KYB MRH Series Five-Star Hydraulic Motor | MRH-200 MRH-500 MRH-750MAD

The MRH Series radial piston hydraulic motors (commonly known as “Five-Star Motors”) by Chengyuan Hydraulic are high-performance power components engineered to the exact technical standards of KYB (Kayaba). This series specifically targets premium replacements for MRH-200, MRH-500, and the mechanical-brake equipped MRH-750MAD.

Renowned for exceptional low-speed stability and high starting torque efficiency, Chengyuan ensures 100% original-place interchangeability regarding mounting flanges, shaft ends, and porting configurations. Every motor undergoes 100% simulated operational load testing, guaranteeing that pressure output and service life meet OEM standards in high-intensity applications such as injection molding, marine engineering, and heavy construction.

Technical Specifications :

• Compatible Series: KYB MRH Series (Radial Piston Motor)

• Core Models: MRH-200, MRH-500, MRH-750MAD

• Geometric Displacement:

  • MRH-200: 198 $cm^3/rev$

  • MRH-500: 492 $cm^3/rev$

  • MRH-750: 737 $cm^3/rev$

• Rated Operating Pressure: 21 MPa (210 bar)

• Peak Operating Pressure: 25 MPa (250 bar)

• Rated Output Torque: Up to 2400 Nm (for MRH-750)

• Maximum Speed: 150 – 300 rpm (depending on displacement)

• Minimum Steady Speed: 1 rpm (superior low-speed smoothness)

• Rotation: Bi-directional / Fixed displacement

• Brake Option: MAD suffix indicates integrated multi-disc mechanical brake.

Key Technical Advantages:

• Classic Five-Star Radial Architecture: Utilizing a star-arranged piston layout, hydraulic force is transmitted directly to the eccentric shaft via a connecting rod mechanism. This design minimizes mechanical friction, allowing for smooth operation at speeds as low as 1 rpm without “cogging.”

• High Starting Torque Efficiency: Due to precision-ground valve plates and optimized piston-bore fitting, Chengyuan’s MRH motors achieve a starting torque of over 90% of theoretical value. This is ideal for heavy-load startups and frequent reversing cycles.

• Heavy-Duty Bearing System: The bearing assembly is reinforced to handle high axial and radial loads. This allows the motor to directly drive heavy winch drums or agitator shafts without the need for additional external bearing supports.

• Integrated MAD Mechanical Brake: For the MRH-750MAD model, the integrated normally-closed multi-disc brake is hydraulically released, ensuring fail-safe braking during power loss—a critical feature for hoisting and traction equipment.

Application Areas:

• Injection Molding: Driving the pre-plasticizing screw.

• Marine & Port Machinery: Winches, slewing mechanisms, and deck cranes.

• Construction Engineering: Shield machine cutter head drives and rotary drilling rig power units.

Expert Maintenance Tips:

• Case Drain Pressure Management: The case drain line must be connected. Ensure the internal case pressure remains below 0.1 MPa; excessive backpressure will compromise the shaft seal and valve plate accuracy.

• Initial Bleeding Protocol: Fill the motor case with clean hydraulic oil through the highest drain port before the first run. Operate at low speed without load to bleed residual air, preventing cavitation damage to the pistons.

• Filtration Standards: A system filtration level of NAS 9 or ISO 4406 19/17/14 is recommended to protect the precision-engineered distribution interface of the five-star motor.