Improvements in Check Springs for Doors.
Year: 1891

page_text: Date of Application, 30th Apr., 1891
Complete Specification Left, 1st Feb., 1892-Accepted, 30th Apr., 1892
PROVISIONAL SPECIFICATION.
Improvements in Check Springs for Doors.
I SAMUEL SEALY ALLIN of 52 Woodstock Road, Bedford Park Chiswick,
London, W. Gentleman do hereby declare the nature of this invention to be as
follows:-
The objects of this invention are, First to produce a spring which will cause a
door to open with small resistance, and when opened to return slowly, till nearly
closed, finishing more quickly and strongly, and Secondly to produce a spring
which when fixed is invisible, and so to get rid of the unsightly external springs
now used, and of the connecting rods, cranks, levers, and joints, usually accompanying
them.
The ordinary pneumatic spring, or that depending on the resistance of a liquid
cannot well be used as an internal or invisible spring in consequence of its size, and
constructed as it is, its diameter cannot in practice be sufficiently reduced without
injuring its efficiency, but by the use of a special form of piston, a modification of
the form of the interior of the barrel in which it travels, and an adaptation of
valves, I am enabled to make a check spring small enough to be inserted in a door
or doorpost, and so to be completely out of sight, while it at the same time returns
the door, controls the speed of its motion, and finally closes it with force.
My apparatus consists of a barrel of cylindrical, oval, or other suitable section,
enclosing the spring & piston. This barrel is closed at its inner end, and its outer
end is fixed to a face plate, intended to be let in flush with the surface of the door
post, and having an opening, and a quadrant, or roller, guide projecting from it,
over which the flexible strap or chain leading from the piston to a plate, fixed on
the door, travels.
In this barrel is a spiral spring, under compression, and capable of being further
compressed so far as the travel of the door requires. Through this spring passes
the strap leading from the door to the piston, and as the door is opened, the strap,
or connecting link which may be of various constructions to meet varying conditions,
draws the piston forward, compressing the spring, which, when the door is left free
to return, again forces the piston back, against the resistance of the body of air
behind it.
The piston is so constructed that it will expand and contract, contracting when
moving in one direction, and expanding when moving in the reverse. This action can
be obtained in various ways, as for instance by a form of clack valve, or by
expanding rings, but the construction which I prefer, as simplest, and most effective
& durable, is that of a flexible piston face, somewhat similar to a cup leather,
combined with a wedge piece to expand it.
This elastic facing is supported by a metallic disc, and is not rigidly fixed to the
connecting strap, but is carried by a stud projecting from the wedge piece, to
which the strap or link is attached, and it is free to slide a small distance back-
wards or forwards on this stud.

page_text: The use of the wedge piece, which is adapted in shape to the facing of the piston,
is that when the piston is thrust back by the spring, it enters and expands it, thus
making a close joint with the inside of the barrel, while when the piston is drawn
forward by the strap, the wedge picce is first drawn out, and the elastic part of the
piston is left free to contract, thus diminishing resistance to the opening of the
door, and permitting the air to pass behind the piston.
This access of air is increased by a hole or holes passing through the piston,
which are closed by the wedge piece when the piston is being driven back by the
spring, but are open when it is being drawn forward.
The diameter of the barrel where the piston travels, is uniform, except at the
inner end. At that point where the piston arrives when the door is within say
3 or 4 inches of closing, it is relieved, or expanded, so as nearly to remove frictional
resistance, and to permit the spring to make its force effective in a strong action on
the door. In some cases where a very strong spring is needed, as with doors
exposed occasionally to wind, or violent swinging, it would be desirable to sub-
stitute a liquid resistance for that of air, when there would be no air holes in the
piston, but instead, a valve opening into a vessel underneath the barrel, containing
the liquid, this valve opening freely when the piston is drawn forward, and allowing
the liquid to enter rapidly behind the piston, and closing when the piston returns,
allowing the liquid to pass slowly back, a supplemental valve also giving relief at
the last moment when the piston is close to the end of its travel.
Dated this 30th da
1001
S. SEALY ALLIN.
COMPLETE SPECIFICATION (AMENDED)
Improvements in Check Springs for Doors.
I, SAMUEL SEALY ALLIN of 52 Woodstock Road, Bedford Park, London, W.
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:-
The objects of this invention are, to produce a spring which will offer small
1 csistance to the opening of a door, and will cause it when opened to return slowly
till nearly closed, finishing more quickly and strongly, and, secondly, to produce a
spring which when fixed is invisible.
In the accompanying drawing
Fig. 1 is a longitudinal horizontal section of a pneumatic check spring according
to my invention fixed in a door post.
Fig. 2 is a longitudinal vertical section of spring adapted for a liquid resistance.
Fig. 3 is a transverse section through the line a- Fig. 2.
Fig. 4 is a horizontal section of the mouth end of Fig. 2 showing chain and roller
guides, and
Fig. 5 is an alternative form of piston.
My apparatus consists of a barrel preferably of cylindrical section enclosing the
spring, piston and other parts.
This barrel A is closed at its inner end by the cover B, and its outer end is fixed
to a face plate C let into the door post D as shown in Fig. 1, or it may be fixed
behind it, the strap E in that case being prolonged to pass through the doorpost.
The face plate Chas in its centre an opening through which the strap E, or
chain F, passes, and at one or both sides of the opening a roller G or quadrant
guide H, over which passes a strap or chain from the piston to a pin Y fixed in the
door I.
Within the barrel A is a helical spring J, under suitable compression. Through
the spring passes the strap E or chain F, leading from the door to the piston.
The piston is composed of two parts, a wedge piece K, and a slightly elastic
facing L, in the nature of a cup leather, and preferably of leather.
This cup

