Rexroth A2F / A2FM Bent Axis Fixed Displacement Hydraulic Motor: The Complete Guide to High-Efficiency Rotary Power, OEM Replacements, and Spare Parts for Construction, Mining, and Industrial Drives in 2026

Author: Elephant Fluid Power Co., Ltd. | Updated: July 14, 2026 | Reading Time: 20 minutes

Quick Answer: If your equipment requires a high-efficiency, high-pressure hydraulic motor for concrete mixer truck agitators, winch drives, travel drives, swing drives, crane hoists, or mining equipment, the Rexroth A2F / A2FM bent axis fixed displacement hydraulic motor is the industry benchmark. Featuring a unique bent-axis design that delivers 92-96% total efficiency, over 95% starting torque, and 400 bar nominal pressure (450 bar peak) across 22 displacement sizes from 5 to 1,000 cm³, the A2FM is the most widely deployed fixed-displacement bent-axis motor in the world. Elephant Fluid Power Co., Ltd. manufactures complete A2F and A2FM motors in all sizes and over 1,300 types of 100% interchangeable spare parts — cylinder blocks, piston assemblies, spherical valve plates, drive shafts, seal kits, and rotating groups — delivering OEM-equivalent performance at 50-75% lower cost with same-day shipping from stock. With nearly 20 years of manufacturing excellence, German CNC production equipment, and distribution to 80+ countries, Elephant Fluid Power provides the fair pricing, fine quality, fast delivery, and world-class service that equipment operators and rebuilders worldwide depend on.

1. What Is the Rexroth A2F / A2FM Bent Axis Hydraulic Motor?

The Rexroth A2F and A2FM are fixed displacement axial piston hydraulic motors of bent-axis design, engineered to convert hydraulic fluid pressure and flow into reliable, high-efficiency rotary mechanical power. Unlike the swashplate-type axial piston units found in the A10VSO and A11VO pump series, the A2FM employs a fundamentally different mechanical architecture: the cylinder barrel is mounted at a fixed angle (typically 25 degrees) to the drive shaft axis, with tapered pistons arranged inside the barrel whose spherical ends engage directly with a spherical socket plate on the drive shaft. As pressurized hydraulic fluid enters the motor, it pushes the pistons outward from the barrel bores, and because the pistons are constrained by the angled spherical socket plate, this linear force is converted into rotational torque on the drive shaft.

This bent-axis configuration delivers several intrinsic performance advantages that have made the A2FM the workhorse motor for countless hydraulic drive applications across construction, mining, marine, agricultural, and industrial sectors. The direct piston-to-shaft connection through the spherical socket eliminates the intermediate shoe-and-swashplate mechanism found in swashplate designs, reducing friction losses and improving mechanical efficiency. The spherical valve plate distribution system provides automatic centering of the rotating group, ensuring consistent port timing and minimal internal leakage throughout the motor’s service life. The one-piece tapered pistons with integrated piston rings deliver superior sealing performance compared to conventional designs, maintaining high volumetric efficiency even after thousands of operating hours in contaminated environments.

The A2FM series is available in an exceptionally broad range of 22 displacement sizes — from the compact A2FM 5 (4.93 cm³) weighing only 2.5 kg to the massive A2FM 1000 (1000 cm³) delivering 5,570 N·m of torque — enabling precise matching to virtually any hydraulic drive application requirement.

1.1 A2F vs. A2FM: Understanding the Designation

While the terms A2F and A2FM are often used interchangeably in industry conversation, there is a meaningful technical distinction:

For practical procurement purposes, most buyers searching for “A2F motor” are seeking the A2FM motor variant. Elephant Fluid Power supplies all three variants (A2F pump/motor, A2FM motor, A2FE plug-in motor) with 100% interchangeability across the full size range.

