ME350BP Eaton Vickers Hydraulic Motor 350cc 27.5MPa LSHT

Product Overview

The ME350BP is a low-speed high-torque (LSHT) axial piston hydraulic motor built on the Eaton/Vickers DOWMAX ME series platform, in the ME350B displacement size (350 cm³/rev). The motor features an opposed-piston double swash plate design, specifically engineered for hydrostatic drives under low-speed heavy-load conditions, delivering optimal performance in the low-speed range.

The DOWMAX ME series motor is renowned for its exceptional low-speed performance — the multiple opposed pistons and double swash plate design enable smooth rotation at speeds down to 1 rpm without stick-slip or speed pulsation. The ME350BP offers a rated pressure of 27.5 MPa, peak pressure of 31.9 MPa, rated torque of 1536 N·m, rated speed of 660 rpm, maximum speed of 800 rpm, maximum power of 129 HP (106 kW), and weight of approximately 60 kg (62 kg with configuration modules). The ME series is available in 13 displacement sizes from 99 to 4097 cm³/rev, covering a wide range of application requirements.

The model code ME350BP decodes as follows: ME designates the DOWMAX standard motor series, 350 is the displacement size (350 cm³/rev), B is the third design change code, P is the JIS standard splined shaft configuration, and B is the special port type (for counterbalance valve mounting). The motor features a fixed displacement design with a pressure-compensated port plate, eliminating the need for variable adjustment mechanisms and offering simple construction with low maintenance requirements.

Engineered as a form-fit-function replacement for original Eaton/Vickers ME350BP series motors, this model maintains identical mounting flange dimensions, shaft specifications, and port locations, enabling drop-in interchangeability without modification to the host machine’s mounting interface or hydraulic circuit. Each unit undergoes 100% simulated load testing prior to shipment, validating output torque and volumetric efficiency against original specifications.

Technical Specifications 

• Model: ME350BP

• Series: Eaton/Vickers DOWMAX ME Series

• Motor Type: Opposed-piston double swash plate axial piston motor (LSHT)

• Design Feature: Double swash plate, multiple opposed pistons, pressure-compensated port plate

• Displacement: 350 cm³/rev (21.36 in³/rev)

• Rated Pressure: 27.5 MPa (280 kgf/cm² / 3,989 PSI)

• Peak Pressure: 31.9 MPa (325 kgf/cm² / 4,626 PSI)

• Rated Torque: 1536 N·m (1133 lb-ft)

• Rated Speed: 660 rpm

• Maximum Speed: 800 rpm

• Maximum Output Power: 106 kW (144 HP)

• Minimum Smooth Operating Speed: 1 rpm

• Rotation: Clockwise / Counter-clockwise / Bi-directional

• Shaft Type: P — JIS standard splined shaft

• Port Type: B — Special port (for counterbalance valve mounting)

• Seal Material: NBR standard; Viton optional

• Mounting: Flange mounting

• Weight (approx.): 60–62 kg (132–137 lb)

• Optional Features: Speed pickup system, counterbalance valve, flushing valve

Key Technical Advantages

1. Opposed-Piston Double Swash Plate Design with Superior Low-Speed Performance

The ME350BP employs Eaton DOWMAX’s unique opposed-piston double swash plate design, with multiple pistons symmetrically arranged on both sides of the swash plate, effectively balancing axial forces within the rotating group and significantly reducing bearing loads. This configuration enables smooth operation at speeds as low as 1 rpm without stick-slip or speed pulsation. The special slipper design further reduces friction between pistons and the swash plate, delivering high starting efficiency and overall efficiency in the low-speed range.

2. Pressure-Compensated Port Plate with Thermal Shock Resistance

The motor features a pressure-compensated flat port plate design, where the port plate adaptively conforms to the cylinder block face under pressure, ensuring sealing performance at high pressures and speeds. This design gives the motor excellent thermal shock resistance, with good starting performance in cold environments and the ability to start with hot oil, preventing leakage and efficiency loss caused by port plate deformation during rapid temperature changes.

3. High Power Density with Compact Construction

The ME350BP delivers a maximum power output of 129 HP and rated torque of 1536 N·m at a displacement of 350 cm³/rev, offering an excellent power-to-weight ratio. The motor features a compact structure and easy installation, suitable for applications with limited installation space. The DOWMAX ME series offers 13 displacement sizes (99 to 4097 cm³/rev), covering needs from compact to heavy-duty drives, with the same mounting interface accommodating multiple displacement options for easy system integration and future upgrades.

4. Proven Reliability in Marine and Heavy-Duty Industrial Applications

DOWMAX ME series motors have mature applications in demanding conditions such as ship hatch covers, deck cranes, drilling rigs, port equipment, and tunnel boring equipment, validated through long-term field operation. The ME350BP’s rated pressure of 27.5 MPa and peak pressure of 31.9 MPa provide ample system pressure margin. An optional speed pickup system supports closed-loop speed control for precision drive requirements. The motor accommodates substantial radial and axial loads, suitable for direct belt, gear, or sprocket drives.

Application Areas

• Marine & Offshore: Ship hatch cover motors, deck cranes, windlasses, winches, hatch cover drive mechanisms

• Drilling Equipment: Directional drilling rigs, drill power heads, rotary drilling rigs

• Construction Machinery: Tunnel boring equipment, excavator swing drives, port equipment

• Metallurgy & Heavy Industry: Steel mill drive systems, heavy-duty rotary actuators

• Industrial Drives: Industrial drive systems, gate and dam drives

The DOWMAX ME series motor is particularly suited for heavy-duty applications requiring smooth low-speed operation and high starting torque, with extensive use in the marine and drilling industries.

Expert Maintenance Tips

1. Shaft Alignment Requirements: The motor output shaft accommodates combined radial and axial loads. During installation, ensure the coaxiality deviation between the motor shaft and drive-end coupling does not exceed 0.05 mm. Excessive radial forces will accelerate bearing wear and shaft seal aging. When installing the P-type JIS splined shaft, ensure the spline mating surfaces are free of burrs and damage.

2. Hydraulic Fluid Cleanliness Control: Maintain hydraulic fluid cleanliness at NAS Level 9 or better. Replace hydraulic fluid and filter elements every 1,000 operating hours or annually, with filter element filtration accuracy no less than 10 μm. Contaminant particles accelerate port plate and piston pair wear, degrading volumetric efficiency.

3. Thermal Shock Management: The motor offers excellent thermal shock resistance and allows hot oil starting in cold environments. During cold starts, run at low pressure (10 MPa) under no load for 10 minutes until case temperature is uniform before gradually applying load, avoiding excessive thermal stress on piston pairs.

4. Counterbalance Valve and Back Pressure Control: This model features a B-type special port design (for counterbalance valve mounting). When the system is equipped with a counterbalance valve, ensure the return back pressure does not exceed the motor’s allowable back pressure. The drain port must be connected separately to the reservoir with back pressure not exceeding 0.5 MPa.

5. Restart After Extended Storage: For motors stored over 6 months, manually rotate the shaft 2–3 revolutions to confirm free rotation, then run at low pressure under no load for 10 minutes, confirming normal case temperature and leakage before gradually applying load.