Patent GB-555556-A (GB)
Title: Improvements in door and like fastenings
IPC: E05C3/16
Filed: 1942-07-03
Abstract: 555,556. Door latches. LINES, A. July 3, 1942, No. 9186. [Class 44] A pivoted hook latch has the latch and operating handle 10 on the inner or opening face of the door pivoted independently on a common pivot 2, the other operating handle 15 being mounted on a separate pivot 17, the arrangement being such that the latch is retracted !by pulling handle 10 or pulling handle 15. The latch comprises a radial arm 5 of U-section with the nose 1 riveted to the base of the U. The handle 10 is disposed between the sides of the U and has a short arm 11 engaging a pin 12 on arm 5 so that when handle 10 is pulled arm 5 is rocked clockwise to retract nose 1 against the action of a spring 9 which biasses the latch to engaging position Handle 15 has a shoot arm 18 engaging one end of a lever 19 pivoted at 21, the other end of the lever engaging pin d2 so that when handle 15 is pushed lever 19 rocks anti-clockwise, so rocking arm 5 to retract the latch. Retraction of the latch may be prevented by operation of finger pieces 22, 26, Fig. 4, on the outer and inner faces of the door respectively. Piece 22 is one arm of a three-armed locking member pivoted on pin 17. One arm 23 within the casing has an upturned end 25 which normally lies clear of the path of latch-arm 5, but when the member is rocked anti-clockwise end 25 engages behind arm 5 to prevent its release movement. The third arm 24 acts, inter alia, as a stop engaging the inner face of the casing to limit locking movement of the locking member. Finger piece 26 is one arm of a lever pivoted on pin 2, its other arm 27 normally extending along the casing wall as shown in full lines. When finger-piece 26 is rocked clockwise, arm 27 engages arm 24 and rocks the locking member into locking position in which, as shown in dotted lines, arm 27 abuts substantially at right-angles against arm 24 and so holds the locking member against release by finger-piece 22. Release can be effected by returning fingerpiece 26 anti-clockwise, during which movement arm 27 engages arm 23 and rocks the looking member clockwise to release position. If finger piece 22 has been operated to effect locking, the arm end 25 lies in the path of the end of arm 27 so that finger-piece 26 cannot be operated to effect release. Thus either fingerpiece may be operated to effect release only if the other finger-piece is in release position, and release can only be effected by the finger-piece which was used to effect locking. The finger-pieces are frictionally held against accidental movement by a plate spring 28 mounted on pin 21, its ends bearing respectively on arms 24, 27. The casing is inserted in a notch cut in the door edge and may be positioned by an end plate of usual type secured to the door edge by screws, or as shown in Fig. 3, may have webs 41 fitting saw cuts in the edges of the notch. The outer face has secured thereto, as by riveting or welding, a plate 37 secured to the door by screws. The corresponding plate 38 on the inner face is notched and slidably adjustable on the casing to accommodate different thicknesses of door, the edges of the notch having projections 40 which slide along corresponding grooves in the casing.