1.2 The Bent-Axis Advantage: Why Engineers Choose A2FM Over Swashplate Motors

When selecting a hydraulic motor for a fixed-displacement drive application, engineers must choose between bent-axis (A2FM-type) and swashplate (A10VSO/11VO-type motor) architectures. The A2FM’s bent-axis design offers six compelling advantages for motor applications:

First — Superior Mechanical Efficiency: The bent-axis design’s direct piston-to-shaft connection through the spherical socket eliminates the shoe-to-swashplate sliding interface found in swashplate motors. This single design difference reduces frictional losses by 3-5 percentage points, enabling the A2FM to achieve mechanical efficiencies of 94-96% compared to 90-93% for equivalent swashplate motors. Over the lifetime of a motor operating 2,000 hours per year, this efficiency advantage translates to significant energy savings and reduced heat generation.

Second — Exceptional Starting Torque: The A2FM delivers starting torque exceeding 95% of theoretical torque — meaning the motor can develop nearly its full rated torque from a standstill. This is critical for applications like concrete mixer truck agitators (which must start under full load when the drum is full of concrete) and winch drives (which must hold and start with suspended loads). Swashplate motors typically achieve 85-90% starting torque, which can result in stalled starts under heavy load conditions.

Third — Higher Pressure Capability: The A2FM’s bent-axis design handles 400 bar nominal pressure and 450 bar peak pressure (for sizes 10-200), exceeding the 350/400 bar ratings of most swashplate motors. This higher pressure capability enables greater torque output from a given displacement or allows smaller, lighter motors to achieve the same torque as larger swashplate alternatives.

Fourth — Better Contamination Tolerance: The spherical valve plate design with automatic centering capability maintains proper port timing even when hydraulic fluid cleanliness is less than ideal. The one-piece pistons with piston rings resist wear from particulate contamination better than conventional piston-and-shoe assemblies. For equipment operating in dusty construction sites, muddy mining environments, or marine salt-air conditions, this contamination tolerance extends service life and reduces maintenance frequency.

Fifth — Radial Load Capability: The A2FM’s robust rolling bearing configuration enables the drive shaft to accept substantial radial loads — allowing the motor to drive pulleys, sprockets, and drums directly without requiring external support bearings. This radial load capacity simplifies driveline design and reduces component count in applications like conveyor drives, mixer drum drives, and fan drives.

Sixth — Compact Power Density: The bent-axis design achieves a favorable power-to-weight ratio, delivering high torque from a compact package. The A2FM 80, for example, produces 281 N·m of torque at 400 bar from a motor weighing only 23 kg — a power density that rivals or exceeds most competing motor technologies.

2. Complete A2FM Technical Specifications: All 22 Displacement Sizes

The A2FM series spans an extraordinarily wide performance envelope, from ultra-compact auxiliary drives to massive heavy-duty powertrains. The following tables organize the 22 available sizes into three practical groups for easier reference.

2.1 Compact Motors: A2FM 5 — A2FM 32 (Auxiliary and Light-Duty Drives)

These compact motors serve auxiliary drives, fan drives, small winches, and pilot/control functions where space and weight are at a premium.

2.2 Medium Motors: A2FM 45 — A2FM 125 (Primary Drive Applications)

This is the most popular size range for primary hydraulic drives, covering the majority of concrete mixer truck agitators, winch drives, travel drives, and swing drives in construction and mining equipment.

2.3 Heavy-Duty Motors: A2FM 160 — A2FM 1000 (Maximum Torque Applications)

These large-displacement motors deliver the maximum torque for the most demanding heavy-duty applications.

2.4 Pressure Ratings by Size Group

3. Application Guide: Where A2FM Motors Deliver Reliable Rotary Power

The A2FM’s unique combination of high efficiency, high starting torque, pressure capability, and contamination tolerance makes it the preferred motor choice across a remarkably diverse range of hydraulic drive applications.

3.1 Concrete Mixer Truck Agitator Drives

The A2FM motor is the dominant agitator drive for concrete mixer trucks worldwide. When a mixer truck is transporting concrete, the drum must rotate continuously at 1-15 RPM to prevent the concrete from setting. The A2FM motor — typically sizes A2FM 55, 63, 80, or 107 — provides the smooth, reliable low-speed rotation required for this critical function.

