Patent GB-881514-A (GB)
Title: Improvements in or relating to compulsory differential driving arrangements for steering vehicles
IPC: E01C19/48
Filed: 1960-03-15
Abstract: 881,514. Differential gear. BARBERGREENE CO. March 15, 1960 [Oct. 20, 1959], No. 9155/60. Class 80 (2). [Also in Group XXXI] The wheels or endless tracks on opposite sides of a vehicle, e.g. on asphalt laying machine are separately driven through a gearing system which includes means for continuously varying the ratio of the speeds of drive to the two sides so that the vehicle may be steered. High and low rates of variation of speeds are possible to provide quick and slow steering response. The wheels (or tracks) on each side are driven from the I.C. engine through a main clutch, main shaft 39 and drive transmission, the output shafts of which carry sprockets 49 connected by chains to the track drives. The transmission comprises the input shaft 39 driving a shaft 60 through bevels 57, 59. A shaft 67 is driven from the shaft 60 at very high, high or low speeds by bringing a slidable double pinion 74, 75 into mesh with either the internal teeth 79 of a gear 63 meshing with a gear 71, a gear 77 or a gear 76, the latter three gears being non- rotatably carried on shaft 67. Gears 80 are rotatably mounted on either side of the box upon bearings 81 coaxial with the shaft 67. The gears 80 mesh with gears 85, one carried on shaft 86 and the other on shaft 89, which, with its associated mechanism, is shown as being rolled forwardly about the shaft 86 for the sake of simplicity. Meshing gears 90 of equal size are mounted on shafts 86 and 89. The shaft 89 may be driven from a motor 101 through gear 110 and gear 90, or through gears 111 and 112 at high or low speeds. Rotation of shaft 89 rotates gears 80 in opposite directions. Sunwheels 71 are mounted upon extensions of shaft 67 and mesh with planets 73 journalled in the gears 80. Planets 95 are integral with planets 73 and mesh with sun-wheels 96 carried by shafts 97 upon the other end of which the sprockets 49 are carried. When the motor 101 is stationary, the sprockets 49 are driven at the same speed for forward or reverse parallel motion of the vehicle. By rotating the motor 101, the gears 80 are driven in opposite directions at high or low steering speeds depending upon whether gears 110 and 90 or 111 and 112 are in mesh and different rates of movement are imparted to the sprockets 49. The steering motor 101 may be an hydraulic motor supplied with fluid by a pump 139 from a reservoir 136 through a variable regulator valve 105 and valve 103, Fig. 6. A by-pass and pressure relief line 141 is provided. The steering column 113 rotates a shaft 120, Fig. 5, through chain and sprockets, the shaft 120 having a link 121 coacting with a link 125 to operate valve 103 and a cam 129 coacting with a follower 129 to operate valve 105. In the centre position motor 101 is still and locks the gears 80 for straight line motion. A movement of the steering wheel in one direction or the other causes a variation of speeds of the wheels or tracks on opposite sides of the vehicle proportional to the extent of turn of the steering wheel to provide steering movement. With the main clutch disengaged, the motor 101 may be used to turn the vehicle about its own centre.