To realize charge prevention without complicating structure.
An earth part 221 elongated to the oblique downside is provided on a lower part of a bearing case 22 pivoting a rotating shaft 3 having a contactor 4 to be pressed onto a measuring body, mounted on the front end. The earth part 221 is fitted into a hole provided in a lower wall of a case body part 1, to thereby fix and store a bearing unit 2 into the case body part 1. In this state, the under surface of the earth part 221 is exposed from the bottom surface of the case body part 1 in a configuration forming a continuous face to the bottom surface of the case body part 1, and when an operator grips a tachometer at a measuring time, the earth part 221 is brought into contact with an operator's hand and grounded through the operator. Hereby, charge protection of the tachometer from the charged measuring body is realized.
KOMATSU OSAMU
MIYASAKA MASAJI
SAITO MASATO
WATANABE TAKASHI
