Air Spring Experiments

New Zealand Herald, Volume LXXVI, Issue 23275, 18 February 1939, Page 14 (Supplement)

Air Spring Experiments

AMERICAN CAR COMPANIES INTERESTED

Experiments with air springs to, replace present leaf and coil suspensions have been made by one of the> largest American tyife companies during the last two years. The new system has not yet been adopted by any car manufacturer, but encouraging reports of its success point to the possibility of air springs becoming an inherent part of well-known makes of cars in a year or two. Air springs have been carefully tested on 13 different makes of cars, some with independent. ; front suspension, and others with a rigid axle. In all cases, the • new system can be applied-with little structural alteration, and gratifying results are said to have been achieved with each one. A great virtue of the device is its simplicity and freedom from mechanical joints subject to wear. As careful Bpring control is inherent in the design, knock absorbers are. eliminated. The car is supported on four rubber bellows, one at each wheel, each bellows being connected by a rubber hose to a steel reservoir concealed beneath the mudguard. The whole system is filled with air at about 251b. pressure through a fitting on the reservoir. One difficulty was the design of a rubber bellows capable of standing up to long usage. This has been solved by . reinforcing the bellows with two layers of cord fabric, as in a tyre. The most gratifying feature of the new system is that it gives soft riding at low speeds on city blocks with great stability at high speeds. The bellows can

be inflated in varying degrees to cope with different roads, while the motorist who requires a stiffer spring action than normal can easily obtain that by a simple adjustment to the air valves. In order to prevent undue rolling of the car on corners, each bellows is fitted with a simple pendulum-operated valve. Centrifugal force throws the" pendulums of the outer springs across so that the valves are closed. Air from the bellows cannot be forced back into the tanks, and rolling is checked. Lateral movement is further stopped by fitting a cross torque bar be-: tween chassis and axle/, at the .back, and fore and aft movement ia vPrer ; vented by the torque tube. if BUdH *IS fitted, or by torque'arms if it is not.