AN IMPROVED PNEUMATIC DOOR CHECK-SPRING
Year: 1885

page_text: I, JOHN CORRY FELL, of the firm of Fell & Wilding, of 1 Queen Victoria Street,
in the City of London, a Fellow of the Institute of Patent Agents do hereby
declare the nature of the said invention for "AN IMPROVED PNEUMATIC DOOR
CHECK-SPRING," a communication to me from abroad by Felix Isidoro Gazaix, of
28 Rue du Faubourg, Saint Denis, Paris, Lock Smith to be as follows:-
--
This invention relates to a door check-spring, which is dependent for its action
upon the resistance of a cushion of air, and has for its object the prevention of the
sudden and noisy closing of the door, in a simple and efficient manner, the closing
action of the spring being rendered as quiet and easy as may be desired.
The device consists of a cylinder in which moves a piston, provided with a cup
leather, and surrounded, on the side opposite to that of the cup leather, by a spiral
spring. The spring is compressed by the opening of the door itself, through the
operation of certain arms and levers, hereinafter more fully described, and at the
same time, the piston, by its movement, draws in air between the piston and
the fixed bottom of the cylinder. To effect the closing of the door, the spring
expands, and operates the piston, causing it to descend into the cylinder, pushing
before it the air stored up in the closed cylinder, and forcing it to escape by one or
more small orifices, which may be regulated by means of a screw or other suitable
device. The door thus closes as quietly and softly as may be desired, and can at
need be caused to stand ajar by closing completely the orifice for the escape of air.
The admission of the air into the cylinder on the up stroke of the piston is
provided for by a suction valve, admitting the inflow of the air against the
reaction of a light spiral spring, which causes the valve to return to its seat
immediately on the return stroke of the piston. The escape of air, to allow the
gentle closure of the door, is permitted through a tapped hole in which a screw is
fitted, the screw and hole being marked with a file groove to allow the passage of
air between them. The size of such passage may be regulated by turning the
screw, so as to bring the grooves more or less relatively opposite one another.

page_text: The cylinder is attached by a hinged joint to the fixed cill of the doorway, the
external end of the piston rod being attached to a lever of which the other end is
also carried on a hinged joint attached to the said door cill. To the door is
attached, by a pin joint, a rod, of which the other end operates the before mentioned
lever, which is hinged to the door cill, and to which also the head of the cylinder
piston is attached.
The opening movement of the door is thus communicated through the hinged.
lever to the piston head, and the before-described suction stroke of the piston is
produced. The recoil of the spring within the cylinder effects the closure of the
door, the imprisoned air cushion under the piston rendering the closing gradual
and gentle.

page_text: the stalk of the valve, and at the other rests upon the plug f, in a suitable hole,
which serves as a guide for the valve.
At the opening of the door the piston c produces an indraught of air, the valve i
lifting and allowing the air to enter into the cylinder a. During the closure, the
piston, pressed by the spring b, compresses the air, closes the valve i, and the only
exit for the air is the small groove between the screwed plug hole, and the tapped
hole in which it fits. The piston thus produces a discharge of air, regulated in
amount by the screw o, and there results a cushion of compressed air, which
opposes itself to too sudden a closing of the door.
The apparatus is fixed to a door as follows:-
The cylinder a is jointed to the cill m by means of a bracket n, which carries a
hinge pin p, on which the cylinder is free to oscillate. The rod b of the piston is
attached, by means of a pin q, to a lever r, which has its other extremity at 8,
jointed by a pin to the bracket t, also fixed on the cill of the door. The head of
the lever r is provided with a double fork, so that it carries also the head of a
rod u, which is jointed by a pin v to a bracket x fixed on the door y. This rod u
gives, during the opening of the door, a lifting movement to the piston c, bringing
the rod b with it; in the movement of shutting, it is, on the contrary, the rod b of
the piston, which, pressed by the spring d, pulls on the rod u, and pushes the door
to shut it.
Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, I declare that what
I claim is
In a pneumatic door check-spring, operated by the elasticity of the air, drawn
into a cylinder at the opening of the door, and discharged at its closing, in order to
render the action of the closing spring as gentle as possible :-
1st The construction of the device ol to regulate the action of the air, by giving
it in escaping an orifice of egress more or less great, as desired, substantially as
described.
2nd The construction of the suction valve., in combination with the before
claimed tapped orifice and adjusting screw o, substantially as described.
3rd The method of application of my device to a door, consisting of the cylinder a,
jointed to the cill m, and the lever u fixed to the door, the parts being rendered
movable by their hinged joints with a rod r and with the brackets nt x, sub-
stantially as and for the purposes specified.
Dated this 14th day of January 1886
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