Power take-off

A power take-off (also known as PTO or after the abbreviation of the English term power take -off as PTO ) provides a mostly switchable mechanical power source to a secondary output of the transmission especially in tractors and trucks and some commercial vehicles. The mechanical drive energy can be used directly via a propeller shaft or drive, for example, grown cutter bar, belt drive or hydraulic pumps.

In modern tractors, the PTO is located centrally between the three-point linkage at the rear, for models with front-mounted option also in addition to the front.

Direct drive

If the devices are to be driven at a stationary vehicle, is easy to fix to control with the accelerator pedal or hand throttle the speed of the motor and thus the PTO speed ( winch, Beregnungsspumpen ). Frequently used for this take-off in municipal vehicles, which are used for street cleaning, snow removal and salt spreading.

For tractors PTO PTO is called and is used to drive water pumps, mowers, wagons and many other agricultural implements. Also in forestry finds the PTO application, for example in modern wood-splitting machines.

At the profiled stub shaft that protrudes from the gear, one is provided with a spline or involute - tooth propeller shaft is plugged. Securing this shaft is secured by a spring- pressure sliding pin which engages a circumferential groove round on the stub shaft PTO. In order for the propeller shafts are removable without tools. The common profile of the PTO are the sechskeilige 1-3/8-Zoll-Keilwellenprofil, the 1-3/4-Zoll-Keilwellenprofil and the 21 -tooth involute profile.

A direct power take-off is usually used in fire-fighting vehicles, which have a built-in fire pump.

Indirect drive

Use is an auxiliary output for trucks, commercial vehicles and tractors also to the secondary drive. In most cases this is a hydraulic pump via hose lines smaller oil engines driving or lifting cylinders supplied with energy. On tractors also the cultivation of angle and belt transmission is common.

PTO types

• The PTO is usually via a separate clutch or dual clutch directly connected to the motor and thus runs at a standard speed (see below ) is only a function of the engine speed. It allows you to stop or start the tractor, while continuing to slave. In certain harvesters such as baler, self- tie or towed harvesters may otherwise be overloaded, which necessitates often a " händisches freeing " of constipation.
• The transmission is connected to the PTO clutch, and a transmission connected to the motor, the rated speeds are standardized. The two standard speeds 540 rpm and 1000 rpm are so stout that they be achieved in the field of motor rated speed ( maximum power). For some time, there is also the 540E and 1000E (Economy) referred to speeds at which the rated speed of the PTO at reduced engine speed, usually in the vicinity of the engine maximum torque is reached at about 1400 to 1600 rpm. This makes it possible to operate low-power devices save fuel.
• The ground speed PTO torque takes her off to the driving gear. So your speed and often the direction of rotation of the gear selected and thus depends on the speed. As well as the Getriebzapfwelle stops them when the clutch is disconnected. This PTO is used for example in driving axle trailers. Thus, the traction of the train can be improved in difficult terrain and a hard drive can be avoided.

Note:

• Usually, a tractor has a transmission or an engine PTO. The ground speed PTO is an additional option, whose importance has declined in agriculture with increasing tractor size.
• In Austria there is the 432/min-Drehzahl the rear PTO, which is used when the tractor forward a mower is attached, which can only be operated at rated speed, and a rear loading trailer is attached. With the 432/min the charging car is driven at a considerable speed in order to increase its life span. In addition, the turf is protected by the slower drive: The charging unit of the loading car scratched slower and less often (compared to route) on the ground.