Power take-off

Most commonly, it is a splined drive shaft installed on a tractor or truck allowing implements with mating fittings to be powered directly by the engine.

These applications typically use a drive shaft and bolted joint to transmit power to a secondary implement or accessory.

For moving vehicles such as a traction engine or early tractor towing a farm implement, the implement could receive rotary power by taking it from one of its own wheels (whose turning was imparted by the towing) and distributing it via roller chains (to a sickle bar's crank, for example), but such a transmission ceases if the vehicle stops traveling, and the workload's resistance tends to make the wheel skid rather than turn, even if cleated.

[3] Edward A. Johnston, an IHC engineer, had been impressed by a homemade PTO that he saw in France about a decade before, improvised by a French farmer and mechanic surnamed Gougis.

Inside the transmission, the exact point along the gear train where the power is taken off determines whether the PTO can be run independently of vehicle travel (ground speed).

It also allows operations where the tractor remains parked, such as silo-filling or unloading a manure spreader to a pile or lagoon rather than across a field.

Live PTOs eventually became a widespread norm for new equipment; in modern tractors, LPTO is often controlled by push-button or selector switch.

Incidents can occur when loose clothing is pulled into the shaft, often resulting in bone fractures, loss of limbs, other permanent disabilities, or death to its wearer.

[5] Some implements employ light free-spinning protective plastic guards to enshroud the PTO shaft;[6][7] these are mandatory in some countries.

[10] Two newer types, supporting higher power applications, operate at 1000 rpm and differ in shaft size.

It operates at a higher rotational speed of 1300 rpm in order to allow for power transfer at reduced levels of torque.

Newer tractors may come equipped with 540/540E and/or 1000/1000E options that allow the tractor to power certain low-power-demand implements like hay rakes or tedders using lower engine speeds to maintain the revolutions per minute needed, using less fuel and placing less stress on the engine – thereby improving efficiency and reducing costs.

The first industry standard for PTO design was adopted by ASAE (the American Society of Agricultural Engineers) in April 1927.

Due to the sandwich mounting style, the gearbox will be moved away from the engine, requiring the driveline to accommodate the installation.