KYB MRH2 Series Dual Displacement Hydraulic Motor | MRH2-750 MRH2-1500 MRH2-4400 | Radial Piston Motor

The MRH2 Series by Chengyuan Hydraulic is a high-performance, Low-Speed High-Torque (LSHT) radial piston motor designed to meet the most demanding industrial requirements. Fully compatible with KYB (Kayaba) technical standards, these motors offer 100% original-place interchangeability. The standout feature is the “Dual Displacement” capability, allowing machinery to switch between two preset displacements seamlessly under load to optimize both speed and torque. Each MRH2 unit undergoes 100% simulated condition testing to ensure mechanical integrity and high efficiency under peak operating pressures.

Technical Specifications :

• Model Range: MRH2-750, MRH2-1500, MRH2-2200, MRH2-3150, MRH2-4400, MRH2-6200

• Displacement Range: $746\text{ cm}^3\text{/rev}$ to $6220\text{ cm}^3\text{/rev}$

• Max Rated Pressure: $25\text{ MPa (250 bar)}$

• Peak Pressure: $31.5\text{ MPa (315 bar / 4568 psi)}$

• Rated Torque: Up to $24,000\text{ N}\cdot\cdot\text{m}$ (depending on frame size)

• Speed Range: Stable from $\le 1\text{ rpm}$ up to $300\text{–}500\text{ rpm}$

• Control Method: Hydraulic pilot displacement switching / Fixed displacement

• Housing: High-strength ductile iron for maximum pressure containment and noise reduction

Key Technical Advantages:

• Heavy-Duty Radial Piston Design: Utilizing a robust radial piston layout and multi-lobe cam track, the MRH2 provides near-constant torque even at near-zero speeds, eliminating “low-speed crawl” issues.

• On-the-Fly Displacement Switching: The integrated pilot control valve allows for instantaneous switching between high-speed/low-torque and low-speed/high-torque modes without interrupting the work cycle.

• Enhanced Cavitation Resistance: Specialized materials for the connecting rods and slippers, combined with optimized lubrication channels, enhance the motor’s resilience against cavitation during rapid reversals or shock loads.

• Balanced Valve Distribution: The pressure-balanced distributor shaft significantly reduces friction and heat generation, maintaining a mechanical efficiency of over $90\%$ during continuous $25\text{ MPa}$ operation.

Application Areas:

• Construction Machinery: TBM cutterhead drives and rotary drilling rig power heads.

• Mining Machinery: Heavy-duty conveyor drives and mining crushers.

• Marine & Offshore: Constant tension winches, deck crane slewing drives, and anchor windlasses.

Expert Maintenance Tips:

• Case Filling: Before initial startup, fill the motor case with clean hydraulic fluid through the highest drain port to ensure the slipper-to-cam interface is lubricated.

• Backpressure Management: Maintain return line backpressure within recommended limits. Insufficient backpressure may cause the slipper to lift off the cam, leading to vibration and wear.

• Dedicated Drain Line: Always connect the case drain line directly to the reservoir. Ensure the drain line pressure remains below $0.3\text{ MPa}$ to prevent shaft seal failure.