Patent GB-719953-A (GB)
Title: Condition-responsive instrument with setting and indicating mechanism
IPC: B64D45/00
Filed: 1952-03-24
Abstract: 719,953. Pressure gauges; indicating-apparatus. MELCHIOR, F. C. March 24, 1952, No. 7558/52. Classes 106 (2) and 106 (4) A condition-responsive instrument with setting and indicating mechanism in which a long tape having a calibrated scale thereon is movable longitudinally, and an operating mechanism is adjustable in relation to the position of the tape, has a single setting means, provided for setting the tape to a selected position and for simultaneously adjusting the operating mechanism in correspondence therewith, and actuating means responsive to a predetermined stimulus or condition adapted to co-operate with the operating mechanism to actuate the latter when the actuating means has responded to the stimulus or condition corresponding with the setting of the tape. An aircraft instrument for setting control mechanism to maintain level flight and for indicating the altitude to which it is set comprises a calibrated tape 87 wound on reels 95, 96, to which its ends are fixed, and passing over reels 90 (not shown), 85 to beneath a window 106 to indicate against indexes 108, 109, being driven by a setting knob 40 through worm 41 and worm wheel 80 causing the sprocket reel 85 to engage holes in the tape 87, with a spring interconnecting the hubs of the reels 95, 96 to prevent play. The worm 41 also engages a worm wheel 42 on a shaft 43 with worms at each end engaging worm wheels on threaded shafts 50, 51 upon which work the threaded ends of a contact arm 60 which is thus set to a position corresponding with the value on the tape 87 set against the indexes 108, 109. Capsules 15 sensitive to atmospheric pressure are connected by a spring strip 20 to a transverse spring strip 21 connected to an arm 22 pivoted by a spring strip 23 at one end and connected by a spring strip 25 at the other end to an arm 26 similarly connected to a second, contact arm 28 pivoted by a spring strip 29. The spring strips may be of beryllium copper or stainless steel and are sufficiently rigid to resist buckling under the force exerted By the capsules but sufficiently flexible to give when the arm 28.is depressed by the arm 60 if set to an altitude lower than its present level off flight. An electrical conductor 130 is connected through a supporting frame 11 and shafts 43, 50 to the contact arm 60 while 'a conductor 131 is connected to the other contact arm through the. strip 29, insulated from the frame 11. The contact arms 60, 28 are connected through the conductors 130, 131 and a relay to the servo unit of an automatic pilot which responds to the opening and closing of contacts 60, 28 with increase and decrease of pressure by maintaining when once reached the set altitude within small limits. The instrument may be adapted for signalling when an aircraft has fallen to a preset altitude by disconnecting the servo unit and connecting the conductors 130, 131 in an appropriate circuit so that breaking the circuit causes a visual and audible signal. The invention may be applied to a master instrument for calibration purposes. The instrument may be sensitive to temperature, voltage or amperage and the arm 28 may carry a magnet moving in an induction coil carried by the arm 60.