page_text: leather is not rigidly attached to the wedge piece, but is free to slide a short way back
and forward on its stem M.
It is supported by a metallic ring N, and is lightly pressed toward the wedge
piece by a weak spring O, which in its turn bears against the disc P screwed on the
stem M. By turning this disc, the tension of the spring O can be regulated, and
the disc aids to prevent the piston from canting in the barrel. By this construction,
the piston contracts when drawn forward by the strap, and expands when thrust
back by the spring J. Thus in opening the door the friction of the piston is
reduced to a minimum and air enters freely behind it, but, on the return of the
piston in closing the door an almost air tight joint is made.
When the door is opened the first movement draws the wedge piece out of its
seat in the cup leather L which being in contact with the inside of the barrel, is
left behind, the spring O yielding easily, and air enters freely round the cup
leather, which is no longer pressed against the barrel, also round the wedge piece,
and on through a large opening in the cup leather. Thus the space behind the
piston is full of air ready to resist its return. The cup leather follows the wedge
piece at a short distance, in its forward movement, and on the first movement of the
door in its return, the spring J, thrusts the wedge piece back into its seat in the
cup leather, and makes a close joint all round, pushing the piston (wedge piece and
cup leather) slowly back against the resistance of the air behind until the air has
slowly leaked past the cup leather.
In order to facilitate the latching of the door, I very slightly enlarge the barrel
at a point such as Q at which the cup leather arrives when the door is within a few
inches of closing.
By this means I reduce frictional resistance and permit more rapid escape of the
air, thus enabling the spring to overcome the resistance of the doorlatch. In cases
where air resistance would be insufficient, I use liquid, and modify the apparatus as
shewn in Fig. 2, putting underneath the barrel a reservoir R to contain the liquid,
having a drain hole S to admit any liquid which may escape past the piston, a
diaphragm T descending nearly to the bottom to prevent air from being drawn into
the barrel, and an opening into the barrel closed by the valve U; through this
valve is a small hole V, through which the liquid escapes into the reservoir when
the piston is being forced back, and the valve projects forward, so that the disc P,
when the piston is near the end of its return stroke comes in contact with it, and
lifts it, allowing the liquid to escape rapidly into the reservoir. This arrangement
is a substitute for the enlargement of the barrel at Q in the pneumatic form shewn
in Fig. 1.
In Fig. 5 is shewn un alternative form of piston, in which the contraction of the
diameter of the piston is effected by the air pressure lifting the leather portion W
from its seat. When the piston is drawn forward the leather is raised against the
resistance of the spring X, its edge thus leaving the barrel at those points where it
lifts. When the piston is pushed back, the leather is pressed by the air or liquid
behind it on to its sent its edge bearing against the barrel all round, its diameter
being thus increased-and-diminished according as it is moved backwards or
forwards.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim
in respect of door check springs is :
1. In combination with the spring barrel, a piston to work therein cousisting of
two parts the one part operating as a wedge to expand the other part when the
piston moves in the one direction and allowing the other part to contract when the
piston moves in the other direction, substantially as and for the purpose herein set
forth.
2. The modified form of piston substantially as described with reference to
Fig. 5.
3. In apparatas such as is above referred to the enlargement of the barrel as the

page_text: piston approaches the end of its instroke, substantially as and for the purpose-set
forth.
4. 2. In combination with the spring barrel and its adjuncts a liquid reservoir and
valve arranged and operating substantially as described with reference to Figs. 2, 3
and 4.
ABEL & IMRAY,
Agents for the Applicant.