Tracked vehicles include conventional dozers, high tracked dozers, high tracked "skidders", soft tracked skidders, and also the tracks over bogie tire options. Each of the specific models of tracked skidders have slightly different performance characteristics. Each also fit into a unique niche when it comes to steeper slope logging.
Tracked skidders can work on slopes that are 10 -15% slope steeper than conventional rubber tired skidders. The absolute slope that a hard track vs a soft track machine can effectively work on is about the same.
Hard track skidders (dozers) involve a solid rail which provides support to the tracks bearing pressures, and a drive sprocket which powers the track by pulling it. Soft tracks involve a series of torsion spring suspended road wheels supporting the tracks bearing pressure, and a drive sprocket which pushes the track.
One of the main advantages of the soft track system is higher speed. This is due to it's suspension. As a result, soft tracked skidders can skid productively further than a hard tracked machine. Similar productive distances can be achieved with soft tracks as that with conventional rubber tired skidders. The main drawback however is the additional expense of track and suspension components replacement and repair. As with most equipment parts, soft track life is highly dependant on the conditions to which it is operated in.
One of the main advantages of hard tracks is the ability to use the machine in multiple applications, such as general excavation and road construction. Hard tracks are limited to a productive distance that is about half that of conventional rubber tired skidders, 7- 800 ft. However, alignment of the skid trail will determine as much as distance the effective productivity of skidding with hard tracks.
Tracks can serve a very important function under certain terrain and timber logging conditions. By bunching on the steeper slopes for rubber tired skidders, the effective slope that conventional logging can work on can be extended. This system, a swing system, however involves skidding twice with the associated costs.
In order to implement a tracked skidding system effectively, first involves strategic level logging planning to determine if the system would provide the cost advantage over other logging systems. It is at this point that the quesitons of how big, what type, how much, what cost, what impact can be answered. However incorporating a tracked logging system will be the most cost effective if the terrain to be logged contains a pattern of slopes in the 35 - 45 % range which are accessed by more gentle slopes. Implementing a strategic logging plan is the only way to answer this question.
Managing a tracked logging system, or any specialized logging system, can only be accomplished through effective logging planning. In this manner specialized logging systems can be targeted for only the tracts and portions of tracts that they can effectively work. Probably more importantly, it is keeping the specialized system off of the tracts that it does not fit.