Improvements in scale positioning or reference means for altimeters

摘要

381,443. Altimeters. KOLLSMAN, P. 47, Dinsmore Place, Brooklyn, New York, U.S.A. Feb. 10, 1932, No. 4016. Convention date, Dec. 10, 1931. [Class 106 (ii).] In an altimeter having indicating pointers and other fiducial reference means co-operating with scale graduations means are provided to facilitate the setting of the instrument for a certain condition with respect to which readings are desired. The setting movement causes a change in the respective readings the change being of opposite sign relatively to a zero or other initial mark on the scale. As shown in Figs. 1 to 3, the indicating and reference setting means are applied to an altimeter 11 rotatably mounted in a casing 12 on a stub shaft 14. The instrument has secured thereto an element 16 formed as a gear wheel and associated therewith is a hub 22 integral with a gear wheel 20. Rotatably mounted on the hub 22 is a pair of gear wheels 24, 26. The wheel 24 carries a wheel 25 connected through pinions 28, 29, 31 with the wheel 26. A pinion 42 associated with the pinion 28, 29 engages the internal teeth of a ring 35 which carries a reference index 36 that co-operates with the scale 32 secured to the hub 22 of the gear 20. The scale 32 is provided with an aperture 33 through which a scale 27 carried by the wheel 26 can be viewed. The denominational indicating elements of the instrument are constituted by pointers 43, 44 on a central spindle 45 and sleeve 46 interconnected by pinions 47 .. 50. The parts are held by a resilient split ring 39 and enclosed by a cover-glass 40 and split ring 41. The reference setting means comprises a pinion 54 on a spring controlled sliding shaft 52 operated by an external knob 53. When the knob is operated in the position shown in Fig. 1, the gears 16, 24 are rotated to set the pointers 43, 44, scale 27 and reference index 36 to the particular condition such as barometric pressure. By first pulling the knob so that pinion 54 engages all three gears 16, 24, 20 the rotation will then cause the dial 32 to turn with the instrument 11 as a unit so that there is no relative movement of the pointers and reference index. In this manner the instrument if on an aeroplane can be set to position the pointer 43 horizontally to aid in the maintenance of level flight. Removal of the screw 56 enables the pinion 54 to be moved to engage the gear 20 alone when it is desired to adjust the reference index initially to compensate for inaccuracies in the instrument proper. Modified arrangements of the dial, pointers and reference means are described in the Specification.