HDS 47 S OMFB Bent Axis Piston Motor 47.13cc 350bar

Product Overview

The HDS 47 S is a mid-displacement bent-axis axial piston motor from the OMFB (O.M.F.B. S.p.A. Hydraulic Components) HDS series, OMFB part number 601-001-10479 (old code 108-015-04742). The motor employs a bent-axis axial piston design with a 7-piston rotary group, suitable for open circuit hydraulic systems, with a continuous working pressure of 350 bar (5,080 psi), peak pressure of 400 bar (5,800 psi), geometric displacement of 47.13 cm³/rev, continuous speed of 1,900 rpm, intermittent speed of 2,700 rpm, maximum flow of approximately 70.6 L/min (@1500 rpm), and weight of approximately 12.28 kg (ISO flange version).

The core design philosophy of the HDS series motors revolves around low noise, high power density, and long service life. OMFB has significantly optimized the mechanical engagement between the cylinder block and drive gear through an improved internal gear tooth machining method, reducing noise levels to extremely low levels while maintaining maximum performance. The compact cast iron body offers reduced dimensions with high resistance to pressure peaks. The 7-piston configuration ensures uniform bearing load distribution, further reducing flow pulsation and operating noise.

The model code decodes as: “HDS” = HDS series bent-axis axial piston motor, “47” = 47.13 cm³/rev displacement frame, “S” = left-hand (counterclockwise) rotation (viewed from shaft end), also designated as “L” (Left) in some documentation. This model can be directly interchanged with equivalent products from Parker F1, Rexroth A17FO, and Sunfab SCP.

Series-Related Models: The OMFB HDS/MDS series covers HDS 12, HDS 17, HDS 25, HDS 34, HDS 40, HDS 47, HDS 55, HDS 64, HDS 84, HDS 108, HDS 130, and MDS 80, MDS 130 frame sizes. Among these, the MDS-80 is a 5-piston mid-displacement variant with 84.33 cm³/rev displacement, 250/300 bar maximum pressure, 1,800 rpm continuous speed, and 120 L/min flow (@1500 rpm). The HDS series covers displacements from 12.62 cm³/rev to 130 cm³/rev, with a uniform continuous pressure of 350 bar and peak pressure of 400 bar.

The motor offers complete interchangeability: ISO 7653 4-hole flange (80×80 mm), DIN 5462 8×32×36 splined shaft, G 3/4″ pressure port, and G 1-1/4″ suction port are identical to the original OMFB specification, enabling drop-in replacement without hose or bracket modification. Every unit undergoes 100% simulated duty-cycle testing before shipment.

Technical Specifications 

HDS 47 S (Primary Model)

• Model: HDS 47 S

• OMFB Part Number: 601-001-10479

• Old Code: 108-015-04742

• Brand Series: OMFB HDS Series

• Motor Type: Bent-axis axial piston motor, 7-piston rotary group

• Geometric Displacement: 47.13 cm³/rev (2.88 in³/rev)

• Continuous Working Pressure: 350 bar (5,080 psi)

• Peak Pressure: 400 bar (5,800 psi)

• Continuous Speed: 1,900 rpm

• Intermittent Speed: 2,700 rpm

• Maximum Flow (@1500 rpm): 70.61 L/min

• Rotation: Left-hand (counterclockwise, S configuration)

• Mounting Flange: ISO 7653 4-hole flange, 80×80 mm

• Shaft Type: DIN 5462 8×32×36 splined shaft

• Pressure Port: G 3/4″ (BSP)

• Suction Port: G 1-1/4″ (BSP)

• Weight: Approximately 12.28 kg (ISO flange version)

• Housing Material: Nodular cast iron

• Seal Material: FKM (Fluoroelastomer)

• Operating Temperature Range: -40°C to +140°C (special seal configuration)

• Piston Count: 7

HDS Series Other Displacement Sizes (Series Reference)

• HDS 12: Displacement 12.62 cm³/rev, continuous pressure 350 bar, peak pressure 400 bar, continuous speed 2,300 rpm, intermittent speed 3,000 rpm

• HDS 17: Displacement 16.98 cm³/rev, continuous pressure 350 bar, peak pressure 400 bar, continuous speed 2,300 rpm, intermittent speed 3,000 rpm

• HDS 25: Displacement 25.12 cm³/rev, continuous pressure 350 bar, peak pressure 400 bar, continuous speed 2,300 rpm, intermittent speed 3,000 rpm

