| 摘要 |
<p>790,013. Steering vehicles. KRILANOVICH, S. Aug. 8, 1955 [Aug. 13, 1954], No. 22764/55. Class 79(5) The steering shaft of a camera dolly is associated with a cam and a cam-follower linkage, so that when the cam is held against rotation, at least one wheel of the dolly is steered on rotation of the shaft through the linkage, while when the cam and linkage are held against relative movement, at least one other wheel is steered on rotation of the shaft. In Fig. 2, each pair of wheels 16, 17, 18, 19 mounted on a vertical shaft journalled in the body 10 and individual wheels 16, 17, and the pair 18, 19 are steered by three separate chains passing over one of three sprockets on the steering shaft 12 which carries handle bars 13, 14 (not shown). In Fig. 4, the sprockets 31, 32, 33 are integral respectively with sleeves 27, 28, 29 concentric with the steering shaft 12, the innermost sleeve 27 carrying a slotted cam 38, Fig. 6 the cam follower disc 49 of which is attached to the shaft 12 by the bolt 48 and the actuator crank 46. The sleeves 28, 29 are each attached to the bolt 48 by a toggle mechanism, Fig. 6, consisting of cranks 51, 53 and connecting links 50, 52. The handlebar shaft 55, Fig. 4 may be rotated by hand to move a clutch shaft 54 downwards wfnich causes disengagement of the end of a bell crank lever 74 from between arms 78 bolted to the underside of the cam 38 and engagement of a cross pin 82 in notches 84 in a collar 85 which is fixed to the sprocket 31. This movement is only possible when all four wheels are parallel to the sides of the camera dolly when a pin 91 may pass through a notch 89 in a horizontal plate 87. With the lever 74 disengaged from the arms 78, rotation of the shaft 12 causes equivalent rotation of all three sprockets 31, 32, 33 so that the wheels all turn through the same angle and the camera dolly may be steered in a straight line in any oblique direction. When the clutch shaft 54 is in the upper position, the cam 38 remains stationary on rotation of the shaft 12 so that the front wheels 18, 19, remain in the undeflected position. The cam follower disc 49 follows the slot in the cam 38 and rotates the sleeves 28, 29, through different angles such that the normals 94, 95 to the rear wheels 16, 17 always intersect on the common axis 92 of the front wheels 18, 19. The end portions 43 of the cam slot are nearer to the shaft 54 than the base 42 of the slot so that as the cam follower disc 49 moves relative to the slot from its central position in Fig. 6, the angle between the cranks 51, 53 becomes more obtuse, the crank 53 rotating through a greater angle than the crank 51. The change from one mode of steering to the other is effected without the operator taking his hands from the handle bar shaft 55, whilst rotation of this shaft is normally prevented by a thumb operated spring detent which locks the shaft relative to a bearing sleeve 57 which is integral with a collar 58 welded to the shaft 12.</p> |
