GB278749A - Improvements in speed measuring apparatus - Google Patents

Abstract

278,749. Mombur, G. Oct. 7, 1926, [Convention date]. Impulse speed-indicators. - A speedometer of the balance wheel type receives its impulses from an armature electromagnetically oscillated at the frequency to be measured and in constant gear with the balance wheel, or itself forming the balance wheel. In the form shown in Fig. 1, the electromagnets 10 rock an armature 8 geared through a rack and pinion with a spring-controlled balance-wheel 1 arcuately slotted at 12 to engage the arm 14 rigid with the pointer. The balancewheel spindle has a toothed wheel to mesh with a pinion 15 carried by a lever 17 influenced by opposing slightly unequal springs and rocked at each energization by the bridge bar 20 gapped at 21 to attract the armature. 19 fast with the lever 17. The pinion is provided with a threearmed block 22 justified by a blade spring and is limited in rotation by engagement of one of its arms with a fixed pin 23 so as to restrict the movement given to the balance wheel at each impulse to a constant amount. To vary the duration of each impulse, the primary shaft may be provided with a contact drum having an insulating portion of increasing width on which bears an adjustable contact piece. The pointer may be damped by a pair of bars 26, 27, Fig. 3, magnetized at each impulse and engaging a disc 28 fast on the pointer spindle.