GB586143A - Improvements in linear dimension dial gauges particularly for use with hardness testing machines - Google Patents

Abstract

586,143. Hardness tests; dial gauges. WOODHEAD & SONS, Ltd., J., and BERRY, W. R. Aug. 1, 1944, No. 14642. [Classes 106 (ii) and 106 (iv)] In a dial gauge, which may be used for measuring the depth of an impression made in a hardness test, the plunger of the gauge is coupled to the movable pointer or dial through a clutch which is engaged after the initial load is applied, so that the impression due to the subsequently applied load only is measured. The plunger 6 embodies a rack engaging a pinion 8 on a shaft geared through pinions 9, 10 to a shaft 14 carrying the core member 21 of an electro-magnetic clutch. The sliding armature 24 of the clutch is normally held disengaged by a spring and is coupled to a spindle 16 carrying the pointer 25 through pinions 18, 19, mounted on a spindle 15, and pinion 20 on spindle 16. A second pointer 27 serving as a revolution counter is mounted on the spindle 15. The clutch coils 22 are connected to terminal 30 through the shaft 14 and the casing 2, and to terminal 31 through a brush 35 pressing on a ring 23 on the core member. When the initial load has been applied, a switch is closed automatically to connect the terminals to a source of current. Indicator lamps 39 are connected to the terminal 31 and to segments 33 over which is adapted to move a contact arm 26 mounted on the spindle 16. The outer lamps are coloured and if lighted at the end of the test indicate that the piece under test is too hard or too soft. A spiral spring 29 returns the pointers on removal of the load. A helical spring is provided to keep the plunger 6 in contact with the part the movement of which is to be measured. Two dial gauges in tandem reading .001 inches and .0001 inches respectively may be employed. Audible signals may be provided to draw attention to rejections. The contact arm 26 may be adapted to control feeding and withdrawal mechanisms and sorting of rejected parts. Hold-on or resetting switches may be provided to prevent disengagement of the clutch until the initial load as well as the subsequent load is removed. When a gauge with a moving dial is used, small windows are provided in the casing to expose only the readings concerend. Arrangements of the gauge and control switch in both a hydraulic and a dead load machine are described and shown. Specifications 140,165, [Class 106 (ii)], and 417,881 are referred to.