IMPROVEMENTS IN CHANGING OR REVERSING MOTION
Year: 1859

page_text: PROVISIONAL SPECIFICATION left by Henry Lea at the Office of the
Commissioners of. Patents, with his Petition, on the 12th February
1859.
I, HENRY LEA, of Birmingham, in the County of Warwick, Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
CHANGING OR REVERSING MOTION," to be as follows, that is to say:-—
My Invention is applicable to any machine in which a ratchet wheel and
pall is used for the purpose of advancing a slide or table step by step along its
bed, and is designed to prevent any accident in quick moving machines from
the table being drawn up by its screw against the end of the bed, thereby
causing certain breakage of some part of the machinery. In the Drawing
Fig. 1 is a side elevation, and Fig. 2 an end view of a' slide and screw with
the motion attached. (a) is the slide, (b) its bed bolted to the carriage (c) of
the machine; the screw (d) is driven in the ordinary manner by a rod (e)
and bell crank lever (f), carrying a pall (9); this gears into the ratchet
wheel (h), which is removed in Fig. 2 to shew more plainly the levers, &c.,
behind it is a wrought-iron bar of the form shewn, and capable of
.being moved longitudinally only on the face of the carriage (c); it is pre-
vented from any side movement by being fitted into a groove planed in the
bottom of the bed. (b); the ends of the bar are returned upwards, and
provided with set screws K, L, placed at such an elevation that the springs
M, which are screwed to the slide (a), will come in contact with them
alternately as the slide moves backwards and forwards. The bar is
continued towards N, N, two guards formed on top and bottom of it, and the
metal between the, two is cut out, so as to form a square hole, as shewn by

page_text: the dotted lines; through this hole passes the slotted rod O, forked at the
lower end, and carried there by a short lever P, which again is mounted on a
stud in the bracket Q; the top end of O is single, and hung by a pin to the
short lever end of a quadrant R; this is made with a boss fitting loosely over
the boss of the bell-crank lever (f), which is also loose on the screw (d), the
wheel (1) alone being fast on. A continuance of the pall (9) passes as a
round pin through one arm of the bell-crank lever (f), and on it is made fast
by a nut and washer the small toothed pinion S, gearing into the aforesaid
quadrant R. In the slot of the rod O are placed two round studs or pegs
T, U, held fast by nuts and washers; (w) is the usual spring box and spring
keeping the pall (9) up to its work.
The action is as follows:-Motion being given from the driving shaft of the
machine to the rod (e), it causes the lever (f) to vibrate on its centre, carrying
with it the pall and quadrant, and consequently giving a vertical motion to the
rod O; the quadrant end R and lever P being of equal lengths, the centre
part of O will describe a straight line, at the same time the pall (9) carries
forward at every return stroke the wheel (h) and screw (d), thus advancing
the slide (a) along its bed until one of the springs M comes into contact with
a set screw (say K), and causes the bar I to be moved a distance equal to the
length of the last stroke of the slide; in this position the Drawing shows it.
Now the stop U, which had previously been working freely in the square hole
of I, is caught as it rises by the solid metal forming the end of the bar I,
thereby being prevented from rising further, and thus holding the toothed
quadrant R stationary while the bell crank (f) continues its stroke, thus
compelling the pinion S to roll over the quadrant R, and turning the pall (9)
back to the under side of (h); this reverses the direction in which the screw
(d) revolved, and the slide a is carried back towards the set screw L, when
the bar I is moved and intercepts the stop T in descending, thus holding the
quadrant R again stationary, while the pinion S and pall 9 are turned over to
their original places. The guards N, N, are to prevent any accident from the
bottom stop catching on the top of the bar, or vice versa. The springs M are
moving while either
necessary to prevent any undue strain, should the bar be
stop is inside the hole in the bar, and lastly the slot in the rod O allows for
any variation in the stroke of the rod e.