Patent GB-542231-A (GB)
Title: Improvements in or relating to linear-dimension gauges or comparators
IPC: G01B5/00
Filed: 1940-06-27
Abstract: 542,231. Linear-dimension gauges. SIGMA INSTRUMENT CO., Ltd., and LOXHAM, J. June 27, 1940, No. 10972. [Classes 106 (ii) and 106 (iv)] The movement of the anvil causes movement of one frame relatively to a parallel frame, a flexible strip carried by the movable frame being connected to a second flexible strip carried by the fixed frame, the connecting member between the strips causing movement of the pointer spindle. A base A supports a pillar B carrying the indicating mechanism while supported on the base A is a work-carrying table C the spindle of which is screwed to engage a nut E by turning which the table may be raised and lowered without rotating. It may be clamped in adjusted position by a bolt H passing through a diametrical slot in the spindle D. The table C is detachable and specially shaped tables may be substituted therefor. The indicating mechanism is carried by a back plate J secured to a bracket movable up and down the screwed pillar B to which it may be clamped. The measuring anvil L<SP>1</SP> is fitted to the lower end of a cylindrical plunger L slidable vertically on balls Q in a channel piece R fixed to the back plate J. The plunger L has a cross-head M to which are fixed springs P which exert both a horizontal pull on the plunger keeping it against the balls Q, and also a smaller vertical pull. Mounted on the back plate J is a horse-shoe frame S having stretched diametrically across it a spring strip T. Disposed adjacent this frame is an annular frame U having a similar spring strip V parallel to and aligned with the strip T. The strips are connected at their centres by a member t<SP>1</SP> comprising three small plates bolted together. Interposed between the frames are balls W located in V- grooves parallel to the plunger L cut in the adjacent faces of the frames, three in the frame U and two in the frame S the third groove in the frame U being opposite a flat on the frame S. The frame U is constrained to move upwards and is kept against the balls by springs X attached to rods X<SP>1</SP> lying parallel in eight grooves in the outer faces of the frames. A small pin U<SP>2</SP> on the frame U engages under a plate N carried by the plunger L. Fixed to the member t<SP>1</SP> are a pair of divergent arms Y to the ends of which are secured metallic ribbons Y<SP>1</SP> passed in opposite directions around and clamped to a shaft Z or to a collar or pulley thereon. A pointer Z<SP>1</SP> is mounted on the shaft, the end of the pointer being bent to enter an arcuate slot in a scale plate Z<SP>3</SP> supported on a bearing coaxial with the shaft Z. The scale marks are not radial and by observing the point at which the pointer cuts a scale mark a finer reading is obtained. The scale plate is adjustable by a screw Z<SP>8</SP> passed through a fixed bracket Z<SP>7</SP> and abutting against an abutment piece Z<SP>8</SP> on the scale plate which is held against the screw by a spring Z9. The plunger may be lifted by a small hand lever l<SP>2</SP> which moves a lever l<SP>3</SP> to engage under a stop l<SP>4</SP> on the plunger against a restoring spring. The lift is limited by a lever l<SP>7</SP> engaging a stop l<SP>6</SP> which may be withdrawn. A conducting disc Z<SP>11</SP> on the shaft Z rotates adjacent the poles of a damping magnet Z<SP>10</SP>. Wire fingers may be adjusted over the scale to indicate tolerance limits. The arms Y and ribbons Y' may be dispensed with and a mirror mounted centrally on one of the plates t<SP>1</SP> to project an incident light beam on to a screen. Specification 134,484, [Class 106 (ii)], is referred to.