| 摘要 |
738,908. Track brakes. FLEXELLO CASTORS & WHEELS, Ltd., and TOOTH, A. C. March 12, 1954 [July 20, 1953], No. 20104/53. Class 103 (1). [Also in Group XXX] In a lock, sprag or jack for securing wheeled vehicles against movement, a tubular metal body portion 1 welded to a fixing plate 2 is secured to a truck or like wheeled vehicle, a metal tube 3, linearly slidable within the body portion 1 and provided with a large diameter disc 3a faced with a pad of friction material 4, comprises the ground engaging portion, and a spring 5 acting between the body portion 1 and the ground engaging portion tends to pull the latter out of engagement with the ground, a toggle lever mechanism interconnecting the body portion and the ground engaging portion so that in the locked toggle position the ground engaging portion is extended for engagement with the ground whilst when the toggle is unlocked the spring 5 lifts the ground engaging portion and retains it out of contact with the ground. In operation, when it is desired to lock the truck, the foot operating pad 8 is depressed from the retracted position, illustrated by the full lines in Fig. 1 into the dotted line position the upper bell crank lever 7 pivoting about the pair of lugs 6, secured to the body portion 1, to push the link 9, pivoted at one end to a lug 10 secured to the metal tube 3 and pivoted at the other end to the upper bell crank lever 7, downwardly thus urging the whole ground engaging portion downwardly from the body portion 1. The engagement of the pad 4 with the ground moves the body portion 1 and therefore the truck slightly upwardly to take a part of the weight of the truck. When the three pivots 17, 15, 16 of the upper bell crank lever 7 and associated link 9 are in a straight line (i.e. the dead centre position) further movement of the foot operated pad 8 downwardly will lock the toggle linkage so that the ground engaging portion supports part of the weight of the truck. To unlock the mechanism, the foot operated pad 13 of a trip lever 11 is depressed so that the link 9 is moved outwardly from the ground engaging position and the linkage passes the dead centre position when the weight of the truck and the action of the spring 5 will collapse the linkage lifting the mechanism to the inoperative position illustrated by the full lines in Fig. 1.
|
