The Twin Terrain Mobility Tactical Vehicle (TTMTV) is a futuristic solution to the mobility restrictions of tracked vehicles (a.k.a. tanks) experienced in the Defense industry. It is generally known that wheeled vehicles lose traction in terrains such as mud, sand and snow. Tracked vehicles do much better on these terrains. However, tracked vehicles are incompatible with paved surfaces, as either the tracks damage the pavement, the pavement damages the tracks, or a combination of the two. Hence, when tanks need to be transported even short distances over paved roads, they need to be loaded onto special flatbed trailers and pulled by Class 8 semi-tractor trucks. The TTMTV eliminates this costly, time consuming and often dangerous process. In doing so, employing the TTMTV would enhance the Defense mission profile by the improvement in mobility.

The TTMTV on soft terrain appears as a common tank, with the droppable axles fully retracted. See Figure 1. However, upon exiting the soft terrain and entering a paved surface, the retractable wheeled axles are deployed. Initially the front steerable axle is engaged, lifting the forward track off the pavement while the rear of the track remains engaged on the soft terrain, providing drive traction. See Figure 2. Once the TTMTV is fully on the pavement, the rear retractable wheeled axles are deployed. See Figure 3. The rear axles can be single, tandem or even tridem, based on the gross vehicle weight.

The TTMTV design will accommodate space for the retracted axles. The TTMTV is wider that most tanks since the left and right wheels need to be far enough apart to provide vehicle stability during operation, as well as providing the needed steer tire clearance during maximum cornering. It is necessary for the axles to be contained inboard of the tracks for tire protection when retracted. The tire-wheel assemblies are equipped with a runflat insert, typical of tactical vehicles, to provide mobility even when a tire’s ability to contain inflation pressure is compromised. The retractable axles are deployed and retracted with onboard hydraulic power. When droppable axles are deployed, the tracks are raised to the point of required DOT commercial vehicle pavement clearance. Each wheel position is driven, including the front steers, as is common in tactical vehicles. Droppable tag (non-driven, non-steerable) axles already exist on commercial trucks, both on semi-tractors and rigid framed work trucks, which are deployed and retracted based on varying load conditions.

The TTMTV innovates with this technology by employing them on tracked vehicles, introducing the functions of steerability and making them driven. The drive power comes from the existing tank engine with an adaptable transmission. When compared with existing technology, the Twin Terrain Mobility Tactical Vehicle offers enhanced mobility, eliminating secondary transport vehicles and trailers, shortening mission time, requiring less manpower, and ultimately saving time and cost while improving chances of overall Defense mission success.