Hydraulic Ratchet and Pawl Apparatus.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Hydraulic Ratchet and Pawl Apparatus.
I, JOSEPH ALBERT DEPORT, of No. 19 Rue de la Rochefoucauld, Paris,
France, do hereby declare the nature of this invention to be as follows:-
This invention relates to apparatus wherein a pawl mounted on the piston of
a hydraulic cylinder is moved to and fro acting on a ratchet which may be on
a straight rack or on the circumference of a wheel or segment so as to cause a
movable frame carrying the cylinder and pawl to move step by step, or to cause
the rack wheel or segment to move step by step in the opposite direction. For
this purpose, a cylinder is provided with a differential piston on the end of which
is pivotted a bell crank lever, one of its arms constituting a pawl, its other arm
being linked by a flexible connection to a spring and to the rod of a slide valve
which works in a slide casing on the side of the cylinder. The small annular
area of the piston is always subject to the pressure of the water, the larger area
is alternately subjected to and relieved from the pressure by the action of the
slide valve, the pressure on the large area causing the piston to advance, and
the pressure on the small area causing it to retreat when the pressure ou the
larger area is relieved by the opening of the outlet port of the slide casing.
Besides the spring above mentioned as linked to the pawl arm, another spring
of less strength has its one end linked by a flexible connection to the bydraulic
piston rod, and its other end connected to one arm of a hand lever the other
arm of which is connected to a sliding frame attached to the rod of the slide
valve. The apparatus operates as follows:
When the piston is in its back position both springs are unstrained, and the
pawl is behind a tooth of the ratchet; on the slide valve being moved by the
hand lever so as to admit water under pressure behind the piston, the piston
advances, and after it has moved a certain distance it strains both springs the
one being linked directly to the piston and the other linked to the arm of the
pawl lever which is prevented from moving by the frictional pressure of the pawl
upon the tooth. When the piston reaches a stop this frictional pressure is
relieved, and thereupon the one spring draws the pawl out of engagement and
becomes itself relieved of strain; the other spring then draws the hand lever
and slide valve back, and the outlet port being thus opened, the piston makes
its back stroke.
Instead of reversing the slide valve by a hand lever it may be moved auto-
matically by tappets in any known manner. When it is desired to effect motion
in both directions two sets of the hydraulic apparatus are arranged on one frame
to act on opposite ratchet teeth.
Dated this 10th day of April 1895.
ABEL & IMRAY,
Agents for the Applicant.

page_text: I, JOSEPH ALBERT DEPORT, of No. 19 Rue de la Rochefoucauld, Paris,.
France, 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 apparatus wherein a pawl mounted on the piston of a
hydraulic cylinder is moved to and fro acting on a ratchet which may be on a
straight rack or on the circumference of a wheel or segment so as to cause
a movable frame carrying the cylinder and pawl to move step by step, or to cause
the rack, wheel or segment to move step by step in the opposite direction.
I shall describe apparatus according to my invention referring to the accom-
panying drawings.
Fig. 1 is an external elevation the piston being towards the end of its out stroke,.
Fig. 2 is a similar view the piston being retracted;
Fig. 3 is an end view and Fig. 4 is a longitudinal section of the cylinder and
slide valve,
Figs. 5 and 6 shew in section and plan respectively the application of the
apparatus for working the platform Z of a gun turret.
The cylinder A is provided with a differential piston B on the end C' of which
is pivotted a bell crank lever C, one of its arms constituting a pawl engaging in a
ratchet rack D. The cylindrical slide valve F works in a casing E having
grooves a. The ends of F are fixed to a frame G having a slot H, in which is
fitted a sliding block K linked by a pin a to the controlling lever I, which is
fulcrumed at J.. A spring L has one end connected by a flexible connection d to
the head of the piston B, its other end being attached to an arm of the lever I.
A stronger opposing spring M has its one end attached to the slide casing E, and
its other end attached to the front part of the frame G which is fixed on F and
attached by a flexible connection b to the arm of the bell crank C. The pawl C
can be raised by a T headed chain and spring O which can be attached to a
hook P.
Qis the pipe which supplies high pressure water, R is the exhaust.
The port S admits water to A causing the piston to make its forward stroke, the
port T communicates with the annular space around the smaller part of the
piston. The small annular area of the piston is thus always subject to the pressure
of the water, the larger area is alternately subjected to and relieved from the
pressure by the action of the slide valve, the pressure on the large area causing
the piston to advance, and the pressure on the small area causing it to retreat when
the pressure ou the larger area is relieved by the opening of the outlet port of the
slide casing.
The apparatus operates as follows:-
When the piston is in its back position as in Fig. 2, both springs L and M are
unstrained, and the pawl C is behind a tooth of the ratchet rack D; on the slide
valve F being moved by the hand lever so as to admit water under pressure behind
the piston, the piston advances, and after it has moved a certain distance it strains
both springs the one L being linked directly to the piston and the other M linked
to the arm of the pawl lever C which is prevented from moving by the frictional
pressure of the pawl upon the tooth. When the piston reaches a stop U this
frictional pressure is relieved, and thercupon the spring M draws the pawl out of
engagement and becomes itself relieved of strain, the other spring L then draws
the hand lever I and slide valve F back, and the outlet port being thus opened as
indicated by the dotted lines at x x Fig. 4. the piston makes its back stroke in
obedience to the pressure on its annular area, on which high pressure water still

page_text: acts, passing by the grooves xx and port T to the annular space. The piston is.
gradually arrested by the plunger V entering a cavity in the piston and throttling
escape of water therefrom.
Instead of reversing the slide valve by a hand lever it may be moved auto-
matically by tappets in any known manner.
When it is desired to effect motion in both directions, two sets of the hydraulic
apparatus are arranged on one frame to act on opposite ratchet teeth, the pawl not
in use being held out of gear by the hook P.
Having now particularly described and ascertained the nature of this inveu-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. Hydraulic ratchet and pawl apparatus comprising a hydraulic cylinder with.
slide valve, and piston carrying a pawl engaging in a ratchet rack, substantially as
and for the purpose set forth.
2. In combination with the piston, pawl and slide valve above referred to a pair
of opposing springs determining the back stroke of the slide valve when the piston
completes its forward stroke, substantially as described.
3. The use of the apparatus above referred to for acting on a fixed rack so as to
move the platform carrying the apparatus, or for acting on a moveable rack, the
apparatus being itself stationary.
Dated this 9th day of December 1895.
ABEL & IMRAY,
Agents for the Applicant..