GB1116400A - Measuring apparatus - Google Patents

Abstract

1,116,400. Testing properties of materials. DUNLOP CO. Ltd. Oct.29, 1965 [Nov. 6, 1964], No.45805/65. Heading G1S. Measuring apparatus comprises two rotary measuring devices 4, 5 for measuring the variation in length of a sample of material 1 and locatable in positions spaced apart in the direction of variation in length to be measured, a differential gear assembly 12 having two input elements 10, 17 each driven by one of the measuring devices, and indicator means 25, 32 driven by an output element 20 of the differential gear assembly. In the embodiment illustrated the specimen is clamped between two clamps 2, 3 the load being applied to clamp 3. The specimen is held in contact with the measuring rollers 4, 5 by further rollers 6, 7, measuring roller 4 being mounted on axle 10 which ends in a bevel gear wheel 11 forming part of the differential gear assembly. The lower roller 5 is mounted on an axle 13 connected through a cross belt 15 to an oppositely rotating axle 17 which also ends in a bevel gear 18 forming another part of the gear assembly. Four idler bevel gear-wheels 21 mesh with the gears 11, 18. When the load is applied to the specimen, the rollers 4, 5 rotate an amount dependent on the extension of the specimen from the corresponding roller to the clamp 2. As a result of this rotation the gears 11, 18 will rotate in opposite directions and different amounts, causing the differential gear casing 19 and ring gear 20 to rotate. The difference in the angle rotated is directly proportional to the modulus of elasticity of the specimen and hence pointers 25, 32 can be calibrated to give a direct reading. The apparatus may also be used to measure contraction.