a, 1″ hollow keyway shaft, direct drive gas and diesel engine compatible (Annovi Reverberi part AR41866)
• Connecting Rods: Bronze — heavy-duty specification for 3,700 PSI continuous-duty operation
• Manifold: Forged brass — maximum corrosion resistance and structural integrity under sustained high-pressure operation
• Plungers: Solid ceramic — wear resistance and thermal stability
• Valves: Stainless steel inlet and discharge — reliable sealing and consistent performance under high pressure and chemical exposure
• Packing: Dual redundant — twice the sealing protection, extended service intervals, improved uptime in continuous-duty environments
• Volumetric Efficiency: Approximately 93% — nearly all input energy transferred into usable water flow; cooler running under load
• Bearings: Oversized crankshaft bearings — reduced wear and vibration at operating speed
• Lubrication: Vented oil-bath crankcase — continuous lubrication and heat dissipation during long duty cycles
• Unloader: Gymatic C2 — factory-matched, factory-installed, banjo bolts and O-rings included
• Chemical Injector / Suction Hose: Not included — chemical delivery managed externally; downstream injector sourced separately when detergent application is required
• Warranty: 5-year limited warranty — US-based coverage through Annovi Reverberi North America

Engine Compatibility — What Drives the RKV4037-PKG

F24 SAE J609a. 1″ Hollow Keyway Shaft. Direct Drive. Broad Engine Compatibility.

The RKV4037-PKG‘s F24 SAE J609a direct-drive flange accepts a 1″ hollow keyway shaft — the standard configuration for commercial gas and diesel engines in the 13–22 HP range. Confirmed compatible engine platforms include:

• Harbor Freight Predator 420cc / 13 HP — the Predator 420cc is a direct, value-priced replacement for Honda GX390, Briggs & Stratton XR2100, and Kohler CH440 engines. Widely used in micro-OEM and DIY pressure wash system builds, contractor flatbed rigs, and multi-unit mobile wash operations where cost per cleaning unit matters. The RKV4037-PKG pairs directly with the Predator 420cc at the 1″ SAE keyway shaft interface — no adapter, no modification.
• Harbor Freight Predator 459cc / 15.8 HP Max Performance — up to 10% more torque than the standard 420cc. Direct replacement for Honda GX390, Briggs & Stratton XR2100, and Kohler CH440. Compatible with the RKV4037-PKG F24 1″ keyway shaft — the preferred single-cylinder Predator pairing for sustained high-pressure continuous-duty operation.
• Harbor Freight Predator 670cc / 22 HP V-Twin — for operators running multi-pump flatbed rigs or high-demand commercial systems where engine overhead is required. The Predator 670cc replaces Honda GX630/660/690 and Briggs & Stratton Vanguard configurations at a fraction of the OEM engine cost.
• Honda GX390 — 389cc, 1″ SAE J609a keyway shaft. The benchmark commercial pressure washer engine. The RKV4037-PKG is direct-mount compatible.
• Briggs & Stratton XR2100 / Vanguard series — 420cc and above, 1″ SAE keyway. Direct-mount compatible with the RKV4037-PKG F24 flange.
• Kohler CH440 / Command series — 429cc, 1″ SAE keyway. Direct-mount compatible.
• General diesel engines — any gas or diesel engine with a 1″ SAE J609a horizontal keyway shaft at 3,400 RPM operating speed is compatible with the RKV4037-PKG F24 direct-drive flange.

Built for the Predator-Powered Contractor Rig

Flatbed. Multi-Unit. Mobile Wash. Maximum Output Per Dollar Spent.

The mobile pressure washing contractor community has built an entire micro-OEM market around pairing Annovi Reverberi pump packages with Harbor Freight Predator engines. The math is straightforward:

• Build your own system — keep the savings — a Predator 420cc engine paired with the RKV4037-PKG delivers 14,800 cleaning units of professional commercial cleaning output at a fraction of the cost of a comparable OEM-assembled pressure washer. The contractor who builds their own system controls the component quality, the layout, and the cost.
• Standardize your fleet for maximum uptime — contractors outfitting flatbed pickup trucks and trailers with multiple identical Predator/RKV4037-PKG stations gain the operational advantage of standardized parts, standardized service procedures, and standardized performance. When one unit needs a rebuild, every other unit on the rig uses the same parts.
• AR North America parts availability — every wear component in the RKV4037-PKG is stocked through AR North America’s domestic distribution network. Rebuild kits, packing kits, valve assemblies, C2 unloader service parts — all available nationally. Your rig stays running.
• Quality control you own — building your own system with a WSHPWR pump package means you know exactly what went into it, exactly what it is rated for, and exactly what it will take to service it. No assembly line compromises. No unknowns.

