HMC045/S/45/20-SO3 Kawasaki Staffa Radial Piston Motor 737cc 250bar

Product Overview

The HMC045/S/45/20-SO3 is a low-speed high-torque (LSHT) radial piston hydraulic motor from the Kawasaki Staffa HMC series. The HMC series represents the iconic product line of the Staffa brand, featuring proven radial piston technology and widely deployed in hydraulic transmission systems for mobile machinery, marine engineering, and industrial equipment.

Kawasaki Staffa HMC series motors feature a dual displacement design with two pre-set displacements that can be hydraulically switched via a directional control valve while the motor is running. The HMC045, as a mid-range model in the series, delivers 737 cc/rev displacement, 250 bar rated pressure, 275 bar peak pressure, 2930 N.m maximum torque, and up to 80 kW continuous output power.

The HMC series covers displacements from HMC030 (492 cc/rev) to HMC325 (5326 cc/rev) across 7 frame sizes. The HMC045, with its high torque density, excellent starting torque, and smooth running characteristics, has become the preferred choice for marine anchor windlasses, injection molding machine screw drives, and other demanding applications.

Designed as a 100% interchangeable direct replacement for original Kawasaki Staffa HMC series motors, this product matches OEM specifications in mounting dimensions, porting interfaces, and performance characteristics. Every unit undergoes 100% simulated duty cycle testing prior to shipment, validating volumetric efficiency, mechanical efficiency, and sealing integrity under actual operating load conditions.

Technical Specifications

HMC045/S/45/20-SO3

• Model: HMC045/S/45/20-SO3

• Brand: Kawasaki Staffa Series

• Product Type: Dual Displacement Radial Piston Hydraulic Motor

• Max Displacement: 737 cm³/rev

• Min Displacement: 153 cm³/rev

• Rated Pressure: 250 bar (3,625 psi)

• Peak Pressure: 275 bar (4,000 psi)

• Max Torque: 2930 N.m (2,160 lbf ft)

• Rated Torque: 1965 lb-ft ≈ 2664 N.m

• Continuous Output Power: 80 kW (108 hp)

• Maximum Speed: 450 rpm

• Minimum Speed: 600 rpm

• Control Type: Hydraulic pilot control, dual displacement switching

• Rotation Direction: Reversible

• Weight: Approx. 150 kg

• Circuit Type: Open circuit / Closed circuit

• Shaft Type: S = 17-tooth splined shaft, BS 3550 standard

• Port Configuration: SO3 = Staffa 3″ 6-bolt flange (UNF)

HMC Series – Full Model Range

• Series Name: Kawasaki Staffa HMC Dual Displacement Radial Piston Motor

• Frame Sizes: HMC030, HMC045, HMC080, HMC125, HMC200, HMC270, HMC325

• Displacement Range: 492 – 5326 cc/rev

• Rated Pressure: 250 bar (3,625 psi)

• Peak Pressure: 275 bar (4,000 psi)

• Control Type: Dual displacement hydraulic switching (switchable while running)

HMC080

• Max Displacement: 737 cc/rev

• Min Displacement: 153 cc/rev

• Rated Pressure: 250 bar

• Peak Pressure: 275 bar

• Maximum Speed: 450 rpm

• Weight: 150 kg

HMC125

• Max Displacement: 2048 cc/rev

• Min Displacement: 164 cc/rev

• Rated Pressure: 250 bar

• Peak Pressure: 275 bar

• Maximum Speed: 190 rpm

• Weight: 234 kg

HMC200

• Max Displacement: 3080 cc/rev

• Min Displacement: 160 cc/rev

• Rated Pressure: 250 bar

• Peak Pressure: 275 bar

• Maximum Speed: 175 rpm

• Max Torque: 12800 N.m

• Continuous Output Power: 174 kW

• Weight: 282 kg

HMC270

• Max Displacement: 4588 cc/rev

• Min Displacement: 328 cc/rev

• Rated Pressure: 250 bar

• Peak Pressure: 275 bar

• Maximum Speed: 120 rpm

• Weight: 450 kg

HMC325

• Max Displacement: 5326 cc/rev

• Min Displacement: 1557 cc/rev

• Rated Pressure: 250 bar

• Peak Pressure: 275 bar

• Maximum Speed: 100 rpm

• Max Torque: 20104 N.m

• Weight: 460 kg

Key Technical Advantages

1. Dual Displacement Design – Switchable While Running

The HMC series features a unique dual displacement design with two pre-set displacements that can be hydraulically switched via a directional control valve while the motor is running. This enables the motor to flexibly transition between low-speed high-torque and high-speed operation modes, significantly improving overall machine productivity and application adaptability. Displacement switching is rapid—the HMC045 high/low displacement change takes just 0.25 seconds with a switching flow requirement of 15 L/min.

