GB270784A - Improvements in and relating to lever linkwork apparatus - Google Patents

Abstract

270,784. Murdoch, A. G. Feb. 3, 1926. Window blinds.-Relates to lever linkwork apparatus for supporting and moving into and out of operative positions shop blinds, &c. of the type in which a primary arm pivoted about a fixed axis is connected at its free end to one of a pair of toggle links the other of which is pivoted about a fixed axis, with means for operating the arm by opening and closing the toggle, and comprises the provision of a secondary arm carried by the primary arm on the same pivot as the toggle connection, with means for moving the secondary arm about the common pivot synchronously with the movement of the primary and toggle arms. An arrangement for supporting spring-roller shop blinds or awnings, shown in Figs. 1 and 2, comprises, at each end of the awning, a primary arm 39, a toggle pair 27,. 33 and a secondary arm 48. The lower toggle link 27 is mounted on a fixed pivot 28 whilst the primary arm 39 is swung upon a shaft 38 adapted to be rotated by hand or motor to close or open out tha linkage by driving through pinions 40, and bevel gears 43, 44, a shaft 45 mounted on the arm 39 and carrying or, through bevel gears, operating at its outex end a worm 46 meshing with a worm wheel 47 secured to the secondary arm 48 concentrically with the pivotal connection 34 of the arms. Also secured to the worm wheel 47 on the joint pin 34 is a sprocket wheel 35 connected by a chain 36 to a sprocket wheel 32 rigidly secured to the toggle link 27, so that the toggle is opened out from the position shown in Fig. 2 to that in Fig. 1 by the action of the chain gearing driven by the shaft 45 whilst the secondary arm 48 is unfolded. The blind or awning lath or support is carried by the outer ends of the arms 48 and the opening out movement may be limited by abutment lugs on the primary and secondary arms. The arms and links may comprise flat strips spaced by collars and secured on each side of the respective gear elements or they may be of channel, box or cylindrical form. The secondary arms may carry further arms opeated by an extension of the gearing. The gears &c. may be encased. The worm wheel 47 may be an annular segment co-planar with the sprocket wheel 35. In a modification the shaft 45 is mounted on the secondary arm 48 and is driven by a motor carried on the movable framework, the worm-wheel in this case being secured to the primary arm whilst the sprocket wheel is secured through its support to the secondary arm. The linkwork at each end of the blind may be operated by a single motor or by a pair of motors running in synchronism. The motors may be controlled by automatic switches actuated. by clockwork or by variations in the intensity of light, and may be automatically stopped and reversed at the end of the movement. Instead of being driven by the shaft 38, the movement of the primary arm about its pivot may be utilized to operate the gearing between the primary and secondary arms, the gearing carried by the primary arm co-operating, in this case, with a fixed segmental toothed rack.