Hydrostatic motor drive gives users the creeps

Hydrostatic Creep Drive makes sense on vehicles that move on a regular basis and must have controlled ground speed.

Faster is better, or so the saying goes. But in some applications, slow and steady is what's really needed. Cotta Transmission Co., Beloit, Wis., has answered that need with their new Hydrostatic Motor Creep Drive. The new transmission is designed to be installed between a vehicle's main transmission and drive, allowing it to creep along at the slow speeds required in a wide variety of work applications.

Once on the job site, the truck operator simply shifts the main transmission into neutral, the creep mode is selected, and a hydrostatic motor rotates the driveline through a reduction gear set in the auxiliary gearbox. This allows precise vehicle speed control down to inches per minute. In addition to speed control, the main transmission is protected, as it is removed from the wear and tear of start-stop operations. When shifted back to the road mode, the gears disengage and do not rotate, so horsepower loss and heat generated from gears churning in the oil — as well as back-driving the hydraulic motor — is eliminated.

Applications include cement trucks (to allow chute discharge control remotely from the back, rather than the front of a ready mix truck), and posthole digging for highway safety railings, where back-driving through a vehicle's main transmission can cause failures. The drive may also be suitable for highway paint stripers, airplane de-icers, street sweepers, refuse trucks, railroad tie grapple trucks, and even agricultural feed mixers.

The TR2218 current single reduction Creep Drive model has a capacity of 12,500 lb-ft through the shaft, and maximum hydraulic motor torque is 900 lbft. The shift mechanism is an air cylinder-with dog-type clutch. Input and output shaft spline size is 23/4 10.

For more information, contact Cotta Transmission at (608) 368-5634 or visit www.cotta.com.