• HDS 34: Displacement 33.80 cm³/rev, continuous pressure 350 bar, peak pressure 400 bar, continuous speed 2,300 rpm, intermittent speed 3,000 rpm

• HDS 40: Displacement 41.25 cm³/rev, continuous pressure 350 bar, peak pressure 400 bar, continuous speed 1,900 rpm, intermittent speed 2,700 rpm, flow 61.88 L/min (@1500 rpm)

• HDS 47: Displacement 47.13 cm³/rev, continuous pressure 350 bar, peak pressure 400 bar, continuous speed 1,900 rpm, intermittent speed 2,700 rpm, flow 70.61 L/min (@1500 rpm) (primary model)

• HDS 55: Displacement 56.70 cm³/rev, continuous pressure 350 bar, peak pressure 400 bar, continuous speed 1,900 rpm, intermittent speed 2,500 rpm

• HDS 64: Displacement 63.56 cm³/rev, continuous pressure 350 bar, peak pressure 400 bar, continuous speed 1,900 rpm, intermittent speed 2,700 rpm, flow 95.30 L/min (@1500 rpm)

• HDS 84: Displacement 84.33 cm³/rev, continuous pressure 350 bar, peak pressure 400 bar, continuous speed 1,500 rpm, intermittent speed 2,000 rpm

• HDS 108: Displacement 107.00 cm³/rev, continuous pressure 350 bar, peak pressure 400 bar, continuous speed 1,500 rpm, intermittent speed 2,000 rpm

• HDS 130: Displacement 131.60 cm³/rev, continuous pressure 350 bar, peak pressure 400 bar, continuous speed 1,500 rpm, intermittent speed 2,000 rpm

Note: HDS series parameters are compiled from OMFB official product catalogues and Salhydro publicly available technical data tables.

MDS-80 Mid-Displacement Variant (Series Reference)

• Model Frame: MDS-80

• Piston Count: 5

• Displacement: 84.33 cm³/rev

• Maximum Working Pressure: 250 bar (continuous) / 300 bar (peak)

• Continuous Speed: 1,800 rpm

• Intermittent Speed: 2,300 rpm

• Flow (@1500 rpm): 120.00 L/min

• Suction Port: G 1-1/4″

• Pressure Port: G 3/4″

• Features: 5-piston design, more compact structure than 7-piston version, suitable for medium displacement requirements

Key Technical Advantages

① 7-Piston Bent-Axis Design — Low Noise, Low Pulsation, High Bearing Life

The HDS 47 S utilizes OMFB‘s signature 7-piston bent-axis design. The 7-piston configuration is engineered to ensure uniform load distribution across the bearings while significantly reducing flow pulsation and operating noise. OMFB official documentation states that the 7-piston design is “the optimal solution to allow a more constant load on bearing and, consequently, a more fluent delivery and less pulsation”. Pistons are arranged at an angle to the drive shaft, contacting the drive plate through spherical ends to directly convert pressure into torque. Compared to swash plate designs, the bent-axis architecture achieves higher power density and more compact axial dimensions at equivalent displacement. The precision-lapped piston-to-bore surfaces maintain low internal leakage under high pressure.

② Nodular Cast Iron Housing and 3-Piece Construction — High Pressure Peak Resistance and Continuous Lubrication

The HDS 47 S employs a nodular cast iron housing with an exceptionally compact design. Nodular cast iron offers higher strength and toughness compared to conventional grey cast iron, enabling the housing to resist pressure peaks while reducing overall dimensions, accommodating up to 400 bar. The 3-piece construction design ensures continuous lubrication of the bearings during operation, preventing premature bearing failure caused by inadequate lubrication. Internal reinforcement ribbing further enhances overall rigidity, effectively resisting external shock loads in demanding mining and construction environments.

③ Tapered Roller Bearings and Hardened Drive Gear — High Load Capacity and Torque Transmission

The HDS 47 S output end employs tapered roller bearings capable of withstanding the greater axial and radial loads generated by high working pressures (up to 400 bar). The drive shaft is equipped with a hardened splined output shaft, enhancing resistance to torque transmitted from the PTO, effectively preventing spline wear and premature failure under frequent start-stop and load fluctuation conditions in truck PTO drive applications.

