Important Tractor Terminologies You Should Know Before Buying a Tractor

Table of Contents

• All about Tractor Terminologies
  • Horsepower (HP)
  • Engine Capacity
  • Revolutions Per Minute (RPM)
  • Bore and Stroke
  • Torque
  • Torque, HP and RPM
  • Backup Torque
  • Specific Fuel Consumption (SFC)
  • Drawbar Power
  • PTO Horsepower (PTO HP)
• Conclusion

All about Tractor Terminologies

Are you planning to buy a tractor for the first time? Then it will always be overwhelming for you to understand the terms and technical jargon associated with a tractor. You may find the terms such as PTO HP, Torque, Backup Torque, etc., very confusing. Therefore, before visiting your nearest tractor dealer, go through the below information to decode the complicated tractor terminologies.

Horsepower (HP)

The HP of a tractor is the engine power output which a tractor engine produces.  It is a measure of engine strength, that is, how much work a tractor engine can do over a period. It determines a tractor’s ability to handle challenging tasks or heavier loads. It also determines how quickly a tractor can complete a task. So, the higher the HP, the greater the tractor’s ability to handle heavier loads and quicker will be the completion of a task. But you should choose a tractor according to your farm needs. For:

• Small Farms: 20-30 HP tractors
• Medium Farms: 30-60 HP tractors
• Large Farms: 60 HP and above tractors

Engine Capacity

The engine capacity refers to the total volume inside a tractor engine’s cylinders where fuel and air combustion take place. It is also called engine displacement. It is measured in Cubic Capacity (CC).

Generally, a larger engine is associated with powerful performance. But it is a misconception. Factors like engine design and advanced fuel injection systems can also enhance overall engine performance.

Revolutions Per Minute (RPM)

RPM stands for Revolutions Per Minute; that is, how fast the engine’s crankshaft is rotating in a single minute. It indicates how engine speed in combination with torque influences horsepower. So, you can either increase the RPM or the torque to increase the horsepower.

Also, if a tractor produces more power at less RPM, then the tractor can be considered highly fuel-efficient. Tractors generating maximum power at less than 2000 RPM are generally considered fuel-efficient.

Bore and Stroke

The bore of a tractor engine refers to the diameter of a cylinder in which the piston moves. It measures the inner diameter of the cylinder in millimetres (mm). The bore determines the combustion chamber’s size where the air-fuel mixture is ignited.

The stroke refers to the linear distance the piston travels inside the cylinder. It is the measurement from the piston's top dead centre to the bottom dead centre. The distance travelled is called stroke length and is measured in mm. It determines the engine's capacity to move air-fuel mixture within the combustion chamber.

Now, the bore-to-stroke ratio is critical for figuring out how the engine works. It is the ratio of stroke length to bore diameter. However, it is greatly influenced by the engine design and the use of the tractor.

Torque

Torque is a twisting force that causes motion in an object around an axis. It is the force initially required to do the work. It is the product of perpendicular distance from the centre of the axis (lever length) and the force applied at that distance. It is measured in Newton-meter (Nm).

To understand torque, let’s take the example of torque wrench that is required to tighten or open the nut and bolt. In this, opening the bolt by catching the wrench at a distance nearer to the axis requires more force to be applied but at a distance farther from the axis requires less force to be applied.

Moreover, in a tractor, torque acts on the drive shaft when it rotates and is the most effective at low engine speeds as it provides efficient operation with more towing power from a standstill.

Torque, HP and RPM

Torque and horsepower are directly related, but they are not the same. Torque does work, while horsepower measures the rate at which work is done. In other words, the work which you started with the help of torque, the horsepower enables you to quickly complete that work.

Furthermore, torque, horsepower, and RPM are also related to each other. With the increase in RPM, the torque and horsepower increase but up to a point. At higher RPMs, the torque will start decreasing, but horsepower will keep increasing, until the fall in torque is greater than the fall in RPM. This is because the engine must work harder to maintain a higher RPM.

Now, the question is whether to look at torque or horsepower while buying a tractor. A higher torque is required for puddling, tilling soil with hard pan or doing work without obstacles but if you have to complete work with speed on soft soil surface, then HP is required. It is best to maintain a balance between HP and torque while purchasing a tractor.

Backup Torque

Suppose you are pulling a fully loaded trolley, and your tractor is operating at maximum torque at low 3^rd gear. Due to heavy load, the tractor is dropping RPM, now what will you do? You will either shift to a lower gear at the cost of speed to provide more power or if the tractor has good backup torque, it will use it without lowering the gear.

So, when you are using more power, then the tractor is operating at peak torque. So, the difference between the maximum torque of a tractor and the torque it produces at the rated power is called backup torque.

Therefore, a backup torque is needed when a tractor is doing heavy work. It allows the tractor to absorb more load without any loss in productivity. A high backup torque in a tractor indicates that tractor is powerful, and you will be able to perform heavy-duty farm work without changing gears.

Specific Fuel Consumption (SFC)

The most important thing after horsepower which you should look for while purchasing a tractor is fuel efficiency. Farmers in India are especially concerned about how much diesel the tractor will consume while performing any farm task. To determine the fuel efficiency of a tractor, you should always look for SFC indicated on the body of most of the tractors.

SFC stands for Specific Fuel Consumption. It measures the amount of fuel used by tractor’s engine per unit of power (either kWh or HP).  Technically speaking, it is the ratio of the fuel consumed to the engine’s power output. It is an indication of engine’s performance and the tractor with lowest SFC is the most efficient. The most popular example is Mahindra 575 DI, which has the lowest SFC at maximum power.

Drawbar Power

While operating a tractor implement, you might have come across terms like engine power, PTO power, and hydraulic power. When the tractor uses engine power to move the tractor and implement through the rear wheels or tracks, it is called drawbar power.

PTO Horsepower

Power Take Off (PTO) in a tractor transmits the engine power to the farm implements that require rotational force to move. PTO is usually found at the rear of the tractor.

While transmission of power to the PTO, some power is lost due to friction and the available power to operate the PTO implements is known as PTO power, which is expressed as PTO HP. It is usually 4 –5 HP less than the maximum engine power. It is possibly more important than the engine power as it helps operate implements like rotavator or power harrow.

Conclusion

Understanding the basics of tractor terminologies is essential if you are planning to buy a tractor. This will help you make a better decision and choose an appropriate tractor as per your farming needs. So, the next time you visit a tractor dealer do ask for the test report of that particular tractor where you can find all these terms. Also, you can watch tractor videos on Tractorkarvan to understand these concepts comprehensively. For more technical information about tractors, explore Tractorkarvan right now.