GB818407A - Improvements in or relating to dial gauges - Google Patents

Abstract

818,407. Dial gauges. INSTRUMENTAKTIEBOLAGET METRON. Aug. 31, 1956 [Aug. 31, 1955], No. 26717/56. Class 106 (2). A dial gauge comprises a feeler stem 14, a transmission member 24 movable relative to the stem 14 and urged away from the feeler tip 50 by a spring 48, the member 24 transmitting through a transmission system 26, 30, 32 movement of the stem 14 to a pointer 20, and the stem 14 carrying a movable abutment 54 against which the member 24 is pressed by the spring 48; means being provided to move the abutment along the stem 14, without rotating the latter, to set the pointer to zero. A pin 44 passes through slots 40 in the stem 14, and into a recess 46 in the casing 10 to limit movement of the rod 14, and is fixed in the transmission member 24. It is held between a screw 54 and a ball 56 by the spring 48, the screw 54 being used to adjust the initial position of the pointer 20. A band 26 is attached to the transmission member 24 and drives a band drum 28 to which is attached a toothed segment 30 driving a pinion 32 carrying the pointer 20. Fig. 5 shows a restoring spring 60, which is attached at 62 to the casing 10 and at 66 to a toothed segment 68, turnable relative to the segment 30. This eliminates tooth play between the gears and provides an approximately constant restoring force. An alternative method of achieving this by means of two springs and only one toothed segment is also described. The spring 60 may also be arranged with one or more loops in it to provide a more constant restoring force. To allow for slight inaccuracies in the diameter of the drum 28, the ends 72, 92 of the band 26 are provided with slots 84, 86 and 94, Fig. 7, so that the band may be effectively lengthened and one end adjusted in a direction transverse to its length. Alternative methods of connecting the band 26 to the segment 30 are shown and also a method of increasing the transmission ratio, Fig. 8, using two bands acting on a segment 96 with different sized drums between the transmission member 24 and the toothed segment 30. The spring 48 acts as a shock absorber, and the inability of the stem 14 to turn, due to the pin 44 in the recess 46, makes this instrument suitable for use when the measuring feeler is chisel-shaped or is in the form of a laterally protruding arm for internal measurements. The segment 68 may also carry a pointer 22 to indicate the number of revolutions of the main pointer 20.