46M-185A-1C20R Hydraulic Motor | Vickers M Series Vane

Product Overview

The M Series hydraulic motor is Eaton Vickers’ classic high-speed, high-pressure fixed-displacement vane motor, spanning multiple sub-families including 25M, 26M, 35M, 36M, 45M, 46M, 50M, and 51M, with displacements ranging from 43.9 to 317 cm³/rev and 12 torque ratings from 42 to 300 lb-in/100 psi. Featuring a balanced vane design, the M Series is a proven design that has been operating in the field for decades. These motors start out with high efficiencies and operate at those levels throughout the life of the motor — inherent to this vane motor design. The M Series operates from as low as 100 rpm to as high as 3000 rpm at maximum pressures, with the bi-rotational design lending itself to quick reversal motion. They can be stalled at as high as 65% of maximum pressure rating at 1200 rpm without damage.

The 46M-185A-1C20R is the heavy-duty bearing version (“6” indicates heavy-duty bearing) of the 46M sub-series, with a displacement of 193.2 cm³/rev (11.79 in³/rev), torque rating of 185 lb-in/100 psi, maximum continuous pressure of 172 bar (2500 PSI), maximum speed of 3000-4000 rpm, and maximum continuous flow of 61.3-61.4 GPM. It features an SAE C 2-bolt flange, 1-1/4 inch 14-tooth splined shaft (1-1/4 inch keyed shaft optional), and weighs approximately 39 kg (85 lb). The internal rotating parts are self-contained in a cartridge kit, making this motor easily field serviceable. In most cases the motor can stay in place while the ring, rotor, and vanes are replaced with new, and port orientation adjustments can be done in the field.

This product is a drop-in interchange replacement for genuine Eaton Vickers 46M-185A-1C20R hydraulic motors. Mounting flange (SAE C 2-bolt), shaft extension (1-1/4 inch 14-tooth splined or keyed), port configurations, and case drain port location are dimensionally identical to OEM specifications, enabling direct replacement without hydraulic circuit or mounting modification. Every motor is subjected to 100% simulated actual-load testing before shipment, ensuring volumetric efficiency, output torque, and sealing performance meet OEM technical standards.

OEM Part Number Coverage:

• Primary Models: 46M-185A-1C20R, 46M185A1C20, 46M-185-A-1C20, 45M185A-1A20

• 25M Series: 25M42A-1C20, 25M42A-11C20, 25M42A2 1C20, 25M30A-1C20, 25M55A-1C20, 25M65A-1C20

• 45M/46M Series: 45M130A, 45M155A, 45M185A, 46M130A, 46M155A, 46M185A

• 50M Series: 50M220A, 50M255A, 50M300A, 50M255A-11A20-114

• Both heavy-duty bearing models (26M/36M/46M/51M) and standard bearing models (25M/35M/45M/50M) are covered

Technical Specifications 

46M-185A-1C20R Core Specifications:

• Model Code: 46M-185A-1C20R

• Series: Eaton Vickers M Series (46M sub-series, heavy-duty bearing version)

• Product Type: High-speed high-pressure fixed-displacement vane motor, bi-rotational, externally drained

• Ring Capacity Torque Rating: 185 lb-in/100 psi (approx. 20.9 Nm/6.9 bar)

• Geometric displacement: 193.2 cm³/rev (11.79 in³/rev)

• Max continuous pressure: 172 bar (2500 PSI)

• Max speed: 3000 rpm @ 172 bar (at max pressure); 4000 rpm @ reduced pressure

• Max continuous flow: 61.3–61.4 GPM (approx. 232 L/min)

• Max continuous torque: Approx. 502 Nm (4450 lb-in) @ max pressure

• Theoretical torque: 20.9 Nm/6.9 bar (185 lb-in/100 psi)

• Control type: Fixed displacement, balanced 12-vane cartridge design

• Mounting flange: SAE C 2-bolt

• Shaft type: 1-1/4 inch 14-tooth splined shaft (standard), 1-1/4 inch keyed shaft (optional), 5/16 inch key

• Port connections: SAE 4-bolt flange

• Rotation: Bi-rotational

• Seal material: Buna-N (NBR) standard

• Bearings: Heavy-duty bearings (standard bearing version is 45M)

