GB1260241A - Improvements in and relating to assemblies such as drawings boards and supports therefor - Google Patents

Abstract

1,260,241. Clamps. F. G. R. LAWES. 21 Oct., 1969 [1 Jan., 1969], No. 121/69. Heading E2B. [Also in Division A4] A drawing board 16 is slideable perpendicular to its base line on supports 4 (,4A) and is locked in an adjusted position by a device comprising two channel elements 22, e.g. of aluminium alloy, on the board, cylindrical parts 32 on supports 4 (,4A) slideable in the channel elements 22 and a locking means 30, 31, (28), 29, Fig. 8A, located within at least one of the channel elements 22 and mounted on support 4. The locking means comprises a spindle 31 (see Figs. 3, 4, not shown) with an eccentric portion 31 Y and rotatably mounted on spindle 31 a metal sleeve 30 with an eccentric portion (30X). P.V.C. locking sleeves (28,) 29 are respectively mounted on a portion 31X of the spindle 31 with a central axis of rotation and eccentric portion (30X). Spindle 31 is initially set (by the use of holes and a set screw) so that the eccentricities of portions 31Y and (30X) nullify one another, (Fig. 6, not shown) and sleeve 29 is concentric with and does not touch channel element 22 so sliding adjustment is possible. On partial rotation of sleeve 30 on spindle 31 the eccentricities of portions 31Y and (30X) reinforce one another and sleeve 29 is pressed into contact with channel element 22 (see Fig. 7, not shown). Then the sleeve (28) is brought into contact with the channel element 22 in diametric opposition to sleeve 29 thereby producing a stable locked position. A control member 33 has a peg engaging in a hole in sleeve 30 to partially rotate the sleeve, and a rotary cylindrical member 34 parallel to channel elements 22 has pegs engaging holes in member 33 to move the latter transversely. Members 33, 34 are mounted on support 4 and member 34 has a square bore through which slideably travels a square bar 24 mounted on the board 16. The bar 24 is rotated to rotate member 34 by a handle 26, Fig. 1. Supports 4 (,4A) are pivotally mounted on a shaft 2, Fig. 1, connected between two base pedestals 1 and the board 16 is locked in adjusted angular positions by pawls 5 carried by supports 4 (,4A) and spring- loaded into engagement with notches 6 on pedestals 1. A wire 27 may connect the pawls 5 to the handle 26 for simultaneous unlocking 4 the slide-locking means and release of the pawls 5. As the board 16 is angularly adjusted wires 9 wind and unwind around a shaft 8 connected between the supports 4 (,4A), the wires 9 being connected to the pedestals 1 at 10. The wires 9 thereby alter the tension in a wire 14 which is conected at one end to a pulley 12 rotatably on shaft 8, passes over a pulley 15 rotatable on shaft 2 and is connected at its other end to the board 16 at 17 to support the weight of the board. The tension in wire 14 is produced by a torsion spring 11 on shaft 8, spring 11 being fixed at one end to pulley 12 and at the other end to a hub (13, Fig. 2), adjustably fixed to shaft 8. Two wires 18 attached to supports 4 (,4A) at 19 pass over pulleys 20 and are connected to the respective ends of an adjustable tension spring 21 to balance the board 16.