Patent GB-539273-A (GB)
Title: Improvements in or relating to apparatus for measuring and/or indicating surface roughness
IPC: G01B7/34
Filed: 1940-02-01
Abstract: 539,273. Gauging surface roughness. KAPELLA, Ltd., and REASON, R. E. Feb. 1, 1940, No. 1980. [Class 106 (ii)] [Also in Groups XXXVIII, XXIV and XXXVII] A pick-up unit for giving indication or measurements of surface roughness comprises a framework or casing which can be adjusted relatively to the surface under investigation and which carries a pick-up head arranged to be traversed over the surface at two or more different speeds. The actual measuring apparatus to which the output of the pick-up is applied, and the pick-up itself, may be as described in Specifications 539,271, 539,272 and 539,274, [all in Group XXXVIII]. As described, three speeds are provided, the slower speeds being used for recording the wave form of the surface by a pen recorder and the fastest one for an average meter or a cathode ray oscillograph. The pick-up unit, Fig. 1, comprises a base A supporting the surface for investigation and carrying a traversely adjustable vertical pillow A2 on which a casing B5 may be adjustably positioned by rack and pinion gearing B6 and locked by a member B7. A counter-balance A4 for the casing is provided. The casing encloses the variable gearing which traverses a shaft carrying a head C2 in which is adjustably mounted an arm C1 on which the pick-up head C is mounted. Three-speed gearing, Fig. 3.-The shaft D carrying the pick-up is moved horizontally by screw gearing from rotating shaft E which, as shown, engages a half-nut D3 moving with the shaft D the screw-threads being cut with ratchet shaped section so that the shaft D is moved to the right by the gearing and may be restored by hand owing to the yielding connection D4 between the half-nut D3 and the shaft. The drive may be by a solenoid but, as shown, an electric motor F drives a pair of primary sliding pinions F3, F4 through a coupling F2. When large pinion F3 is moved to the left by selector lever H4, it drives pinion E2 secured on shaft E thereby providing the fast drive. The smaller pinion F4 drives gear-wheels F5, F6 rigid with a sleeve rotating a shaft E and wheel F6 drives a pinion F7 rigid with gear wheel G1 which also drives a second gear wheel G2 through reduction gearing G3 - G5. The gear wheels G1, G2 rotate on a sleeve mounted to slide on shaft F1. With selector lever H4 in the position shown, selector lever H3 may be operated to move gear wheel G1 or G2 into mesh with pinion E3 on shaft E thereby providing alternative slow speeds. The selector levers H3, H4 are controlled by a rotary knob H having cam slots HI, H2 engaging the upper end of the lever. Re-setting and controls.-When the shaft D has been driven to the right for a pre-determined distance an abutment D8, Fig. 7, on the shaft runs off the spring contacts J3, J4 which are maintaining the circuit of the driving motor whereby the motor is stopped. The shaft is re-set to the left by a horizontal lever J which after a small movement engages a member D7 on the shaft to restore it. During the inital movement of the lever, projection J6 thereupon engages a member J5 carried by the lower contact J4 and depresses both contacts to enable shaft abutment D8 to pass to the left above them. When the lever is restored, D8 holds the upper contact down in engagement with the lower one. The shaft D may also operate contacts, Fig. 10 (not shown), controlling the circuit of an average meter. To prevent the motor overheating on the lower gears, the driving voltage may be varied by a switch H6 operated by the selector H4.