• Weight: Approx. 39 kg (85 lb)

• Recommended oil viscosity: 70 SUS

25M42A-1C20 Core Specifications:

• Geometric displacement: 43.9 cm³/rev (2.68 in³/rev)

• Torque rating: 42 lb-in/100 psi (approx. 4.7 Nm/6.9 bar)

• Max continuous pressure: 172 bar (2500 PSI)

• Max speed: 3000 rpm @ max pressure; 4000 rpm @ reduced pressure

• Max flow: 13.9 GPM

• Mounting flange: SAE B 2-bolt

• Shaft type: 7/8 inch 13-tooth splined (standard), 7/8 inch keyed (optional), 3/16 inch key

• Weight: Approx. 18 kg (40 lb)

45M185A-1A20 Core Specifications:

• Geometric displacement: 193.2 cm³/rev (11.79 in³/rev)

• Torque rating: 185 lb-in/100 psi

• Max continuous pressure: 172 bar (2500 PSI)

• Max speed: 3000–4000 rpm

• Max flow: 61.3 GPM

• Mounting flange: SAE C 2-bolt

• Shaft type: 1-1/4 inch 14-tooth splined or 1-1/4 inch keyed

• Bearings: Standard bearings

• Weight: Approx. 39 kg (85 lb)

50M220A Core Specifications:

• Geometric displacement: Approx. 344 ml/r (approx. 21.0 in³/rev)

• Torque rating: 220 lb-in/100 psi (approx. 24.9 Nm/6.9 bar)

• Max continuous pressure: 155 bar (2250 PSI)

• Max speed: 2400 rpm @ 2500 PSI

• Max flow: 73.3–85.0 GPM

• Mounting flange: SAE D 2-bolt

• Shaft type: 1-3/4 inch 13-tooth splined (standard), 1-3/4 inch keyed (optional), 7/16 inch key

• Weight: Approx. 73 kg (160 lb)

50M255A-11A20 Core Specifications:

• Geometric displacement: 401 ml/r (16.36 in³/rev)

• Torque rating: 255 lb-in/100 psi (approx. 28.8 Nm/6.9 bar)

• Max continuous pressure: 155 bar (2250 PSI)

• Max speed: 2200–3200 rpm

• Max flow: 85 GPM

• Mounting flange: SAE D 2-bolt (some configurations SAE C 2-bolt)

• Shaft type: 1-3/4 inch 13-tooth splined

• Weight: Approx. 73 kg (160 lb)

M Series Full Model Displacement & Torque Reference:

• 25M: Torque ratings 42/55/65 lb-in/100 psi; Displacements 43.9/57.7/68.7 cm³/rev; Max speed 3000–4000 rpm

• 35M: Torque ratings 80/95/115 lb-in/100 psi; Displacements 82.9/98.0/118.7 cm³/rev

• 45M: Torque ratings 130/155/185 lb-in/100 psi; Displacements 138.0/163.2/193.2 cm³/rev; Max speed 3000–4000 rpm

• 50M: Torque ratings 220/255/300 lb-in/100 psi; Displacements approx. 344/401/approx. 470 cm³/rev; Max speed 2200–3200 rpm

General Configuration Parameters (M Series):

• Control type: Fixed displacement, balanced vane design

• Mounting flange: SAE B/C/D 2-bolt or SAE 4-bolt flange

• Shaft options: Keyed or splined (SAE standard)

• Port connections: SAE 4-bolt flange

• Rotation: Bi-rotational design

• Seal material: Buna-N (NBR) standard

• Bearings: Standard bearings (25M/35M/45M/50M) or heavy-duty bearings (26M/36M/46M/51M)

• Operating fluid: Mineral-based hydraulic oil

• Recommended oil viscosity: 70 SUS

• Operating temperature range: -30°C to +90°C

Key Technical Advantages

1. Balanced Vane Design with High Volumetric Efficiency
The M Series features a balanced vane design. The vanes, rotor, and cam ring are made of hardened high alloy steels, while the cast iron port plate and end cap are chemically etched to offer a fine crystalline surface allowing better lubrication at start-up. The motors start out with high efficiencies and operate at those levels throughout the life of the motor — inherent in this vane motor design. Double-lip vanes reduce sensitivity to fluid pollution, and the fully pressure-balanced concept increases motor lifetime over its full speed range.

