US PATENT SUBCLASS 400 / 563
.~.~ Including plural detents selectively engageable with ratchet wheel

Current as of: June, 1999
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400 /   HD   TYPEWRITING MACHINES

545  DF  FOR LINE-SPACING BY INCREMENTAL ROTATION OF PLATEN {15}
555  DF  .~ By irregular increments of platen rotation (e.g., for adjustment of platen relative to its actuator, etc.) {6}
563.~.~ Including plural detents selectively engageable with ratchet wheel

DEFINITION

Classification: 400/563

Including plural detents selectively engageable with ratchet wheel:

(under subclass 555) Subject matter wherein said first mechanism includes a first ratchet* in the form of a disc or wheel having teeth protruding from a peripheral edge thereof and notches between the teeth, and also includes a first arm having a protrusion that meshes with one of the notches in the ratchet disc to restrain rotation of the disc, and wherein said second mechanism includes a second arm having a protrusion that meshes either with notches in the first ratchet disc or with notches in a second ratchet disc, and wherein the first arm is used for normal incremental rotation of the platen* or the second arm is used for other than normal rotation of the platen.

(1) Note. In the device defined above, if one ratchet wheel is used with two detents that are alternately engaged with the ratchet wheel, the space between the detents in the circumferential dimension of the ratchet wheel is such as to provide irregular increments of detented ratchet-wheel position. If two ratchet wheels are used with two detents, one of the ratchet wheels is provided with teeth having a circumferential spacing different from the other, and one detent is used with one of the ratchet wheels for normal incremental rotation, and the other detent is used with the other ratchet wheel for other than normal incremental rotation.