Patent GB-988746-A (GB)
Title: Tandem axle spring suspension
IPC: B60G11/34
Filed: 1962-12-17
Abstract: 988,746. Tandem axle suspensions. A. F. HICKMAN, and H. I. POPP. Dec. 17, 1962 [June 11, 1962], No. 47481/62. Heading B7D. A tandem axle spring suspension comprises tandem axles 28, 29 of which one or both may be driven, mounted on a walking beam 38 which is pivotally supported on a cross tube 56 to which is attached a "bolster" 65 which provides a support for two sets of coil springs, a longer set 72 of lighter calibre and a shorter set 73 of heavy calibre, the springs 72 supporting the vehicle body in the unladen condition and both sets being brought into play when laden. Light restraining springs 102 retain the heavy springs 73 in the inoperative condition. The springs are accommodated at their upper ends in a bracket structure 89 attached to the longitudinal frame members 26 of the vehicle and pairs of vibration dampers 130 are connected between the bracket structure 89 and the cross beam 56. The axles are yieldably mounted on the walking beams so that when the vehicle is negotiating a turn, a self-steering effect is obtained. Torque arms 140 which take up driving and braking forces are connected to the axles 28 and 29 and to vertical rods 141 and 143 respectively, the rod 141 being connected to a bracket 142 attached to the " bolster " 65 and the rod 143 being connected to the vehicle frame. The connections of both rods 141 and 143 to the torque arms 140 include resilient bushings. A radius rod 120 is connected through resilient bushings to brackets attached to the structure 89 and the " bolster " 65 to give transverse stability and the axles are located longitudinally by radius rods 114 connected through resilient bushings to brackets 119 and 110 connected to the " bolster " 65 and structure 89 respectively. The pivotal mountings of the walking beams 38 to the cross beam 56 include torsion-resistant resilient bushings 55 which are accommodated in a housing 58, 43, the lower portion 43 of which is formed in the walking beams. Each walking beam is of generally square section with stiffening plates 47, 48 and side plates 41 and each axle mounting comprises a housing 151, 152 mounted on side plates 158 through which pass bolts 184 which pass through windows 50 in the walking beam and bushings 183 welded to a triangular section member 181, 182 on the upper surface of which is affixed a rubber pad 180 which bears against the underside of the top plate of the walking beam section. Resilient pads 190 are interposed between the top surface of the beam 38 and a plate 159 welded to the side plates 158 of the axle mounting and extending longitudinally either end. Plates 160 are welded to the ends of the plates 158 and form seatings for removable guide and wear plates 161 which co-operate with corresponding wear plates 165 removably attached to backing plates 166 with interposed shims 168, the backing plates 166 being welded to sleeves 169 journalled on pins 170 attached to the walking beam. The axle seating includes a resilient bush 149. The guide plates are arranged as shown in Fig. 14 whereby, when the vehicle is negotiating a turn, e.g. to the right when travelling in the direction to the right of Fig. 14, the axles move from their initial positions A to the positions E and F.