Improvements in Check Springs for Doors.
Year: 1892

page_text: Date of Application, 22nd Feb., 1892
Complete Specification Left, 21st Nov., 1892-Accepted, 31st Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in Check Springs for Doors.
1, SAMUEL SEALY ALLIN, of 52 Woodstock Road, Bedford Park, Chiswick,
London, Gentleman, do hereby declare the nature of this invention to be as
follows:-
In my Specification No. 7497 of 1891 I have described a construction of check
spring for doors in which a piston linked to the door works in a cylinder let into
the door post, the piston being urged by a spring in the direction tending to close
the door, but being resisted by the air or by liquid in the cylinder behind it.
My present invention relates to check springs of this kind and has for its objects
appliances for rendering them more effective, for adjusting the fluid resistance and
for holding open in certain positions the doors to which such check springs are
applied. make the face plate which covers the mouth of the cylinder with a tube
projecting into the cylinder, which tube forms a guide for the piston stem sup-
porting it against the lateral strain of the link which connects the piston stem to
the pin on the door. By selecting a position for this pin in the door style and
varying the length of the connecting link the door may be held more or less open
and the force of the spring may be so far reduced in respect of leverage that the
speed of the closing is moderated notwithstanding the extreme compression of the
spring.
From the face plate of the cylinder also projects inwards at the side of the guide
tube a tube of section which is not circular and which can be turned by a screw
driver. Into this tube projects the non circular stem of an adjusting screw
governing a hole in the piston.
By turning the tube and thereby turning the adjusting screw, the stem of which
travels within the tube, the hole of the piston can be more or less opened or entirely
closed so as to allow more or less or no passage of fluid through the hole, the resistance
being thus regulated. When the resistance is that of air, I provide at the end of
the cylinder a valve which is usually kept closed by a spring but which is opened
by the piston as it approaches the end of its instroke bearing on the stem of the
valve thereby allowing escape of air so that the piston in the last part of its stroke
encounters very little resistance and the door is closed with sufficient force to
engage the latch. The stem of this valve can be adjusted by a screw so as to be
opened sooner or later by the piston.
When the check spring is applied to a door swinging both ways I provide for
retaining the door in its middle closed position or in either of its open positions by
fitting a spring stud in the hinge plate fixed in the lintel above the door, which
stud projects into shallow recesses formed in the hinge plate fixed on the upper
rail of the door, so that it requires some force to dislodge the stud from the middle
recess which it enters when the door is closed or from either of the extreme recesses
which the stud enters when the door is fully opened in either direction.
Dated this 22nd day of February 1892.
ABEL & IMRAY.
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Chéck Springs for Doors.
I, SAMUEL SEALY ALLIN, of 52 Woodstock Road, Bedford Park, Chiswick,
London, Gentleman, 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 :—
In my Specification No. 7497 of 1891 I have described a construction of check
spring for doors in which a piston, linked to the door, works in a cylinder let
into the door post, the piston being urged by a spring in the direction tending
to close the door, but being resisted by the air or by liquid in the cylinder
behind it.
My present invention relates to check springs of this kind and has for its
objects appliances for rendering them more effective, for adjusting the fluid
resistance and for holding open in certain positions the doors to which such check
springs are applied, as I shall describe referring to the accompanying drawings
which shew check springs constructed generally as described in my former Speci-
fication No. 7497 of 1891, but with modifications according to my present
invention.
Fig. 1 is a longitudinal horizontal section and Fig. 2 an end view of the check
spring adapted for air resistance.
Fig. 3 is a longitudinal section and Fig. 4 is a transverse section of the cylinder
adapted for the resistance of a liquid such as glycerine.
Fig. 5 is a part section shewing a flexible strap instead of a link for connecting
the door to the piston.
Fig. 6 is a part section shewing a modified form of piston.
Fig. 7 is a part sectional plan shewing the spring check applied to a door swinging.
both ways.
Figure 8 is a section and Fig. 9 is a plan shewing the means of holding a swing
door in its middle and extreme positions.
Referring to Fig. 1, A is a cylinder fixed in the jamb D to which is hung a
door by the hinge B. From the plate C which covers the mouth of the cylinder A
projects inwards a tube H forming a guide for the piston stem I which is connected
by a link F to a pin b fixed in a recess of the door hinge. When the door is so
far opened that the link F takes a position such as is indicated by the dotted line f
nearly in line with the axis of the hinge, the door remains open. The position of
the pin 6 and the length of the link Fare such that the door when it begins to
close is subject to comparatively little spring force, this force acting at a dis-
advantageous leverage. Instead of employing a link F, as shewn in Fig. 1 for a
door opening one way, and in Fig. 7 for a door opening both ways, a flexible
strap E may be used as shewn in Fig. 5 and as described in my previous Speci-
fication, in which case, by employing a segment 6 on which the strap E bears, the
guide tube H shewn in Figs. 1, 3 and 7 can be dispensed with.
To the stem I is attached a piston consisting of two parts as described in my
previous Specification the one part M of conical form externally fitting into the
other internally coned part N which is of leather or such like flexible material and
is free to move on the stem but is urged towards M by a light spring Q bearing on
a washer the force of this spring being adjustable by screwing more or less
forward a nut R.
This nut is preferably made of the same diameter as the cylinder A so that it
serves to guide the piston stem. Between the part M of the piston and the cover C
of the cylinder is placed a helical spring J under sufficient strain to effect the
closing of the door. When the door is opened it is resisted by this spring but the
part M of the piston being withdrawn from N, air can freely pass into the space of
the cylinder behind N. On letting go the door the spring J presses the part M of

