Power take-offs (PTO) are extensions of a vehicle's drive train that can be engaged to power auxiliary equipment such as plows, augers, winches, and many other material handling, construction, and agricultural implements. PTOs require special handling and safeguards because of the danger of becoming entangled in the moving shaft. PTOs are also commonly used with trucks to power auxiliary units, such as dumping or tipping mechanisms, compactors, snowplows, cranes, and lifts. A truck power auxiliary unit may also include a cement mixer, fire equipment on a fire truck, sewer cleaning trucks, and sweeper vehicles. 

Specifications

Specifications for PTOs include:

• number of mounting bolts
• torque rating
• weight
• housing material
• direction of rotation

Typically, the number of mounting bolts is four, six, or eight. Torque rating refers to the highest intermittent torque that PTOs are designed to withstand. Weight is measured in pounds (lbs) or kilograms (kg). Choices for housing material include aluminum, cast iron, steel, and stainless steel. The direction of rotation is described as opposite engine rotation, same as engine rotation, or bi-directional. PTOs that carry other specifications are also available.

PTOs are operated at very high speeds and pose a danger to operators. They must have well-maintained and properly fitted guards or shields when they are being operated to protect people from getting entangled in the shaft. PTO shielding consists of a guard that covers both the top and the sides of the PTO, and encloses the entire drive shaft of the PTO from the tractor or truck to the first bearing on the auxiliary equipment. A PTO shaft shield must be properly fitted to cover the entire exposed length of the shaft and may also have to accommodate for the vertical and lateral movements of the PTO. 

Applications

Split shaft PTOs are designed to allow one engine to drive both the vehicle and the auxiliary equipment. Split shaft PTOs can provide engine power to either the vehicle’s drive axle or to the equipment by switching the mode of operation with the main clutch in the gearbox. This type of PTO is designed to run either the vehicle axle or the auxiliary equipment, not both at the same time. Split shaft PTOs are used to power oil drilling rigs, concrete pumpers, compressors, pumps, and lifts.

Related Information

CR4 Community—Flywheel-Operated Electric Generator

Image credit:

bdk / CC BY-SA 3.0