no further power will be applied to the springs M9, M10. When, however, those springs have become unwound to a sufficient extent the spring N8 of the coupling M22 will be stronger than the springs of the power-storage device and will transmit, from the expansion coil, the force necessary to wind said springs as often as they become unwound; in other cases the force will be expended in simply compressing the coil spring N8 without effect upon the springs of the power-storage device.
Referring now to what I will term the force-increasing devices, which are more clearly shown in Figs. [1], [2], [4], [8] and [9].
Near each end of the upper knife-bar E, and contacting therewith at its under surface, is a support O, in the form of a flat-headed bolt (Fig. 8), the shank of said bolt passing through one end of lever O¹, which is fulcrumed at O² upon the upper surface of a cross-bar O³ securely fastened to the rear portion of the uprights C, C¹. To the front of said uprights is rigidly secured a second cross-bar O4, and at the lower portion of said uprights and rigidly secured thereto is a third cross-bar O5, against the under surface of which rests a lever O6 (Fig. 9) having its fulcrum point at O7.
As shown in [Fig. 2], there are three sets of the levers O¹, at the upper end of the expansion coils at the rear side thereof below the knife-bars E, one lever at each end of said bar and one in the middle thereof. As these levers act directly upon the under surface of the knife-bars E to raise the same I will call them knife-bar lifting-levers. There are also the same number of levers O6 at the lower end of the expansion coils below the cross-bar O5 projecting through to the forward side of the apparatus, as shown in [Fig. 1].
Rigidly secured to the cross-bar O4 is one end of a relatively heavy metallic expansion strip O8,—preferably formed of zinc—the lower end being secured to one end of the lever O6; to the opposite end of the lever O6 is secured the lower end of a similar but longer zinc strip O9, the upper end of the strip O9 being secured to the rear end of the lever O¹. As shown in [Figs. 1] and [2], there are two of these strips O8 at the front and two of the strips O9 at the rear of the apparatus.
In addition to the heavy strips O8, O9, there is provided at the front of the apparatus a heavy wide expansion sheet or strip O10, which, at its upper end, is rigidly secured to the cross-bar O4, and at its lower end to the front end of the middle one of the levers O6. A similar heavy wide expansion sheet or strip O11 is secured, at its lower end, to the rear end of the middle lever O6, and, at its upper end, to the middle one of the levers O¹.
These heavy strips O8, O9 and sheets O10, O11 are preferably formed of zinc, and are not only capable of great expansion and contraction, but will be capable by their contraction of lifting the entire weight of the knife-bars E, with the carried balance-levers and expansion strips of expansion coils, the operation thereof being as follows: