New Anti-roil
Page 55
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Air Suspension
New Heavy-duty Air Suspension Developed in America by Kenworth Motor Truck Co. : Anti-roll Prop. erties Derived from Geometry
A NEW type of air-suspension system
for heavy-duty goods 'chassis has been developed by the Kenworth Motor Truck Co., Seattle, Washington, U.S.A. The system incorporates several novel features, and is known as the The design includes four heavy brackets, bolted to the chassis side members and cross-braced by pressed-steel channel-section cross-members. The brackets are mounted in front of each axle, with the air springs to the rear.
Trailing arms are secured to the brackets by rubber-insulated steel pins, and are rubber-mounted #6 the axles also, passing under the axle tubes. Shim adjustment at the pin end of each arm locates and aligns the axles correctly. The four arms are splayed outwards at the axle end by 2% and as the arm brackets are permanently attached to the axle tubes, each pair thus forms an antiroll linkage.
The complete tandem-axle suspension unit is attached to the chassis at eight points over a length of '8 ft. 3 in., and to conform with American requirements the design provides no weight transfer from one axle to the other within 5-,! in. of oscillation.
Rolling lobe a i r springs of fabric-reinforced Neoprene are located immediately to the rear of each axle, and the springs are con trolled by four heavy-duty telescopic dampers. The normal chassis brakingsystem air pressure is used and when the vehicle is empty the springs operate at 5/15 p.s,i., the pressures rising to 60/85 p.s.i. when fully loaded. Two levelling valves control the springs.
The handling qualities of the system are stated to be excellent, both the laden and unladen ride being comparable to that given in a light private car. There is fast response to roll, which suggests that the suspension would be suitable for double-deck. vehicles.
A Kenworth-six-wheeler equipped with the new suspension was recently supplied to a tanker operator, the vehicle being powered by a .G.M.C. 8V71 two-stroke oil engine .developing 290 b.h.p. The chassis has Timken driving axles, fourspeed main gearbox and three-speed auxiliary box. As with all current Kenworth normal-control vehicles, a tilting bonnet and front-wing assembly, made of glass-fibre, was fitted to this vehicle in its final form.