The first Big Ben movement patent shows 2 types of repeat lever. Inventor George Kern changed the repeat lever several times, until the familiar type evolved.
Repeat Lever A1:
The repeat lever rotates on a steel stud fastened to the front plate. The brass wire tension spring wraps around the stud. One end of the tension spring bears on a PROJECTION on the lever, the other end bears on a brass post riveted to the front plate. The repeat lever has an oblong opening around a brass post in the front plate that limits its travel. Shown in drawings 1, 5, 6 and 7 of patent 904333.
Repeat Lever A2:
The repeat lever rotates on a steel stud fastened to the front plate. The brass wire tension spring wraps around the stud. One end of the tension spring bears on a projection on a STEEL POST riveted on the repeat lever near the center arbor, the other end bears on a brass post riveted to the front plate. The repeat lever has an oblong opening around a brass post in the front plate that limits its travel. Shown in drawing 8 of patent 904333.
Repeat Lever B1:
This type of repeat lever has ITS OWN ARBOR AND PIVOTS, and is pivoted at the normal location, with a flat steel tension spring attached to the front plate. The lever is located between the third wheel and the repeat cam, with a pin projecting toward the front plate that engages with the repeat cam. The lever has a right angle shape about its arbor, and an approximately 45 degree angle bend about halfway between the pivot and the end which engages the alarm trip spring. The repeat cam is closer to the front plate than on later types.
A round STEEL pin with flat on the backside engages the repeat cam.
Repeat Lever B2:
This type of repeat lever has ITS OWN ARBOR AND PIVOTS, and is pivoted at the normal location, with a flat steel tension spring attached to the front plate. The lever is located between the third wheel and the repeat cam, with a pin projecting toward the front plate that engages with the repeat cam. The lever has a right angle shape about its arbor, and an approximately 45 degree angle bend about halfway between the pivot and the end which engages the alarm trip spring. The repeat cam is closer to the front plate than on later types.
A round BRASS pin engages the repeat cam.
Repeat Lever C:
Repeat lever pivoted on center arbor. FIRST TO HAVE TRIANGULAR LIFTER engaging the clickwheel. FIRST with triangular catch attached to hammer verge tail. Both plates have small rectangular hole at edge near alarm train second wheel pivot hole. Small brass punching attached to front plate at this point to serve as a guide and stop.
Repeat Lever D:
Repeat lever of the usual type: flat tension spring, repeat lever located between tension spring and front plate, repeat lever has brass triangular lifter the engages the repeat cam, STEEL OR BRASS triangular catch on hammer verge tail.
Repeat Lever E:
Modified for later clocks having the larger diameter, stronger alarm second wheel arbor.