Why the A2FM excels as a mixer agitator motor: The over 95% starting torque ensures the drum starts reliably even when fully loaded with wet concrete. The contamination tolerance handles the harsh environment of construction sites where hydraulic fluid cleanliness is difficult to maintain. The compact size allows integration into the limited space available on mixer truck chassis. The bidirectional capability enables both mixing and discharge rotation directions.

Elephant Fluid Power stocks A2FM motors and all spare parts for concrete mixer agitator applications, serving mixer truck manufacturers and fleet operators worldwide. Common replacement parts include rotating groups, seal kits, and drive shafts.

3.2 Winch and Hoist Drives

The A2FM is widely used in hydraulic winches for cranes, marine vessels, mining equipment, and offshore platforms. The motor’s high starting torque provides reliable load lifting from a standstill, while the smooth low-speed operation enables precise load positioning.

3.3 Travel Drives for Excavators and Crawler Equipment

The A2FM powers track drives on crawler excavators, dozers, and other tracked equipment. When paired with a counterbalance valve (BVD/BVE), the A2FM provides controlled travel speed on slopes and prevents overspeeding during downhill operation.

3.4 Swing (Slew) Drives

The A2FM motor drives the upper structure rotation (swing) on hydraulic excavators and cranes. The motor’s smooth starting and precise speed control enable accurate positioning of the boom and bucket.

3.5 Crane and Material Handling Drives

3.6 Marine and Offshore Applications

3.7 Mining and Heavy Industry

4. Complete Spare Parts Program: 100% Interchangeable with Original Rexroth A2FM

Elephant Fluid Power manufactures over 1,300 types of hydraulic motor spare parts with 100% dimensional and functional interchangeability with original Rexroth A2FM components. The bent-axis design’s rotating group has unique components that differ from swashplate-type motors, requiring specialized manufacturing expertise.

4.1 Core Spare Parts for A2FM Motors

4.2 Cost Comparison: OEM Rexroth vs. Elephant Fluid Power A2FM Parts

5. Why Elephant Fluid Power? Fair Pricing, Fine Quality, Fast Delivery, World-Class Service

5.1 Fair Pricing: 50-75% Cost Savings

Elephant Fluid Power leverages manufacturing efficiencies in China’s advanced industrial corridor to deliver OEM-equivalent A2FM motors and parts at 50-75% lower cost. For a concrete mixer fleet operator with 20 mixer trucks (each requiring A2FM 80 agitator motors), switching to Elephant Fluid Power for annual maintenance yields $15,000-25,000 in parts cost savings per year.

5.2 Fine Quality: German CNC, Premium Materials, Zero-Defect Standards

The manufacturing facility features German CNC machining centers, CMM inspection, hydraulic test benches to 600 bar, and a material laboratory. Every A2FM motor and part undergoes documented quality control with 1.5× pressure testing before shipment.

5.3 Fast Delivery

5.4 Service That Serves the World

Elephant Fluid Power provides motor selection assistance, troubleshooting support, model identification from damaged nameplates, 12-month warranty, and custom engineering. Customer testimonials highlight responsiveness, technical competence, and genuine commitment to customer success:

“Very satisfied, good quality, fast delivery, saving a lot of costs for my motor.” — Martin, Europe

“Wow, it’s perfect. They sent the right accessories to me, and the installation is completely suitable.” — Filippo, Italy

6. How to Order: A2FM Motor and Parts Procurement Guide

6.1 Decoding the Rexroth A2FM Model Number

Common A2FM model numbers:

• A2FM63/61W-VAB020 — Standard concrete mixer agitator motor

• A2FM80/61W-VBB020 — Large mixer truck / small winch motor

• A2FM90/61W-VAB010 — Winch / travel drive motor

• A2FM107/61W-VSD510 — Crane hoist / medium winch motor

• A2FM125/61W-VAB010 — Heavy crane / mining motor

• A2FM160/61W-VZB010 — Large winch / industrial drive motor

6.2 Ordering Process

Send motor model number or part description to elephant@sjzhjsm.com or WhatsApp +86-180-3112-1586. Engineering confirmation and quotation within 24 hours. Payment via T/T, L/C, Western Union, or PayPal. Shipping via DHL/FedEx/UPS express or sea freight.

