GB759050A - Improvements in and relating to blackboards and the like - Google Patents

Abstract

759,050. Blackboards. UNIQUE BALANCE CO.. Ltd. (Buisbank, N. V.). Feb. 11, 1955 [Nov. 17, 1953], No. 31886/53. Class 146(2) A blackboard is mounted for vertical sliding movement on a guide or guides and supported by one or more spring balances each associated with one of the guides and comprising a helical spring 20 which is wound or unwound by the action of an elongated spiral member 19 when the board is moved vertically. As shown in Fig. 1, board 1 slides vertically on guides 5, 6 and boards 2, 3 slide vertically on guides 6, 7 and are hinged so that they may be folded over board 1. Sleeves 11 joined by bars 12 and adjustably secured to edge strips 10 on board 1 slide on guides 5, 6 packing 15 being interposed. The spring balances secured in the' guide as at 18 include a torsion spring 20, tension spring 21, noise-preventing rubber sleeves 22. and a lower sleeve 23 engaged with a bracket 24 extending through a slot 9 in the guide. Sleeve 23 which engages with spiral member 19 has, with bracket 24, a ratchet formation by which the torsion of spring 20 is adjusted. Boards 2, 3 are hinged at 30 to sleeves 29 similar to sleeves 11 but having additionally rubber rollers, mounted between pairs of lugs 33, which bear on opposite sides of the channel. Boards 2. 3 are held with wheels 37 engaging member 38 by a wheel 43 on a pivoted bracket 42 which is urged by spring 44 into operative position, the spring passing a dead-centre position as the boards are folded. An arrangement with upper and lower boards sliding one in front of the other is shown, a pair of parallel guides being arranged at each side, with one board moving on the inner guides and the other on the outer guides. Fig. 11 shows an arrangement for supporting a heavy board 55 on four spring balances 62 arranged two at each side of the board in parallel guides 54. Each corner of the board is detachably secured to a sliding structure comprising a pair of half sleeves 56, connected by plates 58, provided with felt linings 57, and arranged to slide on the inner slotted faces of guides 54, a rubber or like buffer may be fitted to the upper sleeves. Specifications 384,534 465,925, 648,989 and 648,900 [all in Group X], are referred to