Patent GB-734048-A (GB)
Title: Undercarriage for vehicles designed to run over uneven ground and, in particular up and down stairs
IPC: B62B9/02
Filed: 1953-03-19
Abstract: 734,048. Facilitating passage over steps or stairs; rubber springs. AVE TRANSPORTMITTEL HOLDING AKT.-GES. March 19, 1953 [March 19, 1952; March 12, 1953], No. 7668/53. Classes 108 (2) and 108 (3). In an undercarriage for vehicles designed to run over uneven ground and up and down stairs in which the front pair of wheels is connected to the rear pair of wheels so that a rolling of the front wheels against a step of a stair causes an upward motion of the front wheels and a downward movement of the rear wheels, an elastic independent suspension for each wheel of each pair is provided without directly connecting the two wheels of the same pair by a rigid axle. As applied to a baby carriage, Fig. 1, in which an underframe 1 consists of a laminated spring at each side of the carriage, wheel-carrying arms 4 and 6 for front and rear wheels 5 and 7 respectively, are pivotally attached to the frame 1 and are interconnected by a link 10 pivotally connected between the free ends of levers 8 and 9 rigidly fixed to the respective arms 4 and 6. In operation, pull on a handle 16 to move the carriage up stairs, causes a lowering of wheels 7 and a corresponding raising of wheels 5, and a decrease in the distance apart of the two pairs of wheels, while maintaining the carriage in a horizontal position. For movement of the carriage downstairs, a cable 14 is manually operated to move the wheels towards one another, whereafter the wheels 7 are allowed to drop, while still maintaining the carriage horizontal. A mudguard for each wheel 5 is connected to the frame 1 by a link 19. In another arrangement, Fig. 8 (not shown), the wheel arms at each end of the carriage are connected together by a torsion rod journalled in the frame and the levers 8, 9 and link 10 are common to both sides of the carriage. As shown in Figs. 9-10, wheel carrying arms 41 and 6<SP>1</SP> are journalled in side plates 22 and carry lugs 25 which bear against rubber blocks 27 enclosed in sleeves 28, the front and rear sleeves 28 being interconnected by pairs of levers 81, 91 and a link 10. According to Figs. 12 and 13 (not shown) the arms 41 and 6<SP>1</SP> are interconnected by torsion bars each carrying two laterally projecting lugs which bear against rubber blocks enclosed in a sleeve as in the previous arrangement. In a modification of the arrangement of Figs. 9 and 10, Figs. 14 and 15 (not shown) the levers 8, 9 and link 10<SP>1</SP> are replaced by meshing toothed segments. Figs. 16-17 show an arrangement in the which front and rear wheels are sprung by torsion springs 36 and 37 respectively, the latter being interconnected by levers 81, 91 and link 101 movable by a pedal 40 mounted loosely on the torsion spring 36. Rollers 41, 42 co-operate respectively with the levers 8<SP>1</SP> and 9<SP>1</SP>. A locking lever 46 pivoted about the pivot point of the link 10<SP>1</SP> and lever 9<SP>1</SP>, rests in the locking position on a pin 48 and co-operates at its free end with stops 43 and 44 on a ratchet formed on the hubs of the lever 8. An inclined face 58 on a part 38 of the pedal is effective to free the lever 46 when the pedal is depressed. A ratchet wheel 49 rotatably mounted on the torsion spring 36 and loaded by springs 53 is provided with sets of ratchet teeth 50 and 51, the teeth 51 co-operating with a projection 52 on the part 38, to rotate the wheel 48 in the anticlockwise direction. The wheel 49 is retained on its central position by a fixed pin 55 which co-operates with one of a number of holes 54 in the wheel. In operation, depression of the pedal 40 to lower the front wheels, lifts the lever 46, frees the stop 43 and permits rotation of the lever 8<SP>1</SP> and the ratchet wheel. When the front wheels reach their lower limit, the lever 46 falls behind the stop 44 to lock the rear wheels. The pedal is returned to its original position by a spring. The wheels may be returned to their normal position by depression of the pedal 40 to rotate the ratchet wheel until one of the teeth 50 strikes the lever 46 to release the stop 44. In this position, the roller 48 rests against the lever 9<SP>1</SP> and upon return of the pedal, the parts are restored to the position of Fig. 16.