Internal micrometer using probed moved by racks - has radially floating gears and endless screw to drive racks

摘要

A micrometer for internal measurements has three equally spaced probes which move radially with respect to the micrometer axis. A micrometer head (1) contains three measuring probes (2) which slide in guide channels (3). Each probe has a longitudinal rack (7) which engages with a toothed wheel (17) which is able to float radially and is in contact with an endless screw (11). Radial movement is limited by housing (18) but it cannot disengage completely from the rack or screw thread. A sleeve (20) houses a shaft (12) which turns the endless screw. On the sleeve is screwed a tubular body (21) comprising an analogue indicator with micrometer screw and which when rotated determines movement of the probes.