2. Hydrostatic Balancing Technology – High Efficiency with Superior Starting Torque

Kawasaki Staffa radial piston motors employ hydrostatic balancing techniques that deliver high efficiency combined with excellent breakout torque. Superior starting torque and smooth running capability ensure outstanding performance under heavy-load start-up and low-speed operating conditions.

3. High Pressure Rating with High Torque Output

The HMC series delivers rated pressure of 250 bar and peak pressure of 275 bar. The HMC045 delivers maximum torque up to 2930 N.m with continuous output power of 80 kW. The HMC200 delivers maximum torque up to 12800 N.m with continuous output power of 174 kW. The HMC325 delivers maximum torque up to 20104 N.m. This high pressure and torque capability meets the most demanding heavy machinery applications.

4. 100% Interchangeability – Zero-Modification Drop-In Replacement

Manufactured to exact OEM mounting dimensions, porting specifications, and performance standards, this motor achieves 100% interchangeability with original Kawasaki Staffa HMC series units. No machine modifications are required—simply replace and resume operation, minimizing downtime and reducing maintenance costs.

5. 100% Simulated Duty Cycle Testing for Extreme Environment Reliability

Every motor undergoes 100% simulated duty cycle testing before shipment, validating performance under rated pressure (250 bar) and peak pressure (275 bar) conditions—ensuring long-term reliability in demanding marine, mining, construction, and industrial applications.

6. Robust Radial Piston Construction for Extended Service Life

Staffa radial piston motors feature a simple yet robust construction where radial pistons act directly on an eccentric cam. This design minimizes moving parts, enhancing reliability and extending service life. The HMC series is equipped with high-capacity bearings suitable for applications requiring high lifetime, high power/pressure, and high external loads.

7. Extensive Configuration Options with Scalability

The HMC series offers multiple shaft options (splined, parallel key, DIN 5480 splined, etc.), various port configurations (SO3 6-bolt flange, etc.), and multiple mounting interface options. Interfaces can be customized to match competitor specifications for seamless equipment upgrades and maintenance. Optional speed sensors, integrated brakes, and gearboxes are available to extend the torque range.

Application Areas

• Marine Industry: Anchor windlass drives, deck machinery, winch drives

• Injection Molding Machinery: Screw drives

• Construction Equipment: Excavator travel drives, tracked travel mechanism drives

• Mining Equipment: Mining and construction machinery hydraulic drives

• Heavy Mobile Machinery: Large travel drive systems

• Offshore Engineering: Offshore platform equipment hydraulic drives

• Industrial Equipment: Heavy industrial machinery hydraulic transmissions

Expert Maintenance Tips

1. Pre-Installation Preparation: Before using the HMC series motor, read and understand the complete Kawasaki Staffa technical manual. For first commissioning, fill the motor housing with hydraulic fluid using a filling unit with filtration not less than 10 µm. Never operate the motor without fluid.

2. Crankcase Drain Orientation: HMC series motors are sensitive to housing backpressure. Ensure the crankcase drain line is unobstructed and correctly positioned. The drain line must return to a separate oil tank to prevent seal damage from excessive housing pressure.

3. Cooling Flow Requirements: HMC series motors require adequate cooling flow during continuous high-power operation. Ensure the system design meets the motor’s cooling flow requirements to prevent overheating and internal wear.

4. Boost Pressure: For closed-circuit applications, ensure adequate boost pressure to guarantee proper suction and lubrication during high-speed operation.

5. Oil Cleanliness Control: Recommended system filtration not less than ISO 4406 18/13. Regular oil analysis is recommended with filter change intervals adjusted based on contamination levels.

6. Start-Up Procedure: Follow the correct start-up procedure as specified in the instruction manual before first operation, ensuring the motor is properly lubricated and free of air.

7. Regular Inspection Schedule: Regular inspection of the hydraulic system and motor is recommended. Check hydraulic fluid level daily and monitor operating temperature, noise levels, and case drain flow regularly. Abnormal increases may indicate internal wear or seal degradation.