NDRC ARMORED CAR PROJECTS

A model of the eight wheel Baker jumping vehicle

The jumping cycle of the Baker vehicle is illustrated above in the following steps: 1. Chassis squats, 2. Chassis accelerates upward, 3. Wheels accelerated upward, 4. Vehicle in air, 5. Chassis decelerated upward, and 6. Chassis rises to normal road clearance.

In the Spring of 1941, the National Defense Research Committee studied the development of a new series of armored vehicles. Referred to as the Turtle series, it included not only medium and heavy equipment, but also a highly mobile, lightly armored, vehicle suitable for air transport. A wheeled vehicle was considered to be necessary to meet the latter requirement and it was studied in two basic models. The larger, eight wheel, version was intended to carry a 3 inch gun while the smaller, four wheel, design was to be armed with a lighter weapon. The weapons under consideration included the British 17 pounder (3 inch gun) and the 40mm gun Ml. All wheels were powered on these vehicles and an hydraulic anti-recoil system was a feature of both designs. However, the most interesting aspect of the new vehicles was the method used to overcome obstacles and achieve good cross-country mobility. This was accomplished by a new independent suspension system which was designed to permit the vehicle to jump over ditches, fences, and similar obstructions. This suspension was capable of very high energy absorption and was designed to permit the chassis to squat and then be accelerated upward. The wheels would then be accelerated upward and the entire vehicle would leave the ground. Although no actual vehicle was constructed, a full scale test unit consisting of one wheel with its suspension drive, associated frame members, and hydraulic jumping apparatus was completed. Tests performed with this equipment indicated that a full scale vehicle using this design could clear a height of 49 inches or a ditch 47 feet wide at a speed of 40 miles per hour. However, under estimating the dimensions of the obstacle might have been disastrous. Although a variety of armament was considered, preliminary designs were based upon the use of the 3 inch gun for the eight wheel vehicle and the 40mm weapon for the four wheel design. The eight wheel car was designed with a wheel base of 189 inches, a width of 121 inches, and an estimated weight of approximately 20,000 pounds. The four wheel vehicle had a wheel base of 137 inches, a width of 121 inches, and an estimated weight of about 10,000 pounds. Except for the test apparatus, the program did not progress beyond the model stage. Design work on the jumping vehicle program was carried out by the Baker Manufacturing Company of Evansville, Wisconsin under OSRD contract OEMsr-524. As a result, these vehicles were frequently referred to as the Baker tank.