US1480346A - Escapement mechanism - Google Patents

Description

Jan. 8 1924.

cl H. BRIGDEN ESCAPEMENT MECHANISM Filed June' 8, 1922 $0 /7 IljJllllllllll II Patented Jan. 8, 1924.

UNITED STATES CHARLES H. BRIGDEN, 0F WALTHAM, MASSACHUSETTS.

ESCAPEMENT MECHANISM.

Application filed June 8,

T 0 all whom it may concern-.-

Be it known that 1, CHARLES H. BRIGDEN, a citizen of the United States, residing at WValtham, in the county of Middlesex and State of Massachusetts, have invented new and useful Improvements in Escapement Mechanism, of which the following is a specification.

This invention relates to escapement mechanisms more particularly designed for tower clocks and primarily seeks to provide such a mechanism which is unaffected by variations in the propelling force, or in the resistance encountered. Such variations are often caused in practice by loads of snow and ice on the clock hands tending to retard the movements of the hands to the left of the vertical median line of the clock and tending to accelerate their movement at the right of the median line. It also provides a construction by which the usual heavy crutch is eliminated, so doing away with the friction of its bearings, substituting in place thereof a few simple comparatively light parts substantially unsubject-ed to friction bearing.

For these and other purposes this invention provides a construction wherein. the force for moving the pendulum, or other controlling member, is imparted thereto by a spring which is energized to a uniform amount for each actuation of the pendulum regardless of variations in motor or resisting forces.

For a more complete understanding of this invention, together with further objects and advantageous details and combinations of parts, reference may be had to the accompanying drawings in which Figure 1 is an end elevation of the upper portion of a tower clock movement constructed according to this invention, the pendulum being swung to one side.

Figure 2 is a side elevation of the same portion of the mechanism.

Figure 3 is a perspective partly broken away of the spring clutch and pendulum suspension.

Figure 1 is a fragmentary view similar to a portion of Figure 1, but showing the pendulum swung to the opposite side of the vertical.

Figure 5 is a diagrammatic view showing the principle of operation of this invention.

Referring to these drawings at 1 is shown an arbor carrying an escape wheel 2, this 1922. Serial No. 566,715.

arbor being journaled in a pair of side frames 3. This arbor is connected through a pinion 4 and gear 5 with any suitable source of motive power not shown herein. Cooperating with the escape wheel 2 is a pallet 6 fixed to a rock shaft 7. This rock shaft passes through an opening 8 in the forward frame member 3 and has reduced extremities which are journaled in a pair of brackets 9 and 10 bolted or otherwise fixed to the under side of a top frame member 11.

The rock shaft 7 is journaled with capability of a slight endwise motion for the purpose of providing against cramping of the shaft due to any warping of the frames 3 or distortion due to temperature changes or other causes. The forward end of the rock shaft 7 has fixed thereto a block member 14: which is forked at its outer end to form a pair of arms 15. Depending between the pair of arms 15 is one of a pair of spaced arms 16 of a pendulum support 17. These arms 16 are slotted and within the slots are made fast the upper ends of a pair of leaf springs 18 which form the pivotal axis of a pendulum, the upper member of which comprises a hanger 19 having spaced arms 20 positioned opposite the arms 16 which are slotted to receive the lower ends of the springs 18 which are made fast therein.

The member 19, as shown, is provided with a transverse pin 21 at its lower end over which the usual hook support of the pendulum rod (not shown) may be engaged. Between the arms 16 of the pendulum support so as to be straddled thereby and also fixed between the arms 15 of the block or member 14 is the upper member 22 of a spring crutch. This crutch member, as shown in Figures 3 and 5, is provided at its lower end with a wide slot 23 and upwardly therefrom a narrower slot 24. Within the narrower slot is fixed the upper end of a pendulum impulse leaf spring 25 which is free to bend within the wide slot 23. The lower end of this spring is fixed in the lower crutch block 26, the lower end of which is formed with a groove 27 slidably engaging a lug 28 mounted for transverse adjustment by means of a screw 29 on the pendulum element 20. This construction insures against relative lateral movement of the block 26 and the pendulum element 20, but permits axial movement of thepallet rock shaft 7, the block rocking with the pendulum.

The spring 25, which has been above re ferred to as the impulse spring, is designed to be flexed by rocking of the pallet shaft to impart swinging impulses to the pendulum, it as will later appear, also designed to be flexed by movement of the pendulum to impart a further rocking motion to the pallet shaft to release the escape wheel.

In operation it is quite important that the center of oscillation of the pallet shaft, which is its axis should be directly in line *ith the pivotal center of the pendulum. F or this purpose adjustment of the support 17 has been provided both vertically and laterally. The vertical adjustment is provided by means of a set screw 30 threaded through the upper end of the support 17 and hearing at its low -r end on a transverse pin 31 which is seated in grooves in the upper face of the frame member 11 through a slot in which the member 1? depends. Lateral adjustment is effected by means of a pair of set screws 32 which pass through opposite sides of the slotted portion of the frame member 11 and bear against opposite faces of the member 17. The end of the slot in the member 11 is normally closed by a cover plate 33. 7

ln order to impart rocking motion to the pallet shaft 7 to actuate the pendulum the pallet; (S is provided with a pair of pallet teeth 40, each tooth having an inclined face ll adapted to be engaged by the teeth of the escape wheel in such a manner as to wedge the corresponding tooth 40 outwardly to impart a rocking movement to the pallet. In order to prevent the escape Wheel from riding past the teeth l one side of each tooth is provided with a rest nib 42 against which the escape tooth impinges after it has ridden across the inclined face 41. This rest nib is at such an angle that there is no tendency for the escape tooth to swing the pallet; to disengage it therefrom.

