GB346543A - Improvements in or relating to clocks - Google Patents

Abstract

346,543. Clocks. WHIDBOURNE, H., Royal Aircraft Establishment, South Farnborough, Hampshire. March 12, 1930, No. 8054. [Class 139.] Escapements ; transmitters. - A pendulum e s - capement mechanism comprises a pivoted gravity arm (impulse member) 25 for acting intermittently on a pin 24 on the pendulum 21, a second pivoted arm 30 movable with arm 25 to lock and unlock the driving mechanism alternately, and a third pivoted arm 33, acted upon by the driving mechanism for moving the second arm 30 in and out of locking position. The pivoted pin 24 is in a recess 23. in the pendulum which is supported on the usual strip 22. A weight is used for driving scape member 28 which has limbs 29 and lateral pins 31. The first and third arms 25, 33 are rigid with shaft 26 and second arm 30 is loose on this shaft but is. biased counterclockwise, Fig. 5, by a spring, a projection 39 on this arm meeting a stop on the back of arm 33. A block 44 on arm 25 carries a blade 43 with a contact 41 which coacts with a fixed contact 42. Pivoted to the end of third arm 33 is link 32 having a collar 34 which coacts with pins 31. A lug 37 on arm 33 limits the movement of link 32 in one direction and a fixed pin 38 in the other direction. With the pendulum central, 27 rests on pin 24, contacts 41, 42 are closed, and second arm 30 holds a limb 29. As the pendulum swings to one side the three arms 25, 30, 33 fall and the part 27 gives the pendulum an impulse through roller 24, lever 30 releases the limb 29 and'the scape member 28 rotates, until a pin 31 raises link 32 and arm 33. This raises arm 30 to engage the next limb 29. Arm 25 is not raised sufficiently to close contacts 41, 42, however, until on the return movement of the pendulum the roller 24 lifts the arm 25 to its highest position to close contacts 41, 42. This action of roller 24 also raises arm 33 and link 32, so that the latter is moved off its pin 31, and the three arms 25, 30, 33 drop to release the scape member once more. Roller 24 and part 27 may be interchanged: The impulses given when contacts 41, 42 close may, for example, be used for controlling speed-regulating devices, such as described in Specification 334,214, [Class 57, Governors & c.], or for. controlling secondary clocks. A lost-motion device between the first and second .arms is described, in a modification, to ensure that the first arm,. 25, completes its impulse-giving movement before the second arm releases the scape member. Specification 233,828, [Class 139, Watches &c.], also is referred to.