GB919536A - Improvements in and relating to steering mechanism for articulated vehicles - Google Patents

Abstract

919,536. Articulated vehicles; steering. CAMPBELL & McGILL Ltd. Nov. 7, 1960 [Dec. 30, 1959], No. 44307/59. Classes 79(3) and 79(5). A steering mechanism for a tractor-trailer articulated vehicle wherein the trailer portion is connected to a vertical shaft journalled for rotation in the centre line of the tractor comprises a linkage system for rotating the shaft whereby relative movement between the two parts of the vehicle is produced, the linkage including an arm pivoted on the centre line of the vehicle and connected through links to the shaft so that the rotation of the arm produces a greater rotation of the shaft. As shown in Figs. 2, 6, 7 and 9 of the Provisional Specification, an arm 9 of the trailer is rigid with a tubular member 10 mounted for pivotal movement by bearings 16, 17, 18 upon a post 12 rigid with a frame member 11 of the tractor. A driving shaft 13 is mounted in bearings 14, 15 in the post 12 and a member 19 (Fig. 9, Provisional Specification) is splined to the shaft 13 and has embossments 19a which engage. castellations in the top of the member 10 to form a driving connection with the shaft 13, the lower end of which is splined to a member 22 upon which are pivotally mounted arms 23, 24. A shaft 27 is rigid with the tractor frame, and pivotally supports a pair of shaped levers 25, 26 which are pivoted at their other ends to the, arms 23, 24. A pair of hydraulic cylinders 32, 33, controlled by valves 37, 38, are pivoted at 28 and 29 to the levers 26 and 25 and to a fixed cross member 36 of the tractor frame. The valve 38 is operated by a bell crank lever 48 pivoted to a pitman arm 50 and connected via a shaft 46 to the steering mechanism. Links 43 and 44 are connected to the control valves 37 and 38 and to bellcrank levers 41 and 42 which are connected by a link 45. The bearing pins 28 and 29 are connected by a link 39 recessed at 40 to bear upon the shaft 27. When a steering movement operates the valve 38 to move the arm 25 in one direction or the other, the link 39 moves the arm 26 and the links and levers 44, 42, 41 and 43 operate the valve 37 to operate the cylinder 32 in the reverse sense so as to assist the steering movement of the trailer relative to the tractor. Alternatively, a single steering arm and single hydraulic ram may be employed. In a modification, Figs. 2, 5, 6 and 7, the beam 9 of the trailer pivots by bearings 14 and 15 upon the shaft 13 to which it is drivingly connected by a lever 20 and anchor 21, the bearings 14 and 15 also serving to pivot the shaft 13 in the frame members 11 and 12 of the tractor. A quadrant member 22 is keyed to shaft 13 and is connected by links 23, 24 to L-shaped levers 25, 26 pivoted to a shaft 27. A pair of hydraulic rams 32, 33 is pivoted at each side to a frame member 36 and to, pivot pins 28 and 29, respectively, in the levers 25, 26. Fluid supply systems 37 and 38 are connected each to opposite ends of the ram cylinders 32 and 33 so that when pressure is applied in one system or the other, that pressure is applied to the one end of the cylinders on the other side to provide a turning torque on the shaft 13 whereby relative movement between the vehicle parts is produced to effect steering. A shaft 44 is connected to the steering mechanism and to a three-way valve 39 which provides for pressure in either system 37 or 38 or for locking both systems. The spool 40 of, valve 39 is connected by a ball joint 43 to the pivot shaft 28, movement of . the shaft 44 causing movement of the valve 39 relative to the spool/ and subsequent movement of the pivot pin 28 providing a follow-up movement. Any one or more of the steering cylinders may be disconnected. As in the previous embodiment, a single cylinder and single steering lever may be used. The link work system provides a magnification of the steering movement allowing the tractor part to be positioned at 90 degrees to the trailer part. The frame member 11 (in both modifications) is pivoted by pins 48 to the tractor frame 50, allowing, with the aid of stops, not shown, a 20 degrees relative movement between the parts for travel over rough ground. The trailer frame comprises side arm members 7 to which the tipping body 4 is pivoted at 8, the body being mounted on wheels 5. Tipping is effected by rams 46 which causes shortening of the wheel base, to facilitate which independent braking is provided for the tractor and trailer parts. Specification 919,537 is referred to.