7. Frequently Asked Questions: A2FM Bent Axis Motors and Parts

Q1: What is the difference between a bent-axis motor and a swashplate motor?

A bent-axis motor (A2FM) has the cylinder barrel mounted at a fixed angle to the drive shaft, with pistons engaging directly with a spherical socket on the shaft. A swashplate motor has the cylinder barrel parallel to the shaft, with pistons pushing against an angled swashplate. The bent-axis design delivers higher mechanical efficiency (94-96% vs 90-93%), better starting torque (>95% vs 85-90%), higher pressure capability (400/450 bar vs 350/400 bar), and better contamination tolerance. For fixed-displacement drive applications, the A2FM bent-axis design is generally the superior choice.

Q2: What is the best replacement for a Rexroth A2FM motor?

Elephant Fluid Power manufactures complete A2F and A2FM motors in all 22 sizes (5-1000 cm³) with 100% dimensional interchangeability and identical performance characteristics to original Rexroth motors. All motors are assembled using German CNC-machined components, premium raw materials, and undergo 1.5× pressure testing before shipment. Buyers receive OEM-equivalent performance at 50-75% lower cost with delivery times of 2-4 weeks compared to 6-12 weeks for original Rexroth motors.

Q3: Which A2FM size do I need for my concrete mixer truck agitator?

• 3-6 m³ mixer trucks: A2FM 45, 55, or 63

• 7-10 m³ mixer trucks: A2FM 63, 80, or 90

• 12-16 m³ mixer trucks: A2FM 90, 107, or 125

If replacing an existing motor, order the same size as the original. The operating pressure for mixer agitators is typically 150-350 bar, well within the A2FM’s 400 bar rating. Elephant Fluid Power’s technical team can help identify the correct replacement from the mixer truck model or drum capacity.

Q4: How much can I save by buying A2FM parts from Elephant Fluid Power?

Complete A2FM motors cost 65-70% less than original Rexroth — an A2FM 80 is approximately $350-650 from Elephant Fluid Power versus $1,000-2,000 from Rexroth. An A2FM 107 costs $500-900 versus $1,500-2,800 OEM. Spare parts offer 65-75% savings — a rotating group costs $180-300 versus $600-1,000 OEM. For a mixer fleet with 20 trucks, annual maintenance savings typically exceed $15,000-25,000.

Q5: Does Elephant Fluid Power supply complete A2FM motors or only parts?

Both. Elephant Fluid Power supplies: complete A2F and A2FM motors (all 22 sizes), complete rotating groups (pre-assembled and pressure-tested), individual spare parts (cylinder blocks, pistons, spherical valve plates, drive shafts, seal kits), counterbalance valves (BVD/BVE), and motor repair/rebuild kits. All complete motors are fully assembled, pressure-tested, and ready for installation.

Q6: What is the warranty on Elephant Fluid Power A2FM motors and parts?

Elephant Fluid Power provides a 12-month warranty from the date of shipment against defects in materials and workmanship. The warranty covers free replacement of defective components upon return of the failed part for failure analysis. Motors and parts must be operated within published specifications for warranty coverage.

Q7: Can Elephant Fluid Power supply parts for other hydraulic motor brands?

Yes. Beyond the A2F/A2FM series, Elephant Fluid Power manufactures compatible spare parts for Rexroth (A6VM, A10VSO motor, A10VO motor, A4VG motor), Eaton/Vickers, Parker (F11/F12, TE/TF), Kawasaki (M3B, M3X), Sauer/Danfoss (90M, 51V), Linde (BMR, BMV), and other major brands. Over 1,300 types of spare parts in total.

