In other words /used/ travel final drives are planetary gears. They are applicable to all machines that run on caterpillar tracks. In excavators, there are always two travel gearboxes, far apart from each other, not forming a compact structure. They are mainly used to increase the torque and thus reduce the speed on the tracks.
In travel final drive, transmission is carried out using interlocking gears. Depending on the construction of the planetary gear we can distinguish the reduction sets of the first, second, and third order.
The operation of the planetary gear is quite often compared to the solar system, as the name itself suggests. The mechanism of action can be described as follows: In the center of the planetary gear, there is a sun wheel, and the others elements are circling around it like planets. When gears rotate around their own axis, the energy is divided into individual satellite wheels inside the carrier assy. These wheels transmit the energy to the next elements of the system.
Planetary gears are very popular because they allow you to freely change speed and rotation force. They are used especially in those machines that operate at high turns and are small overall dimensions. Their advantage is the multipoint drive transport. Thanks to which individual teeth in the toothed wheels are exposed to a lower load. This affects the life of the planetary gear.
For years the use of a planetary gearbox is the best method of drive transfer in tracked machines.
Travel final drive failure
Planetary gears are subject to frequent failures. This is for several reasons. Typically, some internal part of the travel gearbox is broken, for example, a shaft, intermediate gear, or seal. If we react relatively quickly and replace the broken part, then we should not have major problems.
If we ignore the symptoms – crackling, oil leakage, power drop – then we can bring about the total destruction of the planetary gear. Due to the scale of inside damage, it will not be possible to regenerate it. Or its costs will significantly exceed the purchase of used planetary gear in good condition. Used travel final drives are a very good idea if we are sure of the sources of their origin.
The most common cause of failure is the lack of transmission oil because it tends to outwear quickly. Lack of oil in the travel gearbox or its low condition causes seizure of bearings, wear of attacking rollers, deformation of teeth, and even bursting of the body. It is, therefore, necessary to constantly monitor its condition, because in this way we will avoid unnecessary damage.
The last of the key factors affecting the failure of the travel final drive is too much oil in the hub because owners or operators often fill the oil with the “full” method. When the temperature rises, the oil begins to increase in volume. This causes the seals to be pushed out, resulting in an oil leak or bursting of the body.
Seals should also be the control subject. Unfortunately, we have no influence of seals outwear which causes oil leakage and consequent seizing of the bearings. So, we just need to check regularly that our machine is working properly.