GB1423461A - Graduation of dials of measuring instruments - Google Patents

Abstract

1423461 Calibrating load-measuring instruments SNAP-ON TOOLS CORP 28 Feb 1973 9776/73 Headings G1J and G1W A method of graduating the dial 10 of a loadmeasuring instrument such as a torque wrench in which load is transmitted to an angularly moveable indicator 22 by a linkage comprising a pair of inter-connected angularly movable elements 11, 12 the angle E between which varies according to the applied load, comprises dividing the dial into notional load intervals and for each interval applying a correction factor based on the secant of the maximum linkage angle E corresponding to applied loads within that load interval, graduations 14 then being plotted around the dial in accordance with the corrected intervals. Further correction factors may be applied to the scale adjacent the zero mark to allow for frictional lag of the linkage, and to compensate for yield in the instrument when underload is shown in Fig. 5 the dial may have two opposing scales with a common zero, the indicator 22 having two arms 23, 24 one for each scale, each arm being settable to zero by rotation of the dial 10 until a pin 21 on the dial engages a notch 25, 26 in that arm. One arm and associated pointer in this case is used for measuring clockwise torque and the other arm and pointer for anticlockwise torque.