As we all know, tractors are necessary for modernization of agriculture but not sufficient. It is the use of tractors to operate different types of implements that makes the tractors worth and profitable for farmers. Now, different types of implements require different mechanisms to operate. Some require only drawbar power, hydraulics, or PTO power to operate. But here in this article, win almost focusing on PTO tractor found today almost in all modern tractors.
Tractor PTO full form is Power Take-Off, which is provided in all modern tractors to transfer engine power to the attached implement. Different PTO driven machines require different PTO HP to operate. The PTO horsepower (HP) indicates the amount of power obtainable for running different tractor attachments. The PTO HP is transferred to the implements through tractor PTO shaft. Now what are PTO Shaft, PTO types and its uses? Let us understand in sections given below.
A PTO in a tractor is meant to provide power of the engine to a tractor implement or attachment like rotavators with the help of a PTO shaft. The driveshaft provides the rotational energy to operate a range of tractor-mounted implements. You need to have a PTO-driven implement to use the PTO of a tractor. There are PTOs of varying capabilities to transfer suitable power to the implements. Farmers cannot use implements like rotary slashers and balers without a PTO tractor. Such implements need a PTO tractor as they do not have their own engines.
The PTO in traditional tractors came without any protection. This was not a safe practice as the transmission system was prone to more damage, mainly when heavy implements were attached to the PTO. A modern PTO comes with protecting the transmission system against damages while powering high momentum implements. There are standardized structures in modern PTOs for universal compatibility and safety purposes.
The PTO stands for Power Take-Off. In 1918, the International Harvester Company introduced PTO in tractors. Its 8-16 model had the first commercial PTO. Edward A. Johnston, an engineer in this company, invented the tractor PTO. He also designed implements that can benefit from PTO with his colleagues.
The company came up with another PTO tractor in 1920, a 15-30 model, which became the first PTO tractor to go through the Nebraska tractor test. Eventually, other tractor companies started to implement PTO in their vehicles, and PTO became a mainstream component.
The PTO, as understood, transfers the mechanical power of the tractor engine to the farm implements. The power is transferred by joining the driveline shaft (connecting rod) of the implement to the PTO shaft of the tractor. So, when the engine starts, the driveline shaft rotates giving a rotational force to the implement attached through the Universal or ‘U’ joint to the PTO shaft. As a result, attached tractor implements start working. The point to note is that only those implements require PTO that needs rotational force to operate.
A tractor PTO shaft is a key component of a power take off as it transfers energy from the engine to the PTO-powered implement. With the help of it, a tractor can power all the implements requiring rotational force like hay rakes, balers, and threshers, among others.
PTO is an essential part of all modern tractors. This key part has a standardized structures for universal compatibility and safety. Its main parts are telescoping driveshaft, yoke at the tractor, and yoke at the implement. All these parts are covered with a PTO shield and is not visible. The PTO shield is used in modern tractors to protect tractor PTO shaft from getting damaged.
Broadly PTO can be divided into types, namely, Live PTO and Independent PTO. Let us see in brief what are they and their benefits.
This PTO type takes the help of a two-stage clutch. The power take off can be controlled by engaging the clutch. If it is pressed halfway, only the transmission will stop, and PTO continues spinning under a load. On pressing the clutch fully, the PTO also stops working. It is beneficial for mowing as farmers can stop the tractor and change gears while power is continuously sent to the mower.
Without a live PTO, implement will not receive power when the clutch is engaged. As the transmission and PTO are directly connected, an overrun clutch is needed for using high momentum implements. Simply, a live PTO separates the transmission’s control from the PTO operation control.
Even with the disengaged transmission, the tractor PTO shaft continues to work. Due to this feature, the risk related to the switching of gears is removed. It is mainly because the tractor PTO shaft does not stop when switching gears.
Therefore, there is no interruption in work when farmers switch gears. For example, if you are mowing a thick patch of grass, you have the freedom to stop or slow down the tractor while the implement is processing the thick brush.
An independent PTO or IPTO is a more advanced alternative to a two-stage clutch PTO. Farmers can run the PTO even if the tractor is not moving. This is because in this PTO type, the power take-off and transmission clutch works independently. This PTO can be engaged with the help of a button or lever that controls the power take off.
In the tractors equipped with IPTO, the PTO will work irrespective of tractor being at rest or moving. As the PTO is not affected by the position of gears, a driver can switch gears on running PTO. IPTOs generally have a greater output power and are perfect for continuous operations.
Independent power take-off protects the transmission of the tractor from damage caused by the excessive spinning of the tractor PTO shaft. However, if the driver starts the power take off when the tractor is running at top speeds, there can still be damage to the transmission.
There can be two types of independent PTOs, namely, mechanically and hydraulic independent PTO. The PTO on both types can be engaged/disengaged with the help of an electrical switch. However, the mechanical one comes with a lever clutch along with the electrical switch. This lever is a safety device that prevents accidental engagement of the PTO.
Most farmers prefer tractors with IPTO because they offer not only protection but also ease of operation. In addition, the output power in such PTO tractors is high in comparison to transmission power take off. Furthermore, when a tractor with IPTO is mounted on a harvester, it can halt cutter bar action while the harvester is moving ahead.
Having discussed PTO types, it is important for you to understand different PTO speeds, viz., Standard 540 RPM, 540E, 750 RPM, 1000 RPM, RPTO, MRPTO, and GSPTO.
Economy PTO (EPTO) means a PTO speed of 540 RPM at the given maximum engine rated RPM (ERPM), say 1900 ERPM, without consuming more fuel. In other words, for a PTO speed of 540 RPM, engine need to operate at 1900 RPM, and at this PTO speed, the consumption is fuel is less. This PTO speed is ideal for normal farming tasks like puddling or running an alternator.
By standard PTO we understand a PTO speed of 540 RPM. It means the PTO of a tractor and implement driveline shaft rotate at 540 RPM (9 times per second) at the given maximum ERPM. In this 6-spline is required for a PTO. This PTO speed is ideal for all normal farming tasks like cultivating, ploughing, etc.
By Reverse PTO (RPTO) or 540R, we understand that the PTO and driveline shaft rotate at the speed of 540 RPM but in reverse direction. This is important to clear anything stuck in implements while operating. For example, while operating a rotavator sometimes crop stubbles or weeds get stuck creating obstruction in operation. To get clear of this RPTO is used.
The other PTO speeds are 750 RPM and 1000 RPM. These PTO speeds are generally not provided in tractors manufactured in India except few like Swaraj tractors. Besides, there are MRPTO and GSPTO. MRPTO stands for multi-speed reverse PTO and GSPTO stands for ground speed PTO. A point to note is that all the tractors coming with multi-speed PTO either have the combination of Standard 540 RPM with RPTO, or 540E with RPTO.
We hope that you have understood the PTO tractor, full form of PTO, PTO types and different PTO speeds. Besides, you also would have understood the uses of PTO. A PTO is a necessity in all modern tractors to operate an implement because without implement farming cannot be done.
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