④ Reinforced FKM Seals and Wide Temperature Range — Adaptable to Demanding Environments

The HDS 47 S is equipped with reinforced FKM (fluoroelastomer) sealing components, allowing the motor to operate normally within a wide temperature range of -40°C to +140°C. FKM sealing material offers excellent high-temperature resistance, media compatibility, and compression set resistance, maintaining stable sealing performance in truck hydraulic systems, municipal sanitation vehicles, and other applications with significant temperature fluctuations. The optimized seal system design also enables the motor to withstand certain back pressures, suitable for flushing valve applications in closed or semi-closed circuits.

⑤ Broad Interchange Compatibility and Series Selection

The HDS 47 S’s standardized mounting interface (ISO 7653 4-hole flange, DIN 5462 splined shaft, BSP ports) allows direct replacement of equivalent OMFB original motors. OMFB officially confirms that the HDS 47 series can be installed as a replacement for Parker F1, Rexroth A17FO, Sunfab SCP, and other brand equivalents. The HDS/MDS series offers complete displacement coverage from 12.62 cm³/rev to 131.60 cm³/rev, enabling users to precisely select displacement size based on specific application torque, speed, and flow requirements.

Application Areas

• Trucks & Commercial Vehicles (Primary Application): Dump truck PTO drives, container curtain-side opening systems, cargo floor drives

• Mobile Cranes: Truck-mounted cranes, knuckle-boom crane hydraulic slew and hoist drives

• Municipal Sanitation Vehicles: Refuse compactors, sweepers, snow removal vehicle hydraulic systems

• Construction Machinery: Excavators (Komatsu PC200-8, CAT 320D, Hitachi ZX240-5, Volvo EC950F), loaders (JCB 3CX, CASE 570N, CAT 930M), cranes (Liebherr LTM 1050-3.1, Terex Demag AC 500-2)

• Agricultural Machinery: Tractors (John Deere 7730, New Holland T7.200, Fendt 718 Vario), combine harvesters (John Deere S670, New Holland CR 9060, Claas Lexion 600)

• Forestry Machinery: John Deere 1170G, Tigercat 740E, Caterpillar 527D harvesters and forwarders

• Industrial Transmission: Compact hydraulic transmission systems requiring high-pressure, low-noise open circuit hydraulic motors

Expert Maintenance Tips

Pre-Installation Inspection: Verify flatness and cleanliness of the ISO 7653 4-hole flange (80×80 mm) mating surface; check thread condition of mounting bolt holes. The DIN 5462 8×32×36 splined shaft-to-coupling or drive interface fit must conform to standards, avoiding interference fits that could damage the spline. The rotation direction of the HDS 47 series can be changed by turning the end section with the oil connections 180°; confirm the rotation direction configuration before installation according to system requirements. Use bolts of strength class 8.8 or higher, tightened in diagonal sequence to specified torque.

First Commissioning: The motor housing must be filled with clean hydraulic oil before initial start-up. Fill through the highest casing port until oil overflows from the level port. Dry starting causes metal-to-metal contact between piston-to-bore surfaces and the valve plate without lubrication, resulting in irreversible damage. For models equipped with a by-pass valve, confirm proper valve operation to ensure correct oil circuit switching during continuous pump rotation.

Fluid Cleanliness: Maintain system oil cleanliness at NAS 8 (ISO 4406 18/16/13) or better. The bent-axis piston motor‘s valve plate and piston pairs are sensitive to particulate contamination; excessive contamination accelerates wear and causes volumetric efficiency degradation. The HDS series employs nitrided steel and natural cast iron sliding surface pairing, offering good wear resistance under contaminated oil conditions, but long-term cleanliness control remains key to extending service life. Inspect return filter elements regularly and replace per the machine manufacturer’s recommended interval.

Scheduled Inspection: Check casing drain flow and output shaft spline wear every 500 operating hours. Under normal conditions, drain flow should remain stable; a sustained increase indicates accelerated wear of piston pairs or valve plate surfaces, and preventive maintenance should be scheduled. Also inspect FKM seals for signs of aging, hardening, or leakage; equipment operating under high-temperature conditions should have seal inspection intervals shortened.

Long-Term Storage Protection: If the motor will be idle for more than 3 months, fill the casing with rust-preventive hydraulic oil and manually rotate the shaft several turns monthly to prevent corrosion or adhesion on piston pairs and valve plate surfaces. Perform a no-load run-in before returning to service.