93% Volumetric Efficiency and Dual Redundant Packing — Why This Pump Runs Longer

More Output Per HP. Less Heat. More Uptime. Longer Service Intervals.

• 93% volumetric efficiency — the RKV4037-PKG’s precision-machined internal hydraulic design and valve timing transfer approximately 93% of input energy from the engine into usable water flow at the outlet. Higher efficiency means the pump runs cooler under load — less heat means less wear on ceramic plungers, packing seals, and valve seats at 3,700 PSI operating pressure.
• Dual redundant packing system — two independent sealing stages on each plunger in the RKV4037-PKG provide twice the sealing protection of single-stage designs. Extended service intervals, reduced leakage risk, and improved uptime in the demanding stop-start cycles of contractor cleaning operations.
• Thermal relief protection — built-in thermal relief safeguards protect the RKV4037-PKG pump head from overheating during extended bypass periods, increasing seal life and preventing heat-related damage during the idle intervals common in mobile wash operations.
• Oversized crankshaft bearings — the RKV4037-PKG’s oversized bearing assembly stabilizes the drivetrain at 3,400 RPM operating speed, reducing wear and vibration across long daily duty cycles on contractor rigs and fleet wash systems.

Typical Applications

Where the RKV4037-PKG Delivers Best Results

• Mobile contractor wash rigs and flatbed builds — the RKV4037-PKG is the complete package for contractors building or rebuilding gas engine-powered mobile pressure washing systems. Mount to a Predator 420cc or compatible engine, install the included fittings, and the rig is operational. Add a downstream injector and suction assembly when chemical application is required — no other sourcing needed.
• Fleet wash bays — buses, trucks, trailers, and commercial delivery vehicles where 4.0 GPM output and 3,700 PSI cleaning force deliver effective fleet cleaning performance at professional duty cycles
• Agricultural operations — barn sanitation, tractor and implement washdown, and irrigation line flushing where the RKV4037-PKG’s high-output complete package supports demanding agricultural cleaning programs
• Industrial plants and manufacturing facilities — conveyor wash, machine maintenance, degreasing stations, and general plant sanitation where 14,800 cleaning units and bronze rod continuous-duty construction meet sustained industrial cleaning demands
• Food and beverage facilities — USDA-compliant wash stations when used with appropriate sanitation procedures and compatible detergents delivered through a separately sourced downstream chemical injector system
• Municipal services — sidewalk and street cleaning, service bays, and public works fleet maintenance where standardized, serviceable pump packages support scheduled municipal cleaning programs

5-Year US Warranty, National Parts Availability, and Wholesale Pricing

Built in Italy. Distributed Across North America. Backed for Five Years.

The RKV4037-PKG is protected by Annovi Reverberi’s 5-year limited warranty through the US-based warranty and service network administered by AR North America. Every internal wear component — ceramic plungers, bronze connecting rods, forged brass manifold seals and o-rings, stainless valve seats, Gymatic C2 unloader service parts, dual redundant packing kits, and oversized crankcase bearings — is stocked nationally through authorized AR North America distribution channels. Contractors, fleet operators, agricultural operations, industrial facility managers, OEM equipment builders, resellers, and volume buyers are invited to contact the WSHPWR wholesale team for pricing on the RKV4037-PKG and the complete WSHPWR pump package lineup. WSHPWR maintains one of the most complete Annovi Reverberi inventories available through any US web store — with thousands of products in stock and a continually expanding catalog.

14,800 Cleaning Units. 3,700 PSI. 4.0 GPM. F24 SAE J609a. Gymatic C2. Bronze Rods. Everything in One Box.

Italian Engineering. Predator-Compatible. Complete Factory Package. 5-Year US Warranty.

Stop sourcing parts one at a time. Stop guessing which unloader fits. Stop making return trips. The RKV4037-PKG is the complete Annovi Reverberi pump package for contractors, fleet operators, agricultural teams, industrial facilities, OEM builders, and Predator-powered flatbed rig operators who need 4.0 GPM at 3,700 PSI with zero installation surprises. Bronze connecting rods. Forged brass manifold. Dual redundant packing. 93% volumetric efficiency. Gymatic C2 unloader. Every fitting and every bolt. Factory-tested. Pre-lubricated. Five-year US warranty. One box. Same-day install.

Volume buyers and contractors building multi-unit systems can reach the WSHPWR wholesale team directly at wholesale@wshpwr.com to discuss pricing across the complete Annovi Reverberi pump package lineup.