Polecat Mk II Terrapin

The Polecat Mk II "Terrapin" was an amphibious two-section tracked carrier, tested in 1960-1961. Its designer developed it alongside the non-floating Polecat Mk I, a two-section tracked carrier with aluminium bodies. The Polecat was adopted by the US Army in 1959 as a fast, high-mobility personnel carrier for Greenland, where it served for many years.

Design

The front section held the engine and a bus-type body, heated by the engine cooling system, for a crew of two and several passengers. It weighed 5,870 kg, including 450 kg of payload, and measured 5.7 m long, 2.4 m wide and 3.45 m high. A Chrysler V8 petrol engine of 110.4 kW (about 148 hp) drove through a Clark five-speed gearbox, a torque divider and automotive-type axles with a lockable centre differential. The front section could also run on its own.

The rear section was a cargo unit 6.0 m long with a 4.2 x 2.4 m platform for 2,720 kg of load, weighing 5,440 kg in all. Each track ran on four independently sprung road wheels with pneumatic tyres, carried on trailing arms with hydraulic springing. The 890 mm wide tracks were built from rubber belts reinforced with nylon. Hydraulic cylinders steered the vehicle by turning the sections up to 35 degrees each way, and another cylinder let the front section pitch 35 degrees up or down relative to the rear.

Performance

Average ground pressure at full load was only about 0.12 kg/cm2. The Terrapin reached 49.5 km/h on land and 4.8 km/h in water. Its minimum turning radius was 11.6 m, it climbed slopes of 31 degrees, and its maximum drawbar pull was 67.7 kN. Range on land was 160 km, with fuel consumption of 250 litres per 100 km.