GB587587A - Improvements in comparator gauges - Google Patents

Abstract

587,587. Linear - dimension gauges. SIRVENT, P. B. Sept. 13, 1944, No. 17450. Convention date, Sept. 29,1943. [Class 106 (ii)] A comparator gauge for checking inside diameters or bores over a wide range comprises a frame 1, at least two measuring fingers 2 which can swing relatively to each other, each arm being secured adjustably to one end of an arm 8 which is pivoted at the other end to the frame 1 at 11, and means operated by the movement of each finger 2 for actuating an indicating-pointer 22a carried by a lever 22. The fingers 2 extend through a slot in the frame, one having a single and the other two ballgauging surfaces for engaging the work 46 carried by a vertically adjustable table 3. Each finger is bent at 45 degrees at its lower end, fitted into the boss 43 of a disc 4 which is adjustably secured to a further disc having a flange 6 to which is secured the arm 8. An extension 6a of the flange 6 engages a ball B mounted on a pin 17a adapted to slide vertically, against the action of a spring 19, in a fixed bracket 18. The indicating-lever 22 is carried by an arm 21 pivoted to the bracket 18 at 23, the other end of the arm having a sloping surface 20 co-operating under the action of a spring with the lower end 17b of the pin 17a. Movement of the fingers 2 is thus communicated to the pin 17a which moves the pointer 22a by engaging the sloping surface 20 of the arm 21. The fingers 2 can be pre-set to suit the size of bore to be checked by adjusting the discs 4 relatively to the other discs, a key being provided for this purpose ; the arms 8 are then locked against movement by means of transverse shafts 32 attached to the arms and passing through slots in the frame to receive locking nuts 33 (not shown). The pointer 22a moves under a window 26 and between two adjustable stops 30 which can be set to indicate the limits of tolerance of the bore being checked. The table 3, slotted to accommodate the fingers 2, is supported by a post which passes into the casing where it is adjustably clamped by a pair of hinged members. These members are held together when in the unclamping condition by spring clips mounted in grooves therein. A compression spring below the post counteracts the weight of the table in the undamped condition.