The action of this mechanism will be understood by referring to Figures 1, 4; and 5. in Figure 1 the pallet is shown as swung so that the right hand rest nib 4:2 is in engagement with a tooth of the escape wheel. ln this position the pallet shaft has been rocked in the direction of the arrow 0 so that the upper end of the impulse spring is turned to the left, thus flexing the spring in a direc tion to impart impulse to the right to the pendulum, the pendulum being shown in this figure as being positioned somewhat to the left of the center and in Figure at Y to its extreme left hand position. In response to this flexing of the spring the pendulum starts to the right, permitting the impulse spring to straighten. Its inertia carries it beyond the straight line position and imparts a slight bend in the opposite direction to the impulse spring at the dotted line position 3/ of Figure 5. This bend in the opposite direction reacts on the pallet shaft '7 to rock the pallet shaft slightly further in the direction of the arrow a, whereupon the right hand rest nib 42 is dislodged from the end of t 1e escape tooth which immediately slips by and a tooth on the opposite side engages the inclined face d1 of the left hand pallet tooth. This wedges the pallet in the opposite direo tion to rock the pallet shaft in the direction of the arrow 7) in Figure 1 until the escape tooth is stopped by the left hand rest nib 4:2. This position of the parts shows much exaggerated by full lines in Figure 5. The impulse spring is therefore flexed in a direction to impart a left hand swing to the pendulum as this swing will straighten the impulse spring, and it remains in this position while the inertia of the pendulum is being overcome and while the pendulum is started on its reverse motion. The extreme position of the pendulum to the right hand side is shown in full lines in Figure 5 at X. The pendulum then swings to the left sufliciently to straighten the impulse spring, its inertia carries it still further to the left to the dotted line position a; and imparts a re verse fleXure to the impulse spring, rocking the pallet shaft still further in the direction of the arrow 5 sufficiently to release the left hand rest nib 42 from the escape wheel tooth. and permitting the escape wheel to move on until a tooth engages the right hand inclined face 41 whereupon the cycle of operations is repeated.

It will be seen from this description that the force applied to swing the pendulum is imparted by a flexing of the impulse spring 25, which is always flexed to the same amount regardless of the force applied to the escape wheel or to any resistance to the movement of the train of mechanism operated thereby. For this reason the force applied to the pendulum is constant and therefore its amplitude is constant. It is also seen that the usual heavy crutch with bearings is eliminated and light parts with little friction substituted therefor.

While the pivotal center of the pendulum is shown as consisting of a leaf spring 18, it is evident that any other suitable type of pivotal mounting found desirable might be employed and it is also evident th at if desired other types of control than the pendulum might be employed without departing from the spirit or scope of the invention, though the mechanism as shown is of a type which has been found quite satisfactory in practice and it is the usual practice to employ pendulums in clocks of this character.

Having thus described an embodiment of this invention it should be evident that many other changes and modifications might be made therein without departing from its spirit or scope as defined by the appended claims I claim:

1. In a mechanism of the class described, an escape wheel, a pallet shaft, a pallet carried by said shaft and cooperating with said wheel, a member having a pair of spaced arms at its outer end made fast to one end of said shaft, a block fixed between said arms adjacent their outer ends, a support having spaced. arms straddling said block between the arms of said member, a pendulum, leaf springs forming the pivotal axis of said pendulum made fast to the arms of said support, and a leaf spring fixed at one end in said block and having its opposite end in operative engagement with said pendulum and through which swinging impulses are imparted to said pendulum from said shaft.

2. In a mechanism of the class described, an escape wheel, a pallet shaft, a pallet carried by said shaft and cooperating with said wheel, a member having a pair of spaced arms at its outer end made fast to one end of said shaft, a block fixed between said arms adjacent their outer ends, a support having spaced arms straddling said block between the arms of said member, a pendulum, leaf springs forming the pivotal axis of said pendulum made fast to the arms of said support, a leaf spring fixed at one end to said block and having its opposite end in operative engagement with said pendulum and through which the swinging impulses are imparted to said pendulum from said shaft, and means to adjust said support to bring the pivotal center of said pendulum in the axis of said shaft.

3. In a mechanism of the class described, a spring crutch comprising an upper block having a slot in its lower end, a leaf spring fixed in said block above said slot and extending through said slot out of contact with the side walls thereof, a lower block to the upper end of which said lower end of said spring is made fast, and means on said lower block constructed to engage a pendulum to impart swinging motion thereto while permitting relative motion perpendicular to the plane of swing.

4. In a mechanism of the class described, a pallet shaft, a support, a pendulum pivoted to said support, a spring fixed at one end to said shaft, a block to which the opposite end of said spring is fixed, and interengaging elements on said pendulum and block through which said swinging impulses may be imparted between said shaft and pendulum but which permit a limited endwise movement of said shaft relative to said suport. p In testimony whereof I have afiixed my signature.

CHARLES H. BRIGDEN.

Images