Patent GB-258015-A (GB)
Title: Improvements in or relating to apparatus for measuring the twist imparted to a shaftunder load
Filed: 1925-06-13
Abstract: 258,015. British Launderers' Research Association, Parker, R. G., Jackman, D. N., and Bailey, F. J. June 13, 1925. D y n a m ometers, rotary - transmission.-Apparatus for indicating or recording the twist of a shaft comprises two supports clamped to the shaft at points between which the twist is to be measured, a. tilting mirror carried by one support, means carried on the other support for tilting the mirror, a source of light carried by the shaft, and means clamped to the shaft to receive the beam of light reflected from the mirror. A sleeve 1 divided longitudinally embraces the shaft 2 the parts being mounted on blocks 3 having gripping edges 4 and being secured together by bolts 5. The opposite end of the sleeve carries an arm 6 in proximity to a second support 7 carried on blocks 8. Secured to the block 8 and arm 7 is a bush 11 which forms a bearing for the adjacent end of the sleeve 1 between which and the bush are ball races 12. On the arm 6 is a spindle 13 carrying a support for a mirror 14. The bearings for the spindle are carried by a plate 30 which may be adjusted and clamped by a screw 31. The spindle 13 is grooved to receive a catch on a light spring 19 carried on a stout pin 20 projecting from the arm 7 through a hole in the arm 6. The pin 20 can be adjusted lengthways in a sleeve 21 by a screw 22 and return spring and the sleeve is mounted in a slide 24 which may be adjusted by a screw 26 and return springs. A clamping screw 28 is also provided. Mounted on the shaft by blocks 32, 33 is a support 34 for a film camera. A beam of light from a source mounted on the camera is directed on to the mirror which reflects it back through a slit and thence on to a film carried on rollers 37. Any other means such as a long cylindrical lens of small diameter may be used for admitting light to the camera. The light source in the present instance is an electric bulb 38 carried in a tube 35 having a lens 40. The film mechanism is actuated by gearing 42 driven by worm gears 43, 44 of which the latter comprises a ring loosely mounted on the camera support and is secured to a brake drum 45 loose on the support. This is embraced by a band 46 which carries an adjustable bracket adapted to be clamped to a fixed support. The two sections of the brake can be clamped on the drum by a Bowden wire. When the ring 44 is braked the wheel drives the gearing 42 causing the rollers carrying the film to move. In order to enable readings to be taken by daylight, a light-box 54 may be provided and a fixed mirror to give a zero line. The moving parts are balanced. In a modification, the light is projected through a screen and lens on to a selenium cell in circuit with an electrical instrument. The screen varies in opacity from end to end. Slip rings or bushes are provided for taking the current to the revolving instrument. Due to the clearance between the bush 11 and the sleeve 1 the mirror receives a slight oscillation at each revolution and this causes a zigzag to be traced by the light spot within a narrow band which shifts sideways as a whole on change of twist. This zigzag thus records the number of revolutions.