Bosch Rexroth AA2FLM Fixed Displacement hydraulic motor

Designed as a bent-axis fixed displacement motor, the AA2FLM series is engineered for open and closed-loop circuits where performance density matters. Whether you are designing a marine winch, a plastic injection molding machine, or a heavy-duty press, this motor delivers German engineering precision without overcomplicating the system.

What Makes the AA2FLM Different? Core Design Philosophy

The Bent-Axis Advantage

Most fixed displacement motors use axial piston designs with a swashplate. Rexroth’s AA2FLM uses a bent-axis principle, where the cylinder block is angled relative to the drive shaft. This results in:

Higher starting torque efficiency (typically >90%).

Smoother low-speed operation down to single-digit RPMs.

Superior tolerance to shaft loads—both radial and axial.

Applications with Examples

The AA2FLM is not a "general purpose" motor. It thrives where ordinary motors fail—under continuous high torque, high side load, or limited installation space.

Example 1: Marine Deck Cranes

A ship’s crane operates in a salt-spray environment with constant shock loads. Using an AA2FLM size 250, engineers achieve a hoist torque of over 3,000 Nm at 350 bar. The bent-axis design allows the motor to be mounted directly to a planetary gearbox input shaft, eliminating a flexible coupling—saving axial space and reducing maintenance points.

Example 2: Plastic Injection Molding Screw Drives

Here, low speed (20-100 rpm) and high torque are critical for melt uniformity. The AA2FLM’s fixed displacement ensures consistent plasticizing torque. Compared to variable motors, the fixed version prevents drift in screw speed, improving shot weight repeatability by ±1%.

Example 3: Agricultural Forage Harvesters

High radial loads from belt drives often destroy standard piston motors. The AA2FLM integrates reinforced tapered roller bearings as standard, handling side loads up to 5,000 N without derating.

Installation & Optimization

You don’t just bolt on an AA2FLM and hope for the best. Here’s how to extract maximum life and efficiency.

Casing Drain Line is Mandatory

Because the bent-axis design has internal leakage (typical 2-4% of flow), you must connect the case drain port to tank with no back pressure. Limit case pressure to ≤2 bar absolute. Exceed this, and you risk blowing the shaft seal.

Charge Pressure for Closed-Loop Systems

When used in a closed circuit (e.g., hydrostatic transmission), maintain a minimum charge pressure of:

15 bar for high-speed applications (>3,000 rpm)

10 bar for low-speed, high-torque scenarios

Filtration is Not Optional

Bosch Rexroth specifies a minimum fluid cleanliness of ISO 4406: 18/16/13 (equivalent to NAS 7-9). Use a return-line filter with β10 ≥ 200. Dirty oil turns the AA2FLM’s precision pistons into expensive grinding paste.

For more information on the AA2FLM hydraulic motor, please visit https://www.baolilaihydraulic.com/product/.

Specifications

Selection Table

Q1:What is the difference between AA2FLM and A2FM series?

A1:The “L” in AA2FLM denotes longer bearing bridges and reinforced shaft bearings. The A2FM is the standard industrial version; the AA2FLM is for applications with higher external radial or axial shaft loads.

Q2:Why does my AA2FLM run hot at low speed?

A2:Likely inadequate case flow for cooling. At low speeds (<500 rpm), the internal pumping action of the pistons is minimal. Add a separate case flush circuit or increase charge flow to ≥15 L/min for size 250.

Q3:What is the price and delivery time of the AA2FLM hydraulic motor?

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

Q4:How to purchase an AA2FLM hydraulic motor?

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