Torsion-type rubber suspension for bogie applications
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FURTHER information regarding the White Velvet Ride rubber suspension system to be manufactured in this country by the Holset Engineering Co. Ltd., Turnbridge, Huddersfield (COMMERCIAL MOTOR, December 1 1967) reveals that it is of the type mentioned in the Technitopics article published on November 25 1966 in CM. The suspension was developed by the White Corporation of Cleveland, Ohio, USA, for application to the tandem axle bogies of prime movers and trailers
Initially, components will be imported from America for evaluation purposes. They will be supplied to British users on a sale or return basis.
Disp I acement/periodicity performance curves of the system show that in a typical case, a periodicity of less than 120 cycles/ min, corresponds to a deflection of 2.75in. compared with periodicity/deflection values of 165/240 cycles/min and 0.75/1.25in. respectively in the case of conventional steel. leaf-spring systems. Only one basic design is currently available, but the rated load can be varied up to 18 tons—by using the appropriate rubber compound. It is claimed that virtually no maintenance is required.
Two spring units are employed in the system and each comprises a central torsion-bush assembly, attached to a special chassis cross-member, from which two radial arms extend forwards and rearwards to rubber bushes attached to axle brackets. The system represents an important variation of the rubber-in-sheer-and-compression principle.
Referring to the accompanying sketch of an earlier system which illustrates the principle, the left arm is bolted to a sleeve keyed to a torsion-bush spring which is mounted on a shaft fixed to the chassis, while the right arm carries the bush spring B which clamps on the same sleeve.
When the bolted arm is deflected upwards spring A is loaded torsionally and it also reacts on spring B to cause deflection of the rubber and to increase the load on the rear arm (referred to as the press arm) to an extent in each case dependant upon the initial load on the arm. Spring A is also compressed vertically which is an opera tional feature of the system. Longitudinal torque-reaction members and transverse tierods afford axle location. It is notable that only a proportion of the torsional loads is imparted to the frame members and that the suspension geometrically produces an appropriate steering affect when the body rolls or the vehicle is negotiating a curve. Four suspension dampers are included in the system.
The weight of the complete unit, including the cross-members, arms, torque rods and dampers is 9501b of which the cross member accounts for 2521b, the total unsprung weight being 3501b. Aluminium arms are being developed which it is anticipated will provide a saving of 3001b.
In comparisons of the ride characteristics of three articulated trailers, one with Velvet Ride and two with conventional systems, 38 shocks exceeding lg were recorded in the case of the vehicle with the rubber suspension as compared with 476 and 98 shocks of this order for the two vehicles with leaf spring suspension on a test over the same roads.