Rexroth Hagglunds CAB series Radial piston hydraulic motor

The Hägglunds CAB (also written CAb) is a low-speed, high-torque radial piston hydraulic motor manufactured by Bosch Rexroth under its Hägglunds brand, a product line historically associated with heavy industrial direct-drive technology (mining, marine, pulp & paper, steel, and material handling). The CAB was introduced as a smaller, lighter evolution of Rexroth's earlier CA/CB motor platforms — delivering the same output as its predecessors while being far smaller and lighter, giving it unmatched power density.

How a Radial Piston Motor Actually Works

Unlike axial piston or gear motors, a radial piston design arranges its pistons like spokes around a central shaft rather than in a line parallel to it. Understanding this geometry is the key to understanding why the CAB behaves the way it does under load.

The Core Mechanism

The Hägglunds CAB is a radial-piston motor with a rotating cylinder block/hollow shaft and a stationary housing, with the cylinder block mounted in fixed roller bearings inside the housing. An even number of pistons sit radially in bores inside the cylinder block, and a distributor routes incoming and outgoing oil to and from each working piston. Every piston pushes against its own cam roller.

When hydraulic pressure acts on the pistons, the cam rollers are forced against the slope of a cam ring that's rigidly fixed to the housing, generating torque. The cam rollers pass that reaction force back into the pistons, which are guided inside the cylinder block, and rotation follows — with system pressure directly proportional to the required torque. In plain terms: the harder the load resists turning, the higher the pressure climbs to overcome it, right up to the relief setting. No gear reduction, no clutch, no flexible coupling — pressure goes in, torque comes out.

Why the Symmetry Matters

Because the pistons are arranged symmetrically around the shaft, radial forces oppose and cancel each other out, and there are no centrifugal forces generated by the rotation. This is also why radial piston motors like the CAB run with essentially no flow pulsation — the design gives no vibration and 100% constant displacement throughout the rotation cycle. For applications like paper machine drives or ship's winches, where torque ripple translates directly into product defects or rope wear, that smoothness is not a nice-to-have; it's the reason the motor gets specified in the first place.

Ports and Oil Flow

Main oil lines connect to ports A and C on the connection block, while drain lines run to ports D1, D2, and D3 on the motor housing. The motor connects to the driven machine's shaft through its own hollow shaft, which is what allows the CAB to be flange-mounted or torque-arm mounted directly onto a drum, wheel, or agitator shaft without an intermediate gearbox.

Typical Applications

Because the CAB trades some absolute torque ceiling (compared to CB/CBm) for compactness, it tends to show up wherever space and weight are as important as raw output:

Winches and hoists on cranes, offshore platforms, and marine deck equipment, where a compact direct drive frees up deck or frame space

Conveyor and belt drives in bulk material handling, where low-speed, high-torque output avoids the need for a right-angle gearbox

Mixers and agitators in process industries needing smooth, pulsation-free rotation at variable speed

Rotary tables and turntables in manufacturing and material-handling cells

Auxiliary drives in mining and steel-mill equipment where a lighter motor simplifies retrofit projects

Installation and Maintenance Notes

A few details matter disproportionately in the field:

Spline lubrication is not optional. Splines must be lubricated and filled with hydraulic oil at assembly, or filled with transmission oil from a connected gearbox, and kept within specified installation tolerances — skipping this step is one of the more common causes of premature spline wear on direct-drive installations.

Drain line routing matters for case pressure. With three separate drain ports (D1, D2, D3) on the housing, correct drain routing keeps case pressure within limits and protects shaft seals — this is worth double-checking against the installation manual rather than assuming a "standard" hookup.

External load limits are frame-specific. Permissible radial and axial dynamic and static loads vary by frame size and mounting style (flange vs. torque-arm), so external load charts should be checked against the actual mounting configuration rather than a generic figure.

Viscosity affects rated performance. Load and speed charts in Rexroth's documentation are typically referenced to a specific oil viscosity (commonly around 40 cSt), so field oil condition and temperature should be tracked to keep the motor operating within its intended envelope.

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

Specifications

Selection Table

Q1: What does "CAB" stand for in Hägglunds CAB?

A1: It's a Bosch Rexroth model designation within the Hägglunds radial piston motor family (also seen written as "CAb"), distinguishing it from the related CA, CB, and CBm series by frame design and power density.

Q2: What industries typically use the Hägglunds CAB motor?

A2: Marine and offshore, mining, pulp and paper, steel, and general heavy material handling are the classic Hägglunds strongholds, anywhere a compact, low-speed, high-torque direct drive beats a mechanical transmission on reliability or footprint.

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

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

Q4:How to purchase a CAB hydraulic motor?

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