2. High Speed and High Pressure Combined Performance
The M Series operates at pressures up to 172 bar (2500 PSI) and speeds up to 3000 rpm at maximum pressures, with speeds up to 4000 rpm achievable at reduced system pressures. The 25M Series delivers a maximum flow of 13.9 GPM, the 45M Series 61.3 GPM, and the 50M Series 85 GPM. The motor design can operate at as low as 100 rpm to as high as 3000 rpm at maximum pressures, and can run at faster speeds as system pressures decrease.

3. Quick Reversal and High Stall Resistance
The bi-rotational design of the M Series lends itself to quick reversal motion. They can be stalled at as high as 65% of maximum pressure rating at 1200 rpm without damage. This characteristic makes the M Series ideal for applications requiring frequent reversals and tolerance of shock loads. Because both ports can be pressurized at the same time, the M Series is perfect for multiple motors connected in series.

4. Field Serviceability with Cartridge Interchangeability
The internal rotating parts of the M Series are self-contained in a cartridge kit, making this motor easily field serviceable. In most cases, the motor can stay in place while the ring, rotor, and vanes are replaced with new parts. Port orientation adjustments can also be done in the field. The heavy-duty bearing versions (26M/36M/46M/51M) allow for indirect drive options such as gears, belts, and pulleys. The series offers 12 torque ratings and multiple displacement options, allowing users to select the optimal model for their specific operating conditions.

Application Areas

• Construction Machinery (Core Application): Excavator swing drive, loader travel drive, crane swing mechanism, road roller drum drive

• Mining Equipment: Mine winch drive, drill feed mechanism, crusher drive

• Marine & Offshore: Deck winch drive, anchor windlass drive, steering gear drive

• Industrial Equipment: Mixer drive, shredder drive, compressor drive, generator drive, test bench drive

• Material Handling: Conveyor drive drum, heavy-duty forklift drive, stacker drive

• Agricultural Machinery: Combine harvester drive, large tractor hydraulic drive

Expert Maintenance Tips

Pre-Installation Preparation:
Clean all ports and mounting flanges with lint-free wipes or clean compressed air before installation. Verify O-ring integrity. The 46M-185A-1C20R uses an SAE C 2-bolt flange — confirm the flange specification matches the system before installation. Torque mounting bolts in a diagonal sequence over 2–3 passes. After installation, manually rotate the output shaft to confirm free and smooth rotation without binding. M Series motors are designed for coaxial drives where no axial or radial forces act on the shaft; contact Parker for special application cases.

Drain Port Management:
The M Series is an externally drained motor — the case drain port must be connected to a drain line routed separately back to the reservoir with the end submerged below the oil level. Drain line back pressure must not exceed 2 bar; excessive back pressure will damage the shaft seal. For multi-motor series connections, ensure proper case pressure distribution.

Hydraulic Fluid Management:
Use anti-wear hydraulic oil with ISO VG 46 or ISO VG 68 viscosity grade (corresponding to the 70 SUS recommended viscosity). Maintain fluid cleanliness at ISO 18/16/13 or NAS Class 8 minimum. Operating temperature should not exceed 80°C. Internal parts are lubricated by the operating fluid itself; therefore, preventive maintenance is limited to keeping the fluid clean and maintaining an acceptable viscosity range. System filters should be replaced frequently.

Cartridge Service and Replacement:
The cam ring, rotor, vanes, and springs of the M Series are self-contained in a cartridge kit. When performance restoration is required, the cartridge can be replaced directly without disassembling the entire motor. After cartridge replacement, port orientation should be re-adjusted to match system piping. When installing a new cartridge, verify all vanes are properly seated and spring preload is uniform.

Periodic Inspection:
Check volumetric efficiency every 500 operating hours or quarterly. Test method: lock the output shaft at rated pressure and measure leakage flow. If leakage exceeds 10% of rated flow, internal wear has entered an accelerated phase — schedule service or replacement. Also inspect shaft seals for seepage and heavy-duty bearings for abnormal noise or vibration.