Improvements in Door Springs and Checks.
Year: 1891

page_text: Date of Application, 13th Nov., 1891-Accepted, 19th Dec., 1891
COME LEIE DI MOITICATION.
Improvements in Door Springs and Checks.
JOHN SANDERS STEVENS and CHARLES GEORGE MAJOR, Engineers,
"Janus" Works, Queen's Road, Battersea, in the County of Surrey, 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:
Our invention relates to that class of springs for closing doors which are
combined with a check to prevent slamming consisting of a cylindrical dash pot
or cataract, the checking or resisting medium being oil escaping through a con-
tracted orifice; and it has particular reference to our Letters Patent Nos. 5281
November 8th 1883, 5925 December 29th 1883, and 2626 February 26th 1885,
upon the same subject.
In one of our previous Patents referred to viz. 2626 A.D. 1885, the pivot of the
door was coupled up to the checking apparatus by a double interlocking cam
arrangement, which only allowed the pivot to revolve as one of its cams was
gradually released by the slowly advancing piston rod from the cataract cylinder,-
the piston rod being provided with a heart shaped head for the purpose. The
pivot carried an arm furnished at its extremity with a pin which swept round the
outside of the heart upon the piston rod, the pin being only enabled to continue its
sweep as the heart retired to make way, and the revolution of the pivot was
continued at the requisite pace by the head of the piston rod pressing against a
second arm on the pivot.
Mechanically this device gives the desired result-but the space at disposal does
not allow of the checking: arm and pin on pivot being made sufficiently strong to
resist the strain if the door should be forced home against the resistance of the oil
cataract.
In our present invention we retain the same cam arrangement A as before for
causing the pivot B to revolve as the piston rod C advances, but for the purpose of
obtaining a stronger check mechanism we exactly reverse the checking cams.
That is to say we remove the heart cam from the piston rod head, and place it
upon the pivot in the shape of a second arm D which is short and strong; and we
construct the piston rod head E E in the shape of a stirrup, with a suitably formed
interior outline, within which both arms A and D upon the pivot revolve. The
outline of the two arms A and D upon the pivot, and of the interior surface of
stirrup E, are so formed that the pivot B will drive the piston rod C in either
direction i.e. into or out of the cylinder F, or the piston rod will drive the pivot in
either direction to right or left; but if the piston rod be set fast no motion of the
pivot is possible, nor can the piston rod move if the pivot be stationary. In short
the whole system is locked together in all positions though still capable of mutual
motion.
This arrangement will close and check a swing door when opened either way.
As a farther precaution against breakage by forcibly closing a door against the
check action, we place behind the oil piston G a small spring H, so that in the
case mentioned if the oil cannot escape quickly enough by the regulating passage I,
the piston will slide along the rod C compressing the small spring H behind it.
As the oil escapes from F under the pressure of the main spring J, the piston G
and its relief spring H resume their proper positions.
Our invention farther relates to an improved method of admitting the oil to the
cylinder, uamely by a small valve K playing vertically in a chamber L made in
one piece with the cylinder, and cominunicating therewith by a passage M. The
oil escapes through the upper portion of chamber L passing a regulating or

page_text: throttling screw as before. We apply this device to springs described in all the
Letters Patent hereinbefore referred to instead of fitting a valve in the piston G,
which is made solid.
DESCRIPTION OF DRAWINGS.
Fig. 1 is a plan of the apparatus with the cover plate removed, and the cylinder
with piston in section.
Fig. 2 is a vertical section of same on line X Y.
Fig. 3 is a vertical section of cylinder and piston shewing the position of improved
vertical valve.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
(1) In combination with a door spring and check such as described in our Letters
Patent No. 2626 A.D. 1885 the arrangement of interlocking cams as and for the
purpose herein described.
(2) In any door spring having a check cylinder in which a liquid is employed,
the use of a relief spring behind the piston as & for the purpose described.
(3) In combination with any door spring forming the subject of either of the
Letters Patent hereinbefore referred to, the application of a valve placed in
position as shewn in Fig. 3-as and for the purpose described.
Dated this Thirteenth day of November 1891.
JOHN SANDERS STEVENS.
CHARLES GEORGE MAJOR.