Hydrostat in (small) tractors

Hydrostatic transmissions, also known as hydrostatic transmissions, are becoming increasingly popular, especially for small tractors around 50 hp. In contrast, there is the classic manual transmission, which is also familiar from other vehicles. But what are the differences between the two types of transmission? And what are the advantages of a hydrostatic transmission? We will try to clarify these answers for you.

What is a hydrostat?

The hydrostat is a hydrostatic transmission. This means that there is no purely mechanical connection between the engine and drive wheels. Instead, the diesel engine drives a hydraulic pump that is connected to a hydraulic motor. This then drives the tractor's transmission.

What are the advantages of a hydrostat?

One advantage of the hydrostatic transmission that immediately catches the eye is the elimination of the clutch: the transmission ratio is infinitely variable thanks to the continuous change in the delivery volume of the hydraulic pump and the displacement of the hydraulic motor. This is a great advantage, especially on slopes, as the flow of power to the wheels is never interrupted by the clutch, even when changing speed. In addition, the swivel angle can be quickly reversed and the direction in which the oil is pumped can be changed - this allows the direction of travel of the tractor to be changed quickly without the need for a clutch.

Another advantage is that the engine speed and speed can always be controlled separately. This is particularly useful when working on uneven terrain, as the speed can be adjusted individually without a sudden change in engine speed affecting the performance of the attachment. This also has a positive effect when working with the front loader - “ ‘stalling’, which can occur all too quickly with mechanical transmissions during front loader work, is almost impossible. In addition, a purely hydrostatic transmission has a compact size. This makes tractors with hydrostatic transmission particularly suitable for areas where there is little space for maneuvering.

What are the disadvantages of a hydrostat?

Of course, a hydrostatic drive does not only have advantages. One disadvantage of this system is that drag and slip losses can occur within the system, which means that the efficiency of the hydrostatic transmission is somewhat lower than that of a manual transmission. In addition, tractors with hydrostatic transmission are often somewhat more expensive than tractors of the same design with manual transmission.

Where else are hydrostatic transmissions used?

Hydrostatic transmissions are not only popular in compact tractors - a wide variety of vehicles are now equipped with a hydrostat. Smaller vehicles in particular, such as lawn tractors, have a hydrostatic drive, as this has a particularly positive effect on driving comfort. However, forklift trucks, telescopic handlers and yard loaders also often have a hydrostat.

But hydrostats are also becoming increasingly popular for large machines: Thanks to the constant improvement in the efficiency of modern hydrostatic transmissions, they are hardly inferior to mechanical transmissions in terms of performance. At the same time, they are often much easier to operate - which is particularly beneficial for large farms or contractors with changing drivers.