What is TUZ? Surely all farmers with more seniority know this. However, those who are just learning to drive and operate a tractor will be happy to read our article about the three-point hitch, finding here the answer to the question: “why is it worth knowing how to use it?”

TUZ – a handful of stories

The first steam-powered agricultural machines were commonly used for plowing, as this activity was characterized by the most demanding nature of the work. Steam machines could not be used for every type of activity due to design limitations. Only a significant development of technology allowed them to be aggregated with functional accessories. It was then noticed that mounted machines became more efficient than trailed machines. It was the suspension of the machine that gave it greater maneuverability, traction and lower weight.

Obtaining the maximum efficiency of this type of combination of tractor and machine, however, required the development of a special system that would allow changing the position of the machine depending on the terrain. This difficult task was accomplished in 1925 by Harry Ferguson, who patented the hydraulically controlled, three-point hitch system (TUZ). This system already had what we would now call power regulation – the ability to sink the plow depending on its resistance. Ferguson’s three-point hitch, after many modernizations and modifications, has survived in its basic form to this day.

Functions and construction of the three-point hitch

The basic tasks of the three-point suspension system include:

• modification of the height of the suspended machine in relation to the tractor,
• the possibility of proper plunging/deepening,
• available transport location,
• stabilizing the implement in relation to the tractor,
• change of the depth of the machine depending on the working resistance.

The three-point hitch consists of two main parts:

• mechanical – suspension system,
• hydraulic – lift.

Mechanical part

The mechanical part of the three-point hitch is a lever system, connected on one side to the tractor, and on the other side to the implement. This system has its lower links and upper link. The lower links and the upper link are terminated with elements connecting the three-point linkage with the accessories (usually in the front part of the machine there are pins used for connecting with the links and the link). The operation of the hydraulic cylinder enables lifting the lower links – the piston rod of the cylinder is connected to the arms, which raise the lower links via hangers. The upper link serves both as a fastening element, but also allows the machine to be leveled relative to the tractor (thanks to the so-called turnbuckle).

Hydraulic part

The hydraulic part of the three-point hitch (also known as the internal hydraulic system) in the most basic version consists of an actuator (it is responsible for lifting), a pump (the source of pressure in the system) and a distributor (controls the oil flow). Many hydraulic systems also contain a safety valve that opens when the pressure is too high (e.g. when the lifting capacity is exceeded). This prevents damage to the system. Lifting the implements suspended on the three-point linkage is achieved by overriding the distributor – in this way we connect the appropriate oil flow channels. It is then directed to the cylinder chamber, allowing the piston to extend, and as a result – to raise the lift arms and lower links.

Lowering is also possible by overriding the distributor, but depending on the design of the system, it can be done in two ways:

• in systems with a single-acting actuator – switching the distributor consists in obtaining oil flow from the actuator to the tank; extrusion of oil from the cylinder is possible thanks to the force from the weight of the attachment,
• in systems with a double-acting cylinder – to lower the equipment, the distributor must be moved in such a way as to allow the oil to flow in the direction that will cause the cylinder to return (such a cylinder has two working chambers).

Check out our wide range today and take advantage of the full possibilities offered by LS tractors. Contact our dealer!