page_text: the piston into the part N expanding the lip of N so that it fits closely to the
internal surface of the cylinder A, and the air, imprisoned behind it, becomes
compressed, retarding the movement of the piston inwards and so retarding the
closing of the door. In order to regulate this retardation by allowing more or less
air to pass the piston, I make a hole through M and fit it with a screw plug T
which is grooved or flattened on the side and has a long stem entering a tube U
having a head W notched so that it can be turned by a screw driver. The stem
of the plug T and the tube U being of section not circular, by applying a screw
driver to turn the tube U the plug can be more or less unscrewed so as to allow
passage of air along its flat side or groove, or it can be screwed home with a
packing washer under its head to close completely the passage through the piston.
Instead of employing the tube U with a screw driver head W for turning the
stem of the plug T, this stem may be made circular in section so as to be merely
guided in the tube U (which would be also circular) and of such length that when
the door is opened the end of the stem projects beyond the end of the cylinder, so
that it can be turned by a screw driver or key, thereby adjusting the plug T.
Though it is desirable to retard the door during the greater part of its closing
movement, it is generally desirable also to leave the last part of the movement
unimpeded, so that the door can close with sufficient force to latch itself.
In order to provide for this I make the end part of the cylinder A from some
point such as X of a little larger diameter than the rest of the cylinder so that,
when the piston moves along this enlarged part, air can find its way from behind it
thus relieving the pressure acting against the piston.
Instead of this arrangement which was described in my former Specification, a
like result can be attained by fitting in the bottom of the cylinder a plug valve n
which is usually kept closed by a spring o but which is opened allowing escape of
air when the stem of the piston meets the stem p of the plug u. By screwing the
stem more or less forward the escape of air can be made to take place sooner or
later during the closing of the door.
When liquid such as glycerine is used to retard the piston I provide, as described
in my former Specification and as shewn in Figs. 3 and 4, a reservoir Y for the
liquid under the cylinder A and communicating in front with the cylinder by a
hole Z which is always open, and behind by a hinged valve b having a small hole
through it, this valve being situated behind a partition a which extends nearly to
the bottom of the reservoir Y. As the piston is drawn forward in opening the
door, liquid can flow freely from under the partition a, past the valve b which is
open into the cylinder A behind the piston.
But, when the piston moves back in closing the door, the valve 6 closes and the
liquid can only pass through the small hole in the valve, the movement of the piston
being thus checked. As the piston approaches the end of its instroke the nut R
meeting the projecting end of the valve b opens the valve, thus relieving the
resisting pressure and allowing the door to make the last part of its closing move-
ment with sufficient freedom to become latched. Such liquid as may pass the
piston flows back into the reservoir Y through the hole Z.
The modified form of piston shewn in Fig. 6 consists of two disc parts M¹ which
is rigid and N¹ which is flexible being of leather or equivalent material pressed
against M' by a spring Q. When the piston is drawn forward in opening the
door, fluid bending N¹ from M' can freely pass to the space behind the piston, but,
when the piston makes its back stroke in the closing of the door, the fluid behind
the piston presses the edge of N' forwards so that it fits closely against the internal
surface of the cylinder A, thus preventing the fluid from passing the piston.
For holding a swing door steadily closed in its middle position and holding it
open in either of its extreme positions, I adopt the arrangement shewn in Figures 8
and 9. In the frame or plate, which is fixed in the lintel above the door to hold
the upper hinge pin S, I fit a vertically sliding studs which is pressed down by
a spring.
In the plate S', which is fixed on the top edge of the door to receive the hinge

page_text: pin S, I make a central shallow recess s¹ and two recesses s² 3 in such positions
that the end of the studs can engage in them holding the door in its middle and in
its extreme positions with certain steadiness, but, the end of the studs and the
recesses being sloped, the door can be moved by the exertion of a little force.
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 in respect of check springs for doors of the kind described in my former
Specification No. 7497 of 1891, is :-
1. A. guide tube such as H for the piston stem I, substantially as described.
2. A screw plug such as T in the piston for regulating passage of fluid through
the piston, substantially as described.
3. An outlet valve such as n in the cylinder bottom with spring o and adjustable
stem p, substantially as and for the purpose set forth.
4. In combination with the upper hinge of a swing door, a spring stud such as s
engaging in shallow recesses so as to hold the door in one of their positions,
substantially as described.
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31
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1000
ABEL & IMRAY,
Agents for the Applicant.