The Mechanical Handling and Storing of Material

TRANSPORTERS, BRIDGE OR CANTILEVER CRANES 435 purchase with fall-block, and the other single purchase without fall-block. The former is shown in Figs. 611 and 612. In each case the traveller is held m position on the beam by the locking block b, whilst the load is being lifted or lowered, and, on the other hand, the load is sustained by the hooks K whilst the traveller is being moved along the beam. The locking block b and the sustaining hooks k are connected together by a system of levers and links in such a manner that the movement of the block B, in the act of locking the traveller to the beam, withdraws the hooks k out of gear with the fall-block ___which is then free to descend—and conversely, the movement of the hooks into geai with the fall-block effects the release of the traveller from the beam. An important feature is that the relative movements are so arranged that the movement of the block k into gear with the beam is almost complete before the hooks begin to withdraw from the fall-block, and, on the other hand, the movement of the hooks into gear with the fall- block is almost complete before the block begins to come out of gear with the beam. Also, although b actuates k to release the load, and k actuates b to effect the release Figs. 611 and 612. Showing Sliding Block and Traveller of Temperley Transporter. of the traveller, the final small movement to complete the locking of the traveller and the sustaining of the load is in each case forcibly completed the other way about. That is, the weight of the escaping load completes the revolution of the block b. and the forced revolution of the block b in coming out of gear with the beam forces the hooks into complete gear with the fall-block. It will be noticed that in both positions, Figs. 611 and 612, all the parts are securely locked by two pairs—lever and link—just over the dead centres. In Fig. 611 the fall-block is “home” in the traveller, and the latter is unlocked from the beam on which it runs, and can be drawn along the transporter beam, the load during its travel being supported from the hook marked k in the figure. Should, however, the hauling rope be paid out instead of being hauled in, pawl a catches on the notch, causing block b to rotate on its pivot, and its projecting tooth to engage in the large notch shown. The weight of the traveller, tending to make it slide down the beam, causes block b to begin to rotate into the position shown in Fig. 612, the rotation being forcibly completed by the weight of the load dragging down the hooks and forcing two pairs of