HYD-RK2120NB-DD Hydraulic Pump | 5.5 GPM 2900 PSI

HYD-RK2120NB-DD | Hydraulic Motor Pump | 5.5 GPM 2900 PSI | Forged Brass Head

HYD-RK2120NB-DD refuses the compact class’s usual trade: an Annovi Reverberi RK 21.20-class drive package delivering 5.5 GPM (21 L/min) at up to 2900 PSI (200 bar) at 1450 RPM, with a forged brass head on solid-shaft construction — the N and B in the suffix, per AR North America’s own designation system. Most buyers at this size are handed a choice: the 5.5 GPM tier at 2200 PSI, or full commercial pressure capped at 4 GPM. The HYD-RK2120NB-DD answers “both,” from AR’s proven F38 close-couple architecture on hydraulics most machines already carry.

The combination reads directly as work rate. Against the 4 GPM workhorse tier at the same pressure, this pump puts nearly 40% more water on target — mud, grease, and seasonal buildup leave in fewer passes, and a fleet washdown day shortens to match. Against the 5.5 GPM / 2200 PSI tier, it adds the pressure margin that turns rinsing capability into cleaning authority on construction equipment, agricultural machinery, and municipal fleets where grime is measured in seasons.

HYD-RK2120NB-DD Specifications

• SKU: HYD-RK2120NB-DD
• Configuration: Hydraulic drive pump — RK-class with F38 close-couple interface for direct motor mounting
• Pump: Annovi Reverberi RK 21.20-class high-pressure triplex plunger pump (228-series frame)
• Head Material: Forged brass (B designation) with stainless wet-end components
• Shaft: Solid shaft (N designation)
• Flow Rate: 5.5 GPM (21 L/min)
• Maximum Discharge Pressure: 2900 PSI (200 bar)
• Rated Speed: 1450 RPM — never overspeed
• Pump Power Requirement: Approximately 10.5 HP at full duty
• Inlet Ports (2): 1/2″ F
• Discharge Ports (2): 3/8″ F
• Maximum Fluid Temperature: 140°F
• Plungers: One-piece ceramic
• Drive Interface: F38 close-couple flange (SAE A 82.55)

Hydraulic Supply Requirements

Full 5.5 GPM at 2900 PSI performance calls for roughly 13 hydraulic horsepower — on the order of 8.2 GPM (31 L/min) of oil at approximately 2,850 PSI working pressure, consistent with AR’s published gear-motor pairing for the adjacent RK 21.21 model (198 bar at 31 L/min on the 19cc motor). Standard skid steer auxiliaries and truck systems carry the flow easily; the number to verify is working pressure, since circuits that relieve near 3,000 PSI leave little margin above the motor’s demand. Protect the motor with a properly set relief, route return oil short and filtered to tank, and provide oil cooling for continuous trigger-on duty. Call WSHPWR with your machine’s auxiliary flow, pressure, and relief setting and we will confirm the match before you order.

Forged Brass, Honestly Specified

Forged brass is the industry’s proven head material for clean-water commercial service — dimensionally stable at pressure, corrosion-resistant in ordinary municipal and well supply, and fully serviceable with AR’s standard repair kits. For the majority of fleet, construction, and agricultural washdown, it is simply the correct specification, delivering full platform performance without paying for armor the duty never stresses. Operations that run daily detergent programs, sanitation chemistry, salt exposure, or reclaimed water should ask about nickel-plated and stainless head options across this platform — WSHPWR will spec the armored build where the chemistry genuinely demands it, and the HYD-RK2120NB-DD everywhere it doesn’t.

Direct-Drive Simplicity

The hydraulic motor mounts through AR’s F38 close-couple flange onto the solid shaft — one centerline, no belts, pulleys, guards, or field alignment, minimal side loading on bearings and seals, and output independent of the host machine’s engine speed. Motor and pump dismount independently at the flange when service calls, and the package installs as a bolt-down unit in cabinets, tool compartments, and skids.

RK-Series Construction

The 228-series frame carries the forged brass head over stainless wet-end components, one-piece ceramic plungers for heat dissipation and abrasion resistance, and a die-cast aluminum crankcase with oil sight glass. Intake and delivery valves sit behind service plugs in the head for inspection without dismounting the HYD-RK2120NB-DD — the same architecture and repair kits as every RK pump in the field, which keeps parts cost and downtime at the bottom of the class.

Installation & Operation Notes

Mount horizontally and confirm motor rotation at commissioning. Feed the inlet from a flooded, filtered supply with short, unrestricted plumbing. Fit an unloader set against working pressure, verify the hydraulic-side relief against the motor’s rating, and size nozzle orifices to the 5.5 GPM duty point — orifices carried from 4 GPM systems will spike pressure and park the unloader in bypass. Hold 1450 RPM as the ceiling and winterize before cold-weather storage.

Quality Assurance & Maintenance

Every HYD-RK2120NB-DD ships factory-tested for flow rate, pressure stability, and vibration. Maintenance follows AR’s standard RK schedule — crankcase oil changes, seal inspection, periodic valve checks with AR repair kits — with the moderate frame loading at this duty point keeping intervals comfortably routine.

HYD-RK2120NB-DD Key Features & Applications

• 5.5 GPM at 2900 PSI, 1450 RPM — flow and pressure together in the compact RK class.
• Forged brass head and solid-shaft build (NB designation) — the correct spec for clean-water duty.
• Nearly 40% more water than the 4 GPM tier at commercial stripping pressure.
• Runs on ~8.2 GPM of oil (~13 hydraulic HP) — standard auxiliary circuits qualify.
• F38 close-couple direct drive; standard AR RK repair kits and service path.
• Nickel-plated and stainless head options available across the platform for chemical-duty operations.
• Ideal for fleet and municipal washdown, construction and agricultural equipment cleaning, service truck systems, and contractor rigs that refuse the flow-versus-pressure trade.