GB102498A - Improvements in Apparatus for Measuring Acceleration and Retardation. - Google Patents

Abstract

102,498. Carlier, J. G. Nov. 27, 1916. Acceleration and retardation, measuring; with means for controlling motors.- An apparatus for measuring the acceleration or retardation of a moving body comprises two masses rotating about the same axis, the centre of gravity of one being above and the other balow the suspension, so that the upper body is unstable and the lower in stable equilibrium, means connecting the two masses whereby the movement of one resists the movement of the other, and indicating or actuating devices operated by the relative movements of the masses. Fig. 1 shows a form in which one mass comprises a body of mercury in the U-shaped trough 6, 7, and the other a mass P mounted on a rod fixed to a shaft o carrying two arms f, to which are attached curved rods A, B dipping into the mercury. On an acceleration or retardation taking place, both the mass P and mercury move in the same direction, the movement being resisted by the increased immersion of the rods A or B, and the amount of movement being a function of the acceleration. In order to measure this, the arms A, B are wound with resistance wire and placed in the arms of a wheatstone bridge, the disturbance of the balance of which is either measured directly by means of a galvanometer or is utilized to actuate brakes, engine valves &c., or integrating devices by which an indication of the speed is obtained. Fig. 4 shows a form in which the masses A, B are both pivoted at O, the relative movement being resisted by means of springs R. R'. Where it is desired to indicate the acceleration in two directions at right-angles, for example on aircraft, a mercury trough having four arms a, d, Fig. 7a, is provided, and the mass P<1> mounted on a universal joint. In this case, the arms may be connected to the arms of two wheatstone bridges, the galvanometer circuits of which are connected to the coils of a galvanometer having two windings at right-angles; the reading of which thus gives the resultant acceleration. In order to indicate the inclination in space of a body, the apparatus is arranged as shown in Fig. 10, in which the coils 1, 2 immersed in the mercury trough are connected to one wheatstone bridge, the galvanometer circuit of which is connected to the coil I of the galvanometer G, while the coils 3, 4 in the pendulum arm are connected to another wheatstone bridge, the galvanometer circuit of which is connected to the coil 2. The resistances of the coils 1, 2 will be varied by gravity and acceleration, while those of the coils 3, 4 will be varied by acceleration alone. The coils I, II are arranged in opposition so that the resultant effect on the galvanometer will be due to gravity alone.