The PTS is a Soviet tracked amphibious transport. PTS stands for Plavayushchij Transportyer - Sryednyj or medium amphibious transport vehicle. Introduced in 1965, it is large, with a substantial payload of 10 tons, two to four times the capacity of the BAV 485, and better cross-country performance, at the cost of greater somewhat higher purchase costs because it is tracked. The most common model is the improved PTS-M that is powered by a 350 hp diesel engine. It has a boxy, open watertight hull, with six road wheels per side, front drive sprocket, rear idler sprocket, and no return rollers. Like the BAV 485, and unlike the DUKW, it has a rear loading ramp. The crew is seated at the front, leaving the rear of the vehicle open for a vehicle, which can be driven (or backed) in, rather than lifted over the side. To aid in facilitating this, the engine is under the floor.