Tractor PTO: Types, Importance, Applications & Benefits of PTO in Tractors

19 Mar, 2024

Many people are familiar with the term "PTO", but not everyone understands what it is, what its uses or how it works. Read further to know everything about PTO and tractor.

What is PTO in a Tractor?

PTO is a device that supplies power from a tractor’s engine to an implement or machine that lacks an engine. Without the PTO, farmers cannot utilize the tractor power to operate implements like harvester, mower, and any other implement with no engine. You can easily find PTO in any tractor utility tractor, row crop tractor, compact tractor, heavy-duty tractor, etc.

Tractors with PTO were introduced in the tractor market in 1918 when the International Harvester Company added PTO to some production tractors. PTO then became an important part of tractors after it was featured in some models of tractors in 1918. The PTOs of old tractor models directly connected implements to the tractor’s transmission, but this resulted in more damage to the transmission, especially when high-momentum implements were attached to the PTO. Hence, Modern PTOs are designed to protect the transmission from damage even when energy is transferred to high-momentum implements.

Modern PTOs include standardized structures for safety and universal compatibility means. 

There are several ways to get power from the front power source and send it to associated implements. For transmitting power to attached secondary implements, this application generally uses a drive shaft and bolted joints. It's a mechanical gearbox that connects to the apertures on truck transmissions. This is a method of transferring mechanical power from farm tractors to tractor implements in a methodical manner.

Why are Power Take Offs (PTO) Important?

The PTO takes power that would have been wasted otherwise and supplies it over to implements used for performing farming operations. Hence, PTO plays a vital role in performing a variety of entirely necessary functions. For instance, towing cannot be done at the weight amount that it is without having power take off. Therefore, installing PTO in your tractor matters because of how much it can help you with different applications. In addition, it also acts as a power source needed to draw equipment for tillage and planting various crops. 

Applications of the PTO

PTO is used whenever an agriculture implement doesn’t have an engine to supply power. For instance, PTO is widely used and you often see it in commercial vehicles and farming equipment. The energy supplied by the engine through the PTO helps the implements perform heavy applications more seamlessly and effortlessly.

Examples of applications where PTO is used:

• Wood chippers

• Hay balers

• Harvesters

• Mechanical arms

• Water pumps

How does the PTO in a Tractor Work?

As we discussed above, PTO transmits power from the engine to an attached implement. But how does it work? 

The process starts with the shaft, the input shaft of the PTO taps energy from the tractor’s engine and supplies it to a hydraulic pump. Further, this hydraulic pump utilizes the energy to develop pressure. The pressure then forces the hydraulic fluid to flow until it reaches hydraulic equipment, where it generates energy. Moreover, PTO can operate implements like cotton pickers, mowers, and harvesters.

There are many types and series of PTO shafts that exist, but a PTO can only work with implements that match its shaft type. In addition to this, many PTOs transmit energy faster than others, PTOs on large tractors usually work faster and more efficiently than the ones on small tractors.

Types of PTO in Tractors

1. Transmission PTO

A transmission PTO is directly connected to the tractor’s transmission system. Through this, a PTO can supply power to attached equipment while the gear is engaged.

Furthermore, the Transmission PTO system is the simplest and basic type of PTO. Thus, its simpler structure can cause issues while operating the PTO with a high-momentum implement. As the PTO is directly connected to the transmission, it can apply maximum force on the transmission if the attached implement tends to drive the tractor’s transmission.

However, this situation doesn’t occur in tractors with built-in overrunning clutches. These overrunning clutches will detach the PTO shaft from the driven shaft during the faster rotation of the driven shaft than the PTO shaft, protecting the transmission from damage.

2. Live PTO

In the case of Live PTO, it can directly transmit power to implements even when the gear is not engaged. Live PTO includes a separate clutch for engaging and disengaging the PTO. With live PTO, the driver can even change gears or stop the tractor with the PTO engaged. This becomes possible as the live PTO utilizes a 2 stage clutch.

Even if the live PTO has its separate clutch, it’s difficult to engage the PTO if the tractor doesn’t come to a halt. However, the PTO can become fully independent of the tractor’s motion once the PTO is engaged. Live PTO has one benefit over transmission PTO, it can protect both the tractor’s transmission and PTO from damages that result due to high operating speed. 

3. Independent PTO

Independent PTO is quite the same as live PTO. Independent PTO has its separate clutch, which can engage the PTO without engaging the gear. This type of PTO does not depend on any other function of the tractor. A user can even engage or disengage the PTO while the tractor is moving.

Independent PTO has two subtypes, these are hydraulic-independent PTO and mechanical-independent PTO. hydraulic and mechanical both has electrical switch for engaging and disengaging the PTO. However, the mechanical-independent also has a lever clutch together with an electrical switch. This lever ensures that an operator doesn’t engage the PTO accidentally.
Moreover, a user can even change gears while the PTO is engaged as the place of the gears does not affect the PTO. Independent PTOs are suitable for consistent operations, and their output power is very high.

4. Economy PTO

It allows the tractor to run at a lower RPM of 540 while maintaining the same engine RPM. This saves gasoline, reduces vibration, and reduces noise. It's ideal for a variety of tasks, including baling, mowing, and tilling. The tractor should be set to 540 modes by default.

5. Reverse PTO

Every PTO type can rotate only in one direction, but they can be modified to reverse their direction of rotation whenever required. However one-way rotation doesn't create any issue while the PTO is supplying power to certain kinds of implements.

Whenever this process gets stuck, it can be resolved by changing the direction of rotation.

Moreover, the PTOs that can rotate in two directions are called reverse PTOs. Furthermore, all the PTO types can reverse their direction of rotation if a PTO adapter is available.

What is a PTO Tractor Shaft?

The PTO shaft transfers mechanical energy from agricultural tractors to implements. The PTO shaft is the energy that converts the engine's energy to hydraulic pressure. PTO Shafts require regular inspection because they are utilised to draw big weights and their absence can cause the PTO to malfunction. The PTO shaft is quite hefty; use it correctly.

PTO horsepower is determined in the following way:

The output shaft RPM is directly proportionate to the PTO's horsepower. As a result, the higher the speed of the turn, the more horsepower is produced. The formula for calculating a tractor's horsepower is as follows:
HP = Torque (T) x Rated RPM ÷ 5,252
 
PTOs are rated based on their torque capability, which is the amount of force required to move or run something. Here's the formula for calculating the PTO's speed:

PTO Speed = Equipment Speed + Engine Speed

Do all Tractors have a Power Take-Off (PTO)?

A Power Take-off shaft is found on most tractors and connects to your implements to provide power. The shaft draws power from the engine, indicating the amount of power available to operate various implements. When it comes to terrain, having a high PTO is also important.

Benefits of PTO 

PTO can help a tractor overcome and handle a variety of agriculture and commercial tasks. Thus, it becomes an important tool for farmers, landscapers, and anyone else who needs to perform operations in the yard or field. In addition, there are many other benefits involved, such as:

• PTO lets you use attachments that are complex and risky to power by hand.  

• PTO can also help you power a rototiller, which can benefit in loosening the tough soil, so you can prepare it for planting. 

• A PTO-powered tractor can save time you plenty of time and effort. For instance, if you want to clear a large area of field, You can do it by attaching a rotary cutter or brush hog to your tractor and letting the PTO do the work for you. This works more faster and easier than clearing the area with smaller powered tools.

• PTO also brings more power and offers an extra power boost, resulting in increased torque. It can be beneficial in high-force tasks such as plowing or tilling.