GB569891A - Improvements in or relating to loading ramps or the like - Google Patents

Abstract

569,891. Loading vehicles. SHELVOKE & DREWRY, Ltd., and EDWARDS, C. K. Aug. 5, 1943, No. 12666. [Classes 78 (ii) and 78. (iv)] In ramps for use in transferring loads to or from a wheeled vehicle or stationary platform of the kind which are arranged to be turned upwards from the operative position through a dead-centre position to rest upon the vehicle or platform when not in use, two spring mechanisms are provided which operate respectively on each side of the dead-centre position to counteract the gravitational turning moment on the ramp. The vehicle 1, Fig. 1, which is a large lorry designed to carry another vehicle, is provided at its rear with two ramps 7 which are spaced apart and each of which is of sufficient width to take the wheels or tracks of the carried vehicle. Each ramp is provided with a shaft 10 which is connected by links 8, 9 to a shaft 2 mounted at the rear of the vehicle. These links are free on the shafts 2, 10 and have extensions 11 which are pivotally connected to tension springs 12, 13 secured to the ramp by pivotal connections. A cam 23 fixed to the shaft 2, Fig. 2, has a peripheral groove which receives a cable 20. One end of the cable is attached to a ring 19 against which bears a compression spring 16 mounted in a tubular structure 17 on the lorry. The other end of the cable is secured to the cam at a point beyond the end of the groove. An arm 28 fixed to the shaft 2 carries an adjustable bolt 27 which bears against an abutment 29 on the ramp. By this means the spring 16 exerts a turning moment on the ramp and assists its lifting when manual force is applied to the handles 30, 31. This moment decreases as the ramp rises, since the cam 23 turns with the shaft 2, but bears a substantially fixed relation to the turning moment due to gravity. When the centre of gravity of the ramp is vertically above the shaft 2, the cam is in engagement with a stop which prevents its further rotation and the spring 16 ceases to exert any pressure on the ramp. At the same point the rotation of the links 8, 9 about the shaft 2 is arrested by stops, and in consequence the springs 12, 13 become stretched when the ramp is turned beyond the dead-centreposition to lie on the vehicle. Specification 566,032 is referred to.