Patent GB-904448-A (GB)
Title: Improvements in or relating to tractors
IPC: B60N2/14
Filed: 1960-03-28
Abstract: 904,448. Tractors. PATENT CONCERN N.V. March 28, 1960 [April 21, 1959]-, No. 10889/60. Classes 79(1), 79(4) and 79(5). A tractor comprisesat least one steerable ground wheel adapted to be actuated from a s e a t through control means which together are turnable about a substantially v e r t ic a l axis and may be fixed in at least' two positions, the transmission mechanism coupling the control means and. the steerable wheel comprising at least two relatively rotatable parts of which a first part turns with the seat and the second is fixed relatively to the tractor, the steering control means including a control stick rockably mounted on the seat structure and pivotally connected to the first part of the steering: transmission. The chassis 1, 2, 3, 4 of the tractor carries three ground wheels 5, 6 and 7, the seat 14 being carried by a pillar 10 attached by plates 11, 12 to a shaft 13 which pivots about a shaft 15 carried by a structure including a plate 16 attached to the chassis member 4. A spring-loaded pin 18 carried by the pillar 10 may be entered into one of three holes 19 in the plate 16 to lock the seat facing longitudinally in either direction or in the position shown in Fig. 1. Levers 27 and 28 are pivoted at 22 and 23 to the stays of the seat, the levers being connected to a rod 31 attached by a sleeve 41, pin 40 and sleeve 39 to a rod 38 having a plunger 37 forming a dashpot mechanism with a cylinder 42, the rod and plunger being downwardly urged by, a spring 45 and formed with a bleed hole 38A. A lever 43 (Fig. 6) carried by the cylinder 42 pivots about a pin 34 carried by a bracket 36 attached to the shaft 16 and is attached to a rod 46 which passes through a tube 47 and is connected to a rod 51 which controls the hydraulic steering mechanism through a bell crank 52 and links 53 and 54 Fig. 8. A pump 73 supplies fluid, from a reservoir 74 to a pressure chamber 71 containing an air cushion 72 and to the valve 58 through a line 71A. A non return valve 73B and a pressure relief valve 75 are provided. The valve communicates with the reservoir through lines 74A and 74B and with the hydraulic ram 93 through lines 68A and 68B. Movement of the rod 51 in one direction or the other moves the valve spool 57 and operates the ram 67 which is pivotally connected by a rod 69 to a steering link 55. The link 55 is connected to the link 54 constituting, a follow-up mechanism, restoring the spool 57 to its neutral position at a given extent of turn and at its ends through bell cranks and links to steering arms 62 and 66 whereby steering movement is imparted to the wheels 5 and 6. Control pedals 77, 78 and 79 for the tractor are provided upon a platform 76 attached to the seat structure and operate their respective mechanisms through hydraulic controls 80. When the seat structure is in the position shown in Fig. 2, the vehicle is. steered by moving the handles 27 and 28 towards or away from the seat; and when the seat is facing in a longitudinal direction, the handles are moved sideways, i.e. the steering movements are always imparted by moving the handles transversely to the frame member 1 and in either longitudinal setting of the seat, a movement of the handles to the left causes a steering movement to the left in the forward direction of motion relative to the seat: Movement of the handles 27 and 28 rotates the shaft 31 and operates the steering mechanism through the sleeve 41, and members 39, 40, 38, 43, 46 and 51. The dashpot mechanism 37, 38, 42 compensates for changes in length required as the lever 42, 43 pivots about 34. There may be only one steering handle and several alternative positions of the seat in its rotation about the shaft 15. Specification 904,447 is referred to.