Patent GB-160204-A (GB)
Title: Improvements in electric clocks
IPC: G04C3/02
Filed: 1919-10-17
Abstract: 160,204. Parsons, I. H., and Ball, A. E. J. Oct. 17, 1919. Electric clocks.-Relates to electric clocks of the kind described in Specifications 24620/04, 919/07 and 106,702, in which a pendulum is maintained in oscillation by means of a gravity lever, which is normally held up by a mechanical catch. The invention comprises two main features, which may be embodied independently, and are as follows :-(1) the energy necessary to discharge the gravity lever is stored in'a spring or weight and is derived from the current impulse which operates the clock, the release of the lever being effected while the pendulum is swinging towards zero, and (2) the gravity lever is pivoted at a point approximately coincident with the bending point of the suspension spring of the pendulum, and has a depending arm provided with a hinged member adapted to engage the pendulum only during the impulses. In the construction shown in Fig. 1, the energy required to free the gravity lever E from its support B is stored in a spring A<2>. The release occurs when a catch C is tripped by a pin M<2> and frees a lever A. This lever, under the action of the spring A<2>, pushes aside the catch B, and holds it clear of the lever E whilst this member is giving an impulse to the pendulum I. When contacts T, T<1> are closed, the armature R replaces the gravity lever on its catch and, acting through a rod D, simultaneously resets the lever A and stresses the spring A<2>. Instead of pivoting a pawl such as K<1> directly on the pendulum, a pawl may be mounted on an arm extending obliquely from the pendulum, and may be arranged so as to operate a modified form of the catch C and discharge the gravity lever on each complete swing of the pendulum. Fig. 3 shows a clock in which the energy for releasing the gravity lever E is stored in a weighted lever A, controlled by a short metronome pendulum K<8> through escapement pallets K<5>, K<6> and an anchor K<12> on the member K<8>. As the lever A, which is pivoted at A<1>, falls from the position shown, it causes the pendulum K<8> to oscillate, and when this has made a complete swing, the lever A is freed, and drops on to a catch B, releasing the impulse lever E. The members E, A are reset together by the armature R. A modification of this construction is described in which the release lever A is under the influence of a spring and is connected to a metronome pendulum through ratchet mechanism, tcothed gearing, and an anchor escapement. In this case, the release of the impulse lever occurs at longer intervals. The action upon the catch B of a member carried by the pendulum may define the exact instant of release. Fig. 5 illustrates the second main feature of the invention. The gravity lever E is pivoted at P, and its depending arm E<1> carries a hinged part Q which normally hooks over a support B. The member Q is adapted to engage with a pallet K on the pendulum, and impart an impulse, when a lever C moves the part Q from its support, and thereby frees the gravity lever. The member Q engages the pallet K without much "drop," the release and impulse being effected whilst the pendulum is swinging towards zero. In a modification of this construction, the release of the member Q is effected by an additional lever controlled by a spring in which energy is stored when the resetting-armature R operates.