Patent GB-167911-A (GB)
Title: Improved device for examining or measuring the accuracy of the teeth of pinions, gear wheels, gear cutting hobs and the like
IPC: G01B5/20
Filed: 1920-06-09
Abstract: 167,911. Mensforth, H., Cowell, F. A., and Metropolitan-Vickers Electrical Co., Ltd. June 9, 1920. Surface and outline gauges. -A device for examining the accuracy of the teeth of a helical pinion, gear-wheel or hob comprises means for taking measurements of the teeth at determined distances along lines parallel with the axis of the pinion, and means for accurately rotating the pinion through determined angles. The gear-wheel 1 having helical teeth 2 is mounted by the shaft portions 3 on the roller bearings of brackets 4, 5 which are adjustable along a groove 6 in a base-plate 7, and may be clamped in the adjusted position. The ends of the pinion abut against ball stops on brackets 12, 13, of which the stop on the bracket 13 is adjustable. An arbor 25 is mounted on V-blocks 22, 23, which slide in transverse grooves 24 in the bed-plate and are adjusted so that the axis of the arbor is parallel with that of the pinion 1. The arbor is movable longitudinally and is positioned by means of " longitudinal-pitch " gauges 26 carried on V-blocks 27 on a support 31 adjustable in transverse key-ways 32, the pitch gauge 26 engaging between a fixed stop and the end of the arbor in a manner similar to the pitch gauges described in Specification 162,457. The arbor 25 carries a rest or saddle 38 which may be clamped to it and which is provided with an extension 47 adapted to abut against a fixed bar 42 parallel tothe axis of the pinion. The saddle 38 carries a two-armed lever 40 pivoted on a horizontal axis, the short arm of which is adapted to engage the teeth of the pinion while the long arm engages the plunger of a dial or like gauge 44. Secured to the right-hand shaft portion 3 of the pinion is a drum M which is bolted to a hub 51 adapted to be forced on to a split sleeve 52 and secured by a clamping-nut. The periphery of the drum is formed with a groove and a plain part. A cord attached to the drum passes around the groove and guide pulleys to a balance weight, while also attached to the plain part of the drum is a steel tape 65 which passes over a table 59 at rightangles to the axis of the pinion 3 and around guide pulleys to a similar balance weight. Mounted above the table 59 is a slide 67a formed with a groove 68 in which slides a shoe 70, which may be clamped at 71a to the slide. The steel tape 65 passes between a plate 73 and the shoe 70, and may be clamped to it by a thumb-screw 75. A second arbor 76 is mounted in V-blocks 77 secured to the table 59, and is positioned by " circular-pitch " gauges 78 inserted between the .end of the arbor and a fixed stop 80, and carried on V-blocks. A saddle 83 may be clamped to the arbor 76 and carries a two-armed lever, one arm of which engages the plunger of a dial or like gauge 90, while the other arm engages the end of the shoe 70. An arm 91 having a split boss 92 is capable of being clamped to the boss 51 of the drum, and carries at the other end an adjusting-screw 97 abutting against the upper end of a pillar 98 secured to the bed plate. To test the accuracy of the teeth 2, one of the longitudinal pitch gauges, preferably the shortest, is inserted at 26, and the angular position of the gear adjusted by means of the lever 91 and fineadjustment screw 97 until the dial gauge 44 reads zero, the end 41 of the lever being then in contact with a tooth, on the pitch circle diameter, and the arm 47 in engagement with the bar 48. 'The shoe 70 is then adjusted, and clamped so that, with one of the circular pitch gauges inserted, the dial gauge 90 also reads zero. A series of " longitudinal pitch " readings are then taken by inserting the various gauges 26 and observing the readings of the dial gauge 44. In order to take another set of readings, the arm 91 is unclamped, raised, clamped again, and moved downwards. The shoe 70 slides in the groove 68. The appropriate circular pitch gauge 78 is inserted and the screw 97 adjusted until the dial gauge 90 again indicates zero. Another set of " longitudinal pitch " readings may then be taken as above. The shoe 70 may be moved periodically relative to the tape to reduce the number of circular pitch gauges necessary. The device may be used to test hobs in the manner described in Specification 162,457, by pivoting the lever 40 about a vertical pivot and using additional " lead " gauges as set out in that Specification.