Bosch Rexroth A4FM28 Series Fixed Displacement Axial Piston Motor Parts & Rotary Group

Key Specifications

Overview

HYLINK supplies precision-engineered Bosch Rexroth A4FM series (A4FM28) swashplate-design axial piston fixed motor replacement parts and complete rotary group overhaul kits. Designed for high-pressure open and closed-circuit hydrostatic drives, our A4FM28 components deliver 100% full interchangeability with original Bosch Rexroth units. Built with high-tensile alloy materials and precise micro-honing techniques, every component undergoes strict quality testing to ensure maximum torque performance and long operating life under severe working conditions.

Product Overview

The Bosch Rexroth A4FM28 swashplate axial piston motor is engineered for high-pressure industrial and mobile hydraulic drives. Operating under extreme continuous pressures (up to 400 bar) and high-speed reversals, internal components—such as the cylinder block, pistons with slipper shoes, swashplate, valve plate, and ball guide—experience heavy friction and thermal fatigue over extended service hours. Wear on these critical rotating surfaces leads to pressure loss, internal fluid leakage, increased system temperature, and reduced output torque.

HYLINK manufactures high-precision complete replacement rotary groups and individual spare parts specifically for the A4FM28 motor frame. Produced from premium forged alloy steel and high-wear-resistant brass compositions, each part undergoes micron-level CNC machining and CMM dimensional inspection. This allows hydraulic service centers and fleet maintenance teams to rebuild worn motor rotary assemblies quickly without replacing the main housing, significantly lowering maintenance costs while restoring factory-level motor power output.

Available Components

Below is the standard component list for Bosch Rexroth A4FM28 hydraulic motors. Individual spare parts and complete overhaul repair kits are both available:

Quality Assurance & Manufacturing

Every HYLINK pump and replacement part undergoes strict quality control before shipment:

l Dimensional accuracy — checked with high-precision CMM (Coordinate Measuring Machines) to guarantee an exact fit with original pump housings.

l Material metallurgy — manufactured from premium forged steel and high-wear-resistant alloys to prevent premature fatigue.

l 100% performance test — every complete pump assembly is tested on our dynamic hydraulic test rig for pressure, flow rate and efficiency under full working load.

Packing, Shipping & Warranty

l Packaging — anti-rust protective film + heavy-duty foam cushioning + standard export fumigation-free wooden case (reinforced carton for small spare parts).

l Shipping — express courier (DHL / FedEx) for urgent repair orders; sea or air cargo for bulk orders.

l Warranty — 6 months quality assurance against manufacturing and material defects from the delivery date. In the event of a confirmed quality defect, HYLINK provides hassle-free replacement.

FAQ

Q: Are your SBS pump parts interchangeable with genuine Caterpillar parts?

A: Yes. All parts are produced to original specifications and dimensions and are 100% interchangeable — no modification is required during installation.

Q: What is the minimum order quantity?

A: 1 piece. We supply both individual components and complete rotary group / repair kits.

Q: How fast can you ship?

A: In-stock items are dispatched within 1–3 days; standard production orders take 5–8 days. Express and sea/air freight are both available.

Q: How do I confirm the correct part for my machine?

A: Send us your excavator model, pump model (SBS80 / SBS120 / SBS140) and the part name or photo — our technical team will confirm the correct item before you order.

Q: What warranty do you offer?

A: 6 months against manufacturing and material defects, with replacement support for confirmed quality issues.