What Does PTO Stand For On A Tractor?

Tractor rear pto unit.

PTO stands for Power Take-off in a tractor. This piece of equipment may be a jackhammer or another implement that you attach to the tractor via the PTO.

If you’ve ever been to a farm or have engaged in farming before, you would surely get familiar with the PTO of the tractor. But what actually is a PTO? Well, it is a device that channels mechanical power to a piece of equipment. The piece of equipment doesn’t have its own power, nor does it have an engine or motor. Hence, it needs power from the tractor.

The very first PTO was presented by the IHC (International Harvester Company) in 1918. This company was the first brand that began manufacturing tractors with PTO. The PTO usually makes use of a drive shaft along with bolted joints for transmitting power to the secondary implement. It is a systematic way of transferring enough mechanical power from the tractor to the tractor implements.

How Does Tractor PTO Works?

Farmers were the first to invent the PTO to work in conjunction with the implement and the tractor. It converts engine power into rotational energy to power the implements. PTO comes in different types. If the PTO uses fluid to transfer energy, then it is right termed hydraulic. With the use of hydraulic, large implements can be moved using less power. For this reason, the PTO works well for the tractor. 

But how does the PTO achieve the transfer of power to the implement? Well, it is pretty simple. PTO input shaft taps energy from the engine of the tractor and transfers this energy to its hydraulic pump. This hydraulic pump utilizes the power to build enough pressure to move the hydraulic fluid until this energy created by this fluid movement reaches the equipment where it can do work. Hence, you can operate mowers, cotton pickers, and harvesters with ease using PTO. 

PTO shafts, however, come in different series and types. So, if you will purchase a PTO, you should ensure that the PTO you would buy would match the shaft type. Moreover, some PTO can channel more power than other PTOs. These more powerful PTOs are usually found in large tractors, and they are more efficient and work faster.

The earliest and simplest PTO was the transmission PTO. This PTO has its shaft connected to the tractor’s transmission directly. This PTO only works when you release the clutch.

Understanding the PTO shaft

PTO shaft is the shaft that transfers power to the PTO-powered attachment. Without the shaft, the tractor will never be able to power implements like wood chippers, flail mowers, wood chippers, excavators, rotary tillers, and many more. The PTO shaft connectors are not yet standardized. This non-standardization of the connectors often leads to confusion and complications when you connect the PTO shaft. 

For example, you will find the connection flange of some old tractor models near the tractor itself. This makes it difficult for you to connect it to the implement. This closer connection flange may be potentially hazardous to your safety. To prevent these connectivity issues, you can use a PTO adapter. This adapter extends your connection to your implement, providing extra space for your PTO shaft to rotate without hitting the arm weldment and other tractor parts.  

What is the PTO HP for?

The PTO HP refers to PTO horsepower. It shows the available power for running the different implements. At present, many implements necessitate more than 100 HP at 540rpm or 200 horsepower at 1000rpm. 

Yet, you would only find a few shafts that can channel this level of power. Remember that horsepower is not tantamount to torque. It is only a function of torque. In short, PTO horsepower refers to the horsepower at the PTO shaft. 

Understanding Tractor PTO RPM

To understand the tractor PTO RPM, you need to understand what RPM means. RPM, of course, means revolution per minute. Thus, it is a measurement of the rotating shaft’s speed. Tractor PTOs come with standardized RPM. Before 1958, most PTOs come with a 536 standardized speed. Later, the standard speed went up to 540 RPM. This increase in speed also increased the PTO’s output power sans increasing the noise and fuel consumption. 

You will figure out the tractor’s PTO-rated rpm by checking its PTO shaft. If the PTO shaft measures around 1-3/8 inches and comes with six splines, it means that its rotating speed is 540 rpm. Those PTO shafts—designed for a rotating speed of 1000 rpm—usually measures 1-3/4 inches and features 20 splines. It can also measure 1-3/8 inches with 21 splines. 

You can calculate the PTO rpm if you know the engine speed. Most tractors, of course, won’t give you quickly the PTO rpm. But most tractors come with a tachometer for measuring PTO speed and engine speed. So, if you have the engine speed, you can arrive at the PTO rpm because the PTO rpm is just a percentage of the rpm of the engine. The tachometer, however, will provide you the measurement of the engine speed that will turn the said PTO at the standardized speed.  


Safety Practices When Operating the Tractor’s PTO

Statistics show that serious injuries do occur when the PTO shafts get separated while the PTO of the tractor is engaged. This shaft is a telescoping shaft with one part sliding onto the next part. These accidental separations may not be commonly happening. But shaft separations do happen if the hitch is not correctly mounted. 

Such a separation of the shaft occurs when the hitch accidentally uncouples or breaks. So, when engaging the PTO, you need to be wary of this risk, for it may cause injuries. Below is a rundown of the safety tips to prevent PTO’s accidental separations and disentanglements:

  1. Make sure that you keep your PTO system’s components guarded and shielded. 
  2. Check if your driveline guards are spinning or rotating. In this way, you can make it sure that the driveline guards do not get stuck to the PTO shaft.
  3. Make it your habit to walk around your tractor and visually inspect it before you start it. You should also inspect the implements you will attach to your tractor.
  4. Make sure that you only utilize those drivelines that the manufacturer recommends for your machine. Refrain from switching drivelines.
  5. You should disengage the PTO and turn off the engine of the tractor before you alight from the tractor. It will also help to make this a habit, especially before repairing, cleaning, servicing, or adjusting your machinery.
  6. Please don’t abuse the PTO shaft by observing proper usage of it. Refrain from tight turns. Besides, avoid excessive telescoping and keep it to the bare minimum. Slowly engage power to the PTO shaft. Moreover, refrain from over-tightening of clutches on your PTO-driven machines.
  7. Make sure that you properly set the drawbar for every machine. In this way, you can lessen driveline stress and accidental separation when traversing uneven terrain and making tight turns.
  8. Securely locked the PTO driveline onto the PTO stub shaft of your tractor. 
  9. Check the operator manual or get the advice of an expert to keep in phase your universal joints.

Do All Tractors Come with PTO?

Not all tractors come with PTO, but most of them do. Most of them feature a PTO shaft that you can connect to your implement. The shaft, as mentioned above, gets its power from the tractor’s engine, and it can run various implements. Most tractors, of course, come with the rear-mounted PTO, which is a standard for most. But you will also find midpoint PTOs for some tractor models with forty to fifty horsepower capacity.


Conclusion

Understanding which type of PTO is best for your needs is a bit mindboggling, especially if you are a newbie. Moreover, PTOs vary in both direction and size, so it will be a bit confusing when you are shopping around for a tractor with PTO. Besides, the tractor’s standard direction of PTO is clockwise if you are standing behind your tractor. Yet, some models spin counterclockwise, so if you have UK implements, such a counterclockwise-spinning tractor is no good for these UK implements. 

You can check, for example, Kubota B6000 for this type of tractor is a counterclockwise-spinning one. Its engine turns in the opposite direction, so its PTO output is likewise backward. You can also buy converters; nevertheless, the converters may be pricey. So, if you don’t want to buy a converter, you might as well avoid these types of tractors.  

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