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Hagglunds radial-piston hydraulic motor
A Hagglunds radial-piston hydraulic motor (visible on left side or winch near bottom) provides high torque in a compact size, making it well suited to winch drives used in marine environments.

Radial-Piston Motor is a Natural for Marine Drives

The Hägglunds CA hydraulic motor was developed for a specific purpose: to provide high torque from a small package. Offered by Bosch Rexroth, the Hägglunds CA motor can mount directly onto the driven shaft, an arrangement that makes it much smaller and lighter than the next-best alternative—an electric motor driving a shaft-mounted gear reducer though a belt drive.

Not only is the CA motor lighter and far smaller than electromechanical alternatives, load torque exceeding the motor’s torque output simply causes it to stall, rather than overheat. Unlike electric motors, it needs no cooling fan (which can pull in dirt and water), and it doesn’t have belts that need to be periodically replaced.

A Hägglunds CA motor delivers continuous high-torque power continuously, and the motor’s low inertia allows effective torque limitation from zero to maximum speed. It’s especially well-suited to winch drives due to its fast-acting pressure control that minimizes transients of strain. It also achieves four-quadrant operation—driving and braking in forward and reverse.

A variety of modular valves provide versatile drive options. Mounting the motor directly onto a winch drum and outfitting it with brakes and the appropriate valves creates a free-wheeling drive that enhances safety by enabling immediate emergency release. This feature can be capitalized on in other situations, such as shooting out the net on a fishing vessel. For example, when paying in fishing net, an operator can first select the high-speed range, then switch to low-speed for maximum line pull when lifting. For a winch or crane in cargo operations, overload protection if provided if a hook or load should jam. In this situation, the Hägglunds CA can stop instantaneously due to its low moment of inertia. Furthermore, installing a DNV-approved safety brake on the drum can minimize the risk of dropping a load if a drive line fails.

The drive system can provide infinite speed variations, moving slowly or accelerating rapidly, and allows precise positioning. This is useful not only for cranes and winches, but in modern maneuvering applications, such as azimuth propulsion drives on cruise ships. Regardless of the speed, the motor can transmit full torque continuously.

For more information, visit Bosch Rexroth's website.

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