GB184289A - Improvements in apparatus for measuring speeds - Google Patents

Abstract

184,289. Seguin, A. May 18, 1921. Differential and momentum speed indicators; transmission mechanism.- In apparatus of the type described in Specification 155,791, the gear-wheel 4 driven according to the speed to be measured carries a spring-controlled lever 11 pivoted at 12 and adapted to pick up and, at a fixed point, to release a striker 5 loosely mounted coaxially with the balance-wheel 6 and arranged to operate it by abutment against a pin 19. The balance wheel, controlled by a spring 7, is frictionally mounted upon a sleeve g<1> which is attached to the shaft g and carries a disc La provided with the pin 19. The lever 11 has a stud 13 to engage the striker head 2' and also a pin z to bear on a fixed cam formed with a nose 20. In operation, the lever engages the striker and drags it around together with the balance-wheel until the nose 20 is encountered by the pin z. This deflects the lever 11 outwards so that it releases the striker, which thereupon swings back with the balance wheel until again picked up by the lever 11. The friction-held pointer 9 has an arm 10 provided with a pin 8 which is positioned bv the striker or by the hooked end v of the lever, depending upon the sign of the speed variation until the striker and lever meet, whereupon the pin 13 rides up the inclined edge 1 of the striker, and engages with the radial edge 2 and thus releases the pointer pin 8. The spring r normally bears with its extremity upon the lever 11, but when the latter is moved outwardly by the cam nose 20 the point of bearing shifts to the pin z, thus temporarily increasing the effect of the spring. To prevent damage to the apparatus by reversal of the drive to the wheel 4, the driving-pinion e is loose on its shaft and is driven in one direction only through a pair of pawls 25 constituted by spring tongues of a cut-away plate 23 secured to the shaft. In a modification, shown in Fig. 9, the lever 11 is controlled as before by a cam, which then has the form of a groove A<1>, but the pointer extension 8 is engaged by the lever through the medium of a pin V mounted on a spring t. The return of the balance-wheel effects by means of a pin 19 the radial displacement of this spring and consequent release of the pointer. The pointer may be dispensed with and the striker coloured or rendered luminous so that it becomes visible at the moment of its collision with the pin 13. The striker may be driven at a reduced speed from the balance-wheel instead of rotating with it.