A tracked loader is an engineering vehicle consisting of a tracked chassis with a loader for digging and material loading. The history of track loaders can be defined by three evolutions of their design. Each of these advances has made the track loader a more convenient and versatile tool in the excavation industry. These machines are skilled in almost any task, but masters in none. A dozer, excavator, or wheel loader will perform a tracked loader under a range of conditions, but the ability of a track loader to handle nearly any task on a construction site is the reason many companies remain part of their fleet.
The first track loaders were built from crawler tractors with built from the ground up loaders. The first loaders were cables that worked like bulldozers of the time. These track loaders lacked the ability to dig on hard ground, but so are dozers of the day. They were mostly used to transport stockpiled materials and load trucks and wagons.
The first major design change in track loaders came with the integration of hydraulic systems. Using hydraulics to power loader linkages increased loader power. More importantly, loaders could greatly increase their ability to dig into compacted ground by exerting down pressure on the bucket. Most track loaders still relied on the equivalent of a bulldozer. The weight of the engine was still on the front half of the tracks, along with the heavy loader components. This caused many problems with excessive wear of the front idler wheels and undercarriage in general. The Caterpillar 983 track loader, the second largest track loader ever built, was notorious for heavy undercarriage wear.
The hydrostatic drive system was the second major innovation to affect the design of track loaders.
Track loaders have become very sophisticated machines that use hydrostatic transmissions and electro-hydraulic controls to increase productivity. Until the popularity of excavators increased, track loaders had little competition in terms of digging and loading jobs.