Patent ID: 8413348
Filing Date: 2013-04-09
Classification: G01B

Abstract:
1. A displacement measuring instrument comprising: a body; a stationary sleeve fixed to the body; an axially movable spindle having a male thread portion screwed to the stationary sleeve; a thimble rotatably fitted onto an outer circumference of the stationary sleeve; an operation sleeve fitted over a range from an outer circumference of the thimble to an outer end of the spindle and being rotatable relative to the thimble; and a constant pressure mechanism interposed between the operation sleeve and the spindle, the constant pressure mechanism transmitting a rotation of the operation sleeve to the spindle and allowing a free rotation of the operation sleeve relative to the spindle when a predetermined or more load is applied to the spindle, wherein the constant pressure mechanism comprises: a rotary driving element rotatable together with the operation sleeve; a rotary driven element coupled to the thimble while coupled to the rotary driving element in such a manner as to be rotatable together with the rotary driving element but not to be rotatable when a predetermined or more load is applied to the spindle; and a rotation transmitting mechanism transmitting a rotation of the rotary driven element to the spindle, a male thread portion having the same pitch as a pitch of the male thread portion of the spindle is formed on the outer circumference of the stationary sleeve, and a female thread portion is formed on an inner circumference of the thimble, the female thread portion screwed to the male thread portion of the stationary sleeve.