Power take-off
A power take-off (also known as PTO or after the abbreviation of power take-off as a PTO called) is mainly in tractors and trucks and some commercial vehicles a mostly switchable mechanical power source to a secondary output of the transmission ready. The mechanical drive energy can be used directly via a cardan shaft or z. B. drive attached cutter bars , belt drives or hydraulic pumps .
In modern tractors, the PTO is located in the middle between the three-point linkage at the rear , and in models with front attachment options, it is also located at the front.
Direct drive
If the devices are to be driven while the vehicle is stationary, the speed of the engine and thus the PTO shaft speed can simply be regulated with the accelerator pedal or the hand throttle ( cable winch , irrigation pumps ). This power take-off is often used on municipal vehicles that are used for street cleaning, salt spreading and snow clearing.
On tractors , the power take-off is called the power take-off shaft and is used to drive water pumps , mowers , loading wagons and many other agricultural attachments . The PTO shaft is also used in forestry , for example in modern log splitters .
To the profiled shaft stub which projects from the gear, a is a spline or - involute toothing provided propeller shaft attached. This shaft was previously secured by a spring-loaded slide pin that engaged in a circular groove on the stub shaft of the PTO shaft. With the introduction of DIN EN 12965 in 2005, sliding pin locks on the tractor side are prohibited and should be replaced with rotationally symmetrical locks in the event of repair or replacement. The cardan shaft can be removed without tools for all common types of lock . The common profile shapes of the PTO shaft are the 1-3 / 8-inch and 1-3 / 4-inch splined shaft profile with six "teeth", the 1-3 / 8-inch splined shaft profile with 21 teeth and the 1¾-inch Splined shaft profile with 20 teeth (involute profile).
A direct power take-off is mostly used in fire engines that have a built-in fire pump .
Indirect drive
A power take-off is used in trucks , commercial vehicles and tractors as a secondary drive . In most cases this is a hydraulic pump that drives smaller oil motors via hose lines or supplies lifting cylinders with energy. It is also common to attach angular and belt drives to tractors.
If an indirect power take-off is standard for trucks and heavy commercial vehicles, this was only possible as an option for light all-wheel drive commercial vehicles until 2016 for the Land Rover Defender and Toyota Land Cruiser .
PTO types
- Engine PTO
- is generally connected directly to the engine via a separate clutch or double clutch and thus runs at a standard speed (see below) only depending on the engine speed. It enables the tractor to be stopped or started while the secondary unit is still running. Certain harvesting machines such as balers, self-tying machines or pulled combine harvesters can otherwise overload, which often makes it necessary to "clear" the blockage by hand.
- Transmission PTO
- is connected to the engine via the drive clutch and a gearbox; the nominal speeds are standardized. The two standard speeds 540 / min and 1000 / min are geared down so that they can be achieved in the range of the nominal engine speed (maximum output). For some time there have also been the speeds called 540E and 1000E (Economy), at which the nominal speed of the PTO shaft is reached at a reduced engine speed, usually close to the highest engine torque at around 1400 to 1600 rpm. This makes it possible to operate devices with low power consumption in a fuel-efficient manner.
- Road PTO
- their torque decreases after the drive gear. Your speed and often also the direction of rotation depends on the selected gear and thus the speed. Just like the transmission PTO, it stops when the drive clutch is disconnected. This PTO shaft is used, for example, on drive axle trailers. This improves the traction of the train in difficult terrain and prevents it from getting stuck.
Annotation:
- Usually a tractor has a transmission or an engine PTO shaft. The road PTO is an additional option, the importance of which has decreased in agriculture as the tractor size increases.
- In Austria there is still the 432 rpm speed of the rear PTO, which is used when a mower is attached to the front of the tractor, which can only be operated at the rated speed, and a loader wagon is attached to the rear. The loader wagon is driven at a gentle speed at 432 rpm in order to increase its service life. In addition, the sward is protected by the slower drive: the loading unit of the loading wagon scratches the ground more slowly and less frequently (in relation to the distance traveled).
literature
- Kurt-Jürgen Berger, Michael Braunheim, Eckhard Brennecke: Technology automotive engineering. 1st edition. Verlag Gehlen, Bad Homburg vor der Höhe 2000, ISBN 3-441-92250-6 .
- Horst Eichhorn (editor): Landtechnik. 7th edition. Ulmer, Stuttgart 1952, 1999, ISBN 3-8001-1086-5 , p. 94 f.
See also
Web links
Individual evidence
- ↑ Archived copy ( memento of the original from July 26, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Information about power take-offs
