Year: 1887

page_text: Date of Application, 2nd Aug., 1887.
Specification Accepted, 13th Sept., 1887.
[Communicated from abroad by WALDO ALLEN LOUD, of Springfield, County of
Hampden, State of Massachusetts, U.S.A., Mechanical Engineer.]
I, WILLIAM PHILLIPS THOMPSON F.C.S. M.I.M.E. of the Agency for Foreign
Patent Solicitors 6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in
the County of Lancaster and 323 High Holborn, in the County of Middlesex Civil
Engineer, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement :-
This invention relates to ratchet and pawl devices, the object being to provide an
improved construction in this class of mechanism whereby the working parts are better
protected from dirt than heretofore, and great simplicity of construction and strength
are attained, and the invention consists in the peculiar construction and arrangement
of the parts of the device, all as hereinafter fully described and pointed out in the
claim.
In the drawing forming part of this specification.
Figure 1, is a perspective view of a longitudinal section of a wheel-hub, a part of a
shaft, and a pawl, illustrating ratchet and pawl devices constructed according to this
invention.
Figurè 2, is a perspective view of a portion of a gear wheel showing a central shaft
therein in transverse section, and its hub in longitudinal section with one corner partly
broken away.
Figures 3, and 4, are perspective views of the hub shown in Figures 1 and 2 divided
transversely into two parts on the line x, n, Figure 2, said Figures 3 and 4, showing
therein sections of a slotted shaft.
Figure 5, is a perspective view of the pawl.
In the drawing, 3, indicates a hub of the gear, 2, or of any other wheel to which it
may be desirable to attach ratchet and pawl connections. The said hub, together with
the wheel of which it is a part, is cast on a suitable core whereby an annular groove 4,
is formed in its inner wall about midway between the ends of the hub, and at the same
time two series of ratchet-teeth 5 are formed on the opposite sides of said annular
groove occupying the positions relative to each other shown in Figures 1 and 2.
A shaft 6, is fitted to rotate within the hub, 3, or to have the latter rotate around it,
in which shaft is formed a longitudinal groove a. The groove portion of said shaft is
adapted to rotate opposite that portion of the hub, 3, in which is the aforesaid annular
groove, 4.

page_text: A pawl, 7, consisting of a metal bar having an arm, 8, thereon at right angles thereto
and about midway between its ends, is adapted to have a free reciprocating movement
in the slot, a, in said shaft, 6, the said arm, 8, projecting from the face of the shaft and
entering the groove, 4, in the hub, 3. One side of the arm, 8, on said pawl has its
corners curved in order to facilitate its operation when said arm strikes the curved
sides of the said teeth, 5, on the sides of the annular groove, 4. Figure 1, shows the
operative position of the curved side of said arm, 8, relative to the curved sides of the
teeth 5. The parts of the ratchet and pawl mechanism herein described are assembled
together in operative position by placing the pawl, 7, within the hub, 3, with its arm, 8,
extending into the groove 4, therein, and then the shaft, 6, is passed through said hub
causing the bar-portion of the pawl to enter the slot, a, in said shaft. Figure 1,
illustrates a portion of the shaft, 6, in operative position in the hub, 3, whereby one
end of the shaft-hole in the hub is tightly closed, and when said shaft extends quite
through the hub both ends of the shaft passage in the latter are closed, thereby shutting
the groove, 4, and its teeth, 5, and that part of the pawl which operates in connection
with the latter within said hub and preventing the entrance of dust and dirt whereby
the parts would be likely to become worn.
In further explanation of the above-described construction whereby dust is practically
excluded from entering said groove on the borders of which are the ratchet teeth, and
in which the pawl arm operates, it should be understood that that part of the pawl
which fits the groove in the shaft and moves therein serves to prevent dust from
entering the interior of the hub, 3, through the groove in the shaft at the end of
the latter.
The operation of the within-described improvements is exceedingly simple and is as
follows:
Referring to figure 1, if the shaft, 6, be rotated in a direction to carry the pawl, 7,
towards the teeth shown on the sides of the groove, 4, in that figure, the arm, 8, of
the pawl will strike one tooth after another on the opposite sides of said groove and
be thereby given a longitudinal reciprocating motion and will offer no resistance to the
rotation of said shaft; but if the shaft be rotated in the opposite direction the pawl, 7,
starting from any position within the hub, its arm, 8, will engage with one of the
teeth, 5, and cause the hub and the wheel to which it may be attached to rotate with
said shaft.
It will be seen from the above description of the manner of constructing the said
ratchet and pawl devices that the ratchet-teeth, 5, and the annular groove, 4, in which
they are located in the hub, 3, are cast in the latter in complete condition to operate
with the pawl and that the expense incurred in making the latter and in grooving the
shaft, 6, is very slight, and hence the expense involved in the construction of said
devices is reduced to a minimum.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed, as communicated to me by my
foreign correspondent, I declare that what I claim is:
A ratchet and pawl device consisting essentially of a hub closed at the end save for
a cylindrical shaft passage, and having an enlarged groove inside provided with teeth
extending in opposite directions, in combination with a grooved shaft extending through
the shaft passage in the hub, and a sliding pawl in the groove having an arm extending
between the ratchet-teeth in the hub, all substantially as described.
WM. P. THOMPSON & Co.,
Agents for the Applicant.