Patent GB-587732-A (GB)
Title: Improvements in apparatus for measuring deflections under load
IPC: G01B3/24
Filed: 1945-01-11
Abstract: 587,732. Testing anti-vibration mounting devices &c. WELLS & CO., Ltd., A., and WELLS, A. W. J. Jan. 11, 1945, Nos. 946 and 2125. [Class 106 (ii)] Apparatus for measuring the compression or extension under load of an anti-vibration mounting device, spring, &c. comprises a feeler arm 35 lightly biassed to contact the specimen 28, a deflation indicator comprising a scale 14 and pointer 38, one of which (e.g. the pointer) is linked to the feeler arm to move. therewith, means for adjusting the other (e.g. the scale) to set the pointer initially at zero on the 'scale, a normally inoperative load-applying member 39 having release means 44 which applies a known load through the feeler arm to the specimen. The pointer may be set at zero, either manually or automatically. The'frame comprises a box-like casing 10 on a base 11. The scale 14 is arcuate and visible through a window 13, and is carried on a bar 17 pivoted 'at 18, a cranked extension 19 on the bar carrying a handle 20 which projects through a slot in the casing 10 and has a friction locking- device to maintain the scale in adjusted position. A table 26 slidable horizontally on a guide 25 on the base 11 has a mounting 27 thereon for the specimen 28 which may be an anti-vibration mounting device of the kind described in Specification 571,026, [Group XXXII]. The table 26 is normally biassed towards the box 10 by a spring 29, but can be moved away to enable a specimen to be placed thereon by a foot-pedal linkage including a rod 30, bell-crank lever 31, and link 32. The upper end of the specimen 28 positions a roller 34 on the feeler arm 35 which is pivoted at 36 and connected to a lever 37 pivoted to the pointer 38. The pointer is pivoted about a pivot coaxial with the pivot 18. The arrangement gives a light downward bias to the roller 34, and the movements of the latter are magnified by the pointer 38. The member 39 slides vertically in ball bearings 40, 41, has a platform carrying a weight 43, and a fixed collar 84 engaged by a lug 44 which is carried by a handle 45, Fig. 6. The handle 45, which projects beyond the casing 10 and is pivoted thereto, is tubular and provided with thumboperated latching-means 47 adapted normally to engage a fixed stop 48 on the casing to hold the member 39 away from the roller 34. The scale 14 is provided with marks indicating maximum and minimum'deflections. By substituting a vertical bracket for the mounting 27, the specimen can be mounted and tested for radial deflection. For applying tension to a' coil spring to be tested, one end of the spring is engaged by a hook on the base 11 and the other end by a hook on the feeler arm 35, the load being applied to the arm 35 to the right of the pivot 36. In modifications, a mechanical or an electromagnetic device automatically ensures initial zero-setting of the pointer 38. The mechanical device comprises a scale arm 117, Fig. 6, weighted to move down with the pointer 38 and a projection on the scale arm resting on the pointer so that the scale will move up with the, pointer when the specimen is introduced beneath the roller of the feeler arm, the pointer being at zero during such movements. An extension 56 of the scale arm is adapted to be clamped against the inner wall of the casing 10 by a pin 55 to hold the scale in adjusted position, on operation of the handle 45 to allow the load bar 39 to descend, the pin 55 being returned to inoperative position when the handle 45 is returned to latched position. The pin 55 is urged towards the extension 56 by a spring 60, but is controlled by an extension 61 of the handle 45. The electromagnetic device comprises one electromagnet arranged on the scale arm or the pointer to clamp the two together with the pointer at zero during the introduction of the specimen, and a second fixed electromagnet, normally de-energized, in wiping contact with the scale arm, the thumb-latch on the handle 45 being arranged to de-energize the first and energize the second electromagnet when the load bar 39 is released, whereby the pointer moves and the scale is fixed.