Q8: What spare parts are most commonly replaced on A2FM motors?

The most frequently replaced A2FM components are: seal kits (recommended at every major service interval — shaft seals degrade over time due to heat and contamination), rotating groups (when wear exceeds tolerance after thousands of hours), spherical valve plates (when scoring or wear affects port timing), piston sets (when piston rings no longer seal effectively), and drive shafts (when spline wear or bearing damage occurs).

Q9: What is a counterbalance valve (BVD/BVE) and do I need one?

A counterbalance valve is an optional safety device mounted on the A2FM motor for travel drive and winch applications. It prevents the motor from overspeeding when traveling downhill or lowering a load by automatically throttling the return flow if inlet pressure drops below approximately 20 bar. The BVD is available for A2FM sizes 28-180; the BVE for sizes 107-180. We strongly recommend ordering the counterbalance valve and motor as a matched set for travel and winch applications.

Q10: How do I contact Elephant Fluid Power for an A2FM quotation?

Contact Information:

• Website: www.hydpumpparts.com

• Email: elephant@sjzhjsm.com

• Phone/WhatsApp: +86-180-3112-1586

• Office Phone: +86-311-6812-3061

• Address: No.398 Youyi Street, Xinhua District, Shijiazhuang City, Hebei, China

• Business Hours: 8:30-18:00 Beijing Time (UTC+8)

For fastest response, include your motor model number (or equipment make/model), required parts description, quantity, and destination country. Quotations within 24 hours.

8. Technical Specifications Summary: A2FM Series at a Glance

9. Conclusion: The Proven Choice for Reliable Hydraulic Rotary Power

The Rexroth A2F / A2FM bent axis fixed displacement hydraulic motor has earned its position as one of the most trusted and widely deployed hydraulic motors in the world through decades of proven performance in the most demanding applications. From the concrete mixer trucks that build our cities to the mining equipment that extracts essential resources, from the crane winches that lift heavy loads to the marine systems that navigate our oceans, the A2FM delivers the high efficiency, high starting torque, and reliable performance that equipment operators depend on.

When these motors require replacement or repair, Elephant Fluid Power Co., Ltd. stands ready as your trusted global partner — delivering complete A2F and A2FM motors in all 22 sizes and over 1,300 types of 100% interchangeable spare parts with OEM-equivalent performance at 50-75% lower cost. With nearly 20 years of manufacturing excellence, German CNC production equipment, distribution to 80+ countries, and an unwavering commitment to fair pricing, fine quality, fast delivery, and world-class service, Elephant Fluid Power has earned its position as a leader in the hydraulic motor aftermarket.

Ready to request your A2FM quotation? Visit www.hydpumpparts.com or contact elephant@sjzhjsm.com with your motor model number or part requirements. Our technical team will provide specification confirmation, competitive pricing, and delivery options within 24 hours.

About Elephant Fluid Power Co., Ltd.

Established in Shijiazhuang, Hebei Province, China, Elephant Fluid Power Co., Ltd. is a professional manufacturer and global supplier of hydraulic piston pumps, hydraulic motors, pump and motor spare parts, and hydraulic components. With nearly 20 years of experience, the company produces Rexroth-compatible A2F, A2FM, A2FE, A6VM, A10VSO, A10VO, A11VO, A20VO, A4VG, A4VSO, A2FO, and A7VO series pumps and motors, along with over 1,300 types of 100% interchangeable spare parts. Elephant Fluid Power serves customers in 80+ countries across concrete mixer trucks, construction machinery, mining equipment, cranes, winches, marine systems, and industrial drives. Our mission: fair pricing, fine quality, fast delivery, and service that serves people worldwide.

Contact Information:

• Website: www.hydpumpparts.com

• Email: elephant@sjzhjsm.com

• Phone/WhatsApp: +86-180-3112-1586

• Office: +86-311-6812-3061

• Address: No.398 Youyi Street, Xinhua District, Shijiazhuang City, Hebei, China