HYD-RK2120HNB-DD Hydraulic Motor Pump | 5.5 GPM 2900 PSI Nickel

HYD-RK2120HNB-DD | Hydraulic Motor Pump | 5.5 GPM 2900 PSI | Nickel-Plated Head

HYD-RK2120HNB-DD Hydraulic Motor Pump pairs an Annovi Reverberi RK 21.20 H triplex plunger pump with a direct-coupled hydraulic motor, delivering 5.5 GPM (21 L/min) at up to 2900 PSI (200 bar) at 1450 RPM — the muscle configuration of the RK line, combining the high flow of the RK 21 frame with genuine 2900 PSI-class working pressure. The HNB designation marks its defining upgrade: a nickel-plated brass pump head that shrugs off the chemical attack, detergent exposure, and corrosive conditions that pit and erode standard brass heads over time.

Where the standard HYD-RK2115 tops out at 2200 PSI and the HYD-RK1520 delivers its 3000 PSI at only 4 GPM, the HYD-RK2120HNB-DD gives you both numbers at once — 40% more water than the 4 GPM class and full commercial cleaning pressure — for faster stripping of mud, grease, and buildup on construction, agricultural, and municipal equipment.

HYD-RK2120HNB-DD Specifications

• SKU: HYD-RK2120HNB-DD
• Configuration: Hydraulic motor + pump, direct-coupled drive
• Pump: Annovi Reverberi RK 21.20 H triplex plunger pump (228-series frame), nickel-plated brass head
• Flow Rate: 5.5 GPM (21 L/min)
• Maximum Discharge Pressure: 2900 PSI (200 bar)
• Rated Speed: 1450 RPM
• Pump Power Requirement: Approximately 10.5 HP (7.9 kW) at full duty
• Drive Interface: F38 close-couple flange (SAE A 82.55) — motor mounted on the pump centerline
• Pump Inlet Ports (2): 1/2″ F
• Pump Discharge Ports (2): 3/8″ F
• Maximum Fluid Temperature: 140°F
• Head Material: Nickel-plated brass with stainless-steel wet-end components
• Plungers: One-piece ceramic

Why the Nickel-Plated Head Matters

Standard brass holds up well in clean, cold water — but add aggressive detergents, sanitation chemistry, softwash mixes, fertilizer residue, or salt-air coastal duty, and brass slowly pits, erodes, and de-zincifies at the valve seats and sealing surfaces. Nickel plating puts a hard, chemically resistant barrier over every wetted brass surface, extending head life dramatically in exactly the applications that kill standard pumps: livestock and food-plant sanitation, marine and dock washdown, de-icing support, agricultural chemical environments, and fleet operations running strong detergent programs. If your washdown chemistry is more than soap and water, the HYD-RK2120HNB-DD is the RK package specified for the job.

Hydraulic Supply Requirements

The HYD-RK2120HNB-DD demands a stronger circuit than the smaller RK packages: plan on approximately 8 GPM (31 L/min) of continuous oil flow at working pressure approaching 2,900 PSI — roughly 13 hydraulic horsepower at the full duty point, consistent with AR’s published pairing for the adjacent RK 21.21 model (198 bar at 31 L/min on the 19cc gear motor). Standard-flow skid steer and truck auxiliary circuits meet the flow easily; the pressure side is what to verify, since some circuits relieve below 2,900 PSI and will cap the water pressure accordingly. Keep the return line short and low-restriction back to tank, specify return filtration, and provide oil cooling for extended continuous-duty washing. If available flow runs slightly below spec, the HYD-RK2120HNB-DD runs proportionally slower — full rated water pressure still requires full supply pressure at the motor. Call WSHPWR with your machine’s auxiliary flow, pressure, and relief setting and we will confirm the match before you order.

Direct-Drive Advantages

The HYD-RK2120HNB-DD uses AR’s F38 close-couple architecture: motor and pump share one centerline inside a rigid flange interface, eliminating belts, pulleys, guards, and couplers along with their alignment drift and maintenance. The result is minimal side loading on bearings and seals, low vibration, cleaning performance independent of host engine speed, and a footprint compact enough for service bodies, wash skids, and tight OEM layouts.

Heavy-Duty RK-Series Construction

Beneath the nickel plating, the RK 21.20 H carries the proven 228-series architecture: one-piece ceramic plungers for heat dissipation and abrasion resistance, a pressed high-strength steel crankshaft on oversized bearings, and a die-cast aluminum crankcase with oil sight glass. Intake and delivery valves sit behind service plugs in the head, so inspection and replacement happen without dismounting the HYD-RK2120HNB-DD from the machine.

Installation & Operation Notes

Mount the assembly horizontally and confirm hydraulic motor rotation before commissioning. Keep suction plumbing short and unrestricted with flooded suction preferred, pair the discharge with a properly sized unloader set against your working pressure, and choose nozzle orifices for the 5.5 GPM duty point — undersized nozzles from 4 GPM systems will drive the unloader into constant bypass. Flush the system with clean water after chemical injection sessions to maximize the nickel head’s service life, check crankcase oil at the sight glass before first start, and winterize before cold-weather storage.

Quality Assurance & Maintenance

Every HYD-RK2120HNB-DD is built around a factory-tested Annovi Reverberi pump verified for flow rate, pressure stability, and vibration before shipment. Routine maintenance follows the standard RK pattern — scheduled pump oil changes, seal inspection, and periodic valve checks with standard AR repair kits — and the nickel-plated head extends the interval between valve and seat service in chemical-heavy duty.

HYD-RK2120HNB-DD Key Features & Applications

• 5.5 GPM at 2900 PSI, 1450 RPM — the highest flow-and-pressure combination in the RK package line.
• Nickel-plated brass head resists detergents, sanitation chemistry, salt air, and corrosive washdown environments.
• Direct-coupled hydraulic motor on the F38 flange — no belts, pulleys, or couplers to maintain.
• Requires approximately 8 GPM of hydraulic flow at up to ~2,900 PSI; verify your circuit relief setting.
• Ceramic plungers, stainless wet-end components, and serviceable valve plugs for continuous duty.
• Ideal for livestock and food-plant sanitation, marine and dock washdown, agricultural chemical environments, softwash support, and fleet detergent programs.