Rexroth A2FM200 fixed displacement hydraulic motor

The A2FM200 is a fixed-displacement, bent-axis axial piston motor built by Bosch Rexroth, part of the broader A2FM series that spans displacements from 5 cm³ to 1000 cm³ per revolution. The "200" designates its geometric displacement: 200 cm³ per revolution.

Unlike variable displacement motors (the A6VM or A2FE series, for example), the A2FM200 has no swash or swivel angle adjustment mechanism — its displacement is fixed by design. That simplicity is the whole point: fewer moving parts controlling geometry means higher reliability, a smaller footprint, and lower cost, at the expense of the flexibility a variable unit offers.

How the A2FM200 Works

The A2FM200 uses a bent-axis rotary group, which is mechanically different from the swash-plate design found in many other axial piston motors. Here's the short version of the physics:

1. Pressurized fluid enters the motor and acts on a set of tapered pistons arranged around a cylinder block.

2. Because the cylinder block's axis is set at an angle relative to the output shaft (the "bent axis"), the pressure force on each piston resolves into a torque-producing component.

3. As the pressure differential pushes the pistons, the cylinder block — and with it the output shaft — rotates.

4. Output torque scales with the pressure differential between the high- and low-pressure ports; output speed scales with input flow rate.

Why Bent-Axis Instead of Swash-Plate?

The bent-axis geometry gives the A2FM200 a few practical advantages that matter in demanding applications:

High starting torque — typically above 95% of theoretical torque, which matters enormously for winches, drill drives, and anything that needs to break static friction under load.

Smooth low-speed operation with minimal torque ripple, because the piston forces are well-balanced through the rotation cycle.

Strong power-to-weight ratio, since the compact bent-axis layout packs more displacement into less housing volume than an equivalent swash-plate design.

High mechanical and volumetric efficiency, often in the 92–96% range at the motor's best operating point.

The trade-off is a slightly more complex internal geometry and a marginally larger installed envelope than some cartridge-style motors — an acceptable compromise for the performance it buys.

Typical Applications

The A2FM200's displacement class puts it squarely in the range for medium-to-heavy mobile and industrial equipment that needs real torque without needing extreme speed.

Construction and Earthmoving Equipment

Slew drives, travel drives, and winch drives on excavators and cranes lean on fixed motors like the A2FM200 because the load profile — high torque at low-to-moderate speed — plays directly to the bent-axis design's strengths.

Drilling Rigs

Rotary and auger drives on drilling rigs need consistent torque delivery under variable resistance (different soil and rock conditions). A fixed displacement motor gives predictable, repeatable output that operators can rely on without compensating for a variable unit's control lag.

Conveyors and Crushers

Mineral processing and aggregate handling equipment runs motors like the A2FM200 continuously, often in dusty, high-vibration environments. The motor's rugged bearing arrangement and sealed rotary group are built for exactly that duty cycle.

Railway Maintenance Machines

Tamping machines, rail grinders, and other maintenance vehicles use A2FM-class motors for track-side actuation and drive functions where reliability under intermittent, high-load starts is non-negotiable.

Installation and Circuit Considerations

A few things experienced hydraulics techs check every time they install or replace an A2FM200:

Fluid Compatibility and Viscosity

The A2FM200 runs on mineral oil as standard, with HFB and HFC fire-resistant fluids also approved for this size class (note: HFD fluids are only approved for the larger 250–1000 sizes with the long-life bearing option, and HFA fluids are not suitable at all). Optimal operating viscosity sits in the 16–36 mm²/s range, depending on circuit and tank temperature — straying outside this band accelerates wear on the piston-shoe interface and valve plate.

Case Drain Line

Bent-axis motors depend on an unrestricted case drain path to the tank. Any back-pressure in the case drain line directly stresses the shaft seal — this is one of the most common (and most avoidable) causes of premature seal failure in the field.

Open vs. Closed Circuit

The A2FM200 is rated for both open and closed hydrostatic circuits. In closed-circuit hydrostatic transmissions (common in travel drives paired with a variable pump), pay close attention to charge pressure requirements and flushing valve configuration, since the motor's case drain and shaft seal ratings assume the charge system is doing its job.

Mounting and Alignment

Like any axial piston unit, shaft misalignment with the driven component (gearbox, wheel hub, drum) shortens bearing life fast. Use a flexible coupling or verify spline engagement carefully, and torque the flange bolts to the specified value — under-torqued mounting bolts are a surprisingly common warranty claim.

For more information on the A2FM200 hydraulic motor, please visit https://www.baolilaihydraulic.com/product/.

Specifications

Selection Table

Q1: Can the A2FM200 run in a closed-loop hydrostatic transmission?

A1: Yes. The A2FM series, including the A2FM200, is designed for both open and closed-circuit hydrostatic drives. Closed-circuit applications need proper charge pressure and case drain management to protect the shaft seal.

Q2: How do I know if my A2FM200 needs to be rebuilt or replaced?

A2: Watch for a gradual drop in output torque or speed at the same input conditions (a sign of internal leakage/wear), unusual noise or vibration, or case drain flow that's climbing over time. Any of these warrants inspection before the motor fails outright.

Q3: What is the price and delivery time of the A2FM200 hydraulic motor?

A3: The specific price and delivery time will be provided based on the specific model you provide.

Q4: How to purchase an A2FM200 hydraulic motor?

A4: You can visit https://www.baolilaihydraulic.com/contact/ to contact us and purchase our products through various methods.