Track type tractors are different from wheeled tractors in that they are supported on the ground by a coiled circular track. The track contacts the ground, the spikes are inserted into the soil, and the driver is not grounded. Under the action of driving torque, the driving wheel continuously rolls up the track from the rear through the meshing between the teeth on the driving wheel and the track plate joint pin. The grounded part of the track exerts a backward force on the ground, and correspondingly, a forward reaction force Pk needs to be applied to the track, which is the driving force that drives the tractor forward. The driving force of a wheeled tractor is directly transmitted to the walking wheels, while that of a tracked tractor is different. Its driving force Pk is transmitted to the axle of the driving wheel through the track wound on the driving wheel, and then transmitted to the driving wheel through the tractor body. When the driving force is sufficient to overcome the rolling resistance and the traction resistance of the carried agricultural tools, the supporting wheels roll forward on the surface of the track, causing the tractor to move forward. Due to the driving wheel continuously rolling the track section by section to the front, and then laying it on the ground through the guide wheel, the supporting wheel can continuously roll on the track laid with the track. From this, it can be seen that the operation of a tracked tractor is achieved by the interaction between the track and the ground through the driving torque through the driving wheels, and the driving force is greater than the sum of rolling resistance and traction resistance.
The maximum driving force, like a wheeled tractor, depends on the ability of the internal combustion engine and is also limited by the adhesion conditions between the tracks and the ground. Generally speaking, the higher the power of a tractor, the greater the driving force. There are many factors that affect adhesion, and in terms of the structure of the tractor itself, a reasonable selection of spikes and the shape and size of the tracks, as well as increasing the weight of the tracks within a certain limit, can improve adhesion and increase the tractor's traction. The rolling resistance of a tracked tractor is formed by the deformation of the soil in the vertical direction and the mutual friction between the various components of the walking system. Reducing the rolling resistance can increase the tractor's traction.
