Patent GB-648432-A (GB)
Title: Vehicle spring suspension
IPC: B60G11/23
Filed: 1948-07-23
Abstract: 648,432. Vehicle suspensions. TWIN COACH CO. July 23, 1948, No. 19735. [Classes 108(ii) and 108(iii)] In a vehicle suspension. a torsionally pre-stressed spring member is provided, having relatively moveable connections with the sprung and upsprung masses of the vehicle, and arranged so that as the vehicle load is increased to the maximum the torsion in the spring member is reduced to zero. In the examples described, the spring member in question is a rubber bushed shackle connecting the main suspension to the frame, deflection of the shackle on maximum load reducing the pre-stressed rubber bushing to zero stress. Fig. 1 shows a driving axle 11 terminating in two gear casings 32 which are connected by a tie rod 33. Rotatably mounted on each end of the tie rod is the end 34 of a longitudinally disposed torsion spring, to which is rigidly secured the adjustable arm 45, whose other end is attached to the rubber-bushed shackle 12, the other side of the shackle being mounted on the vehicle frame. The angular adjustment in the arm 45 permits adjustment of the main torsion spring 34. Fig. 5 shows the spring shackle 12 in its unstressed position. Rubber is moulded in situ round the upper and lower arms 13, 14 of the shackle, preferably so that a thin layer of rubber extends between the flanges of the split housings 19, 20, the flanges on half housing of each pair being reinforced by metal strips 23. In the unstressed position the plane of the flanges of the two housings are parallel, but, as shown in Fig. 1, when the shackle is bolted in position, the rubber in the upper housing in particular is pre-stressed in such a direction that as the axle is depressed with increasing load, the torsion in the shackle is reduced. By this means the maximum torsion to which the shackle will be subjected is known, viz. that at no vehicle load, and the shackles cannot be stressed beyond their safe limit. In another example, Fig. 7, the main suspension spring is shown as a rubber torsion spring 116 secured across the axle 112, the ends of the inner member of the torsion spring 116 being connected rigidly to arms 158 which are connected to the chassis through prestressed rubber-bushed shackles 124. shown in cross-section in Fig. 8. The upper and lower sides of the shackle are formed with a number of flanges 132 which alternate with annular fins 138 formed inside the metal housing 134, the rubber being moulded in situ as before. This arrangement resists side thrusts on the shackles. In a further modification, Figs. 13 and 14, the arm 158 of Fig. 7 is replaced by an arm 1,000 which is secured to the main torsion spring 120 by a vernier adjustment compricing a perforated disc fast with the spring member and a second perforated annular member integral with the arm, bolts being passed though the two perforated members in the desired position. The arm 1,000 terminates in a yoke 1,200 to which is secured the inner member 1,060 of a rubber torsion mounting, the outer member 1,020 of which is secured to the vehicle frame. The inner and outer members, which are provided with flanges and annular ribs respectively, as before, are eccentrically arranged, the rubber being subjected to compression in addition to a reduction of the pre-arranged torsion, when the vehicle load increases and the arm 1,000 rotates.