Improvements in Door-checks.
Year: 1891

page_text: Improvements in Door-checks.
I, BRUNO MÄDLER, of 112, Köpnickerstrasze, Berlin, in the Empire of Germany,
Manufacturer, 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 :-
My invention relates to door-checks.
With the apparatus heretofore employed for preventing the slamming of doors
it frequently happens that in case the door is pushed to by hand such apparatus
fails to fulfil their object.
When the door is opened so that the piston B is at the upper end of its stroke in
the cylinder A, Figure 1, the compressed spiral spring f, on the release of the door,
will force the piston downwards, thereby closing the door. In the regular operation
of the apparatus too rapid a closing is prevented by the compressed air in front of
the piston, this air being allowed to escape but slowly through a taper groove
provided in the screw which may be suitably adjusted. It is only at the moment
when the rear edge of the piston uncovers the orifice a of an auxiliary air-
channel e, e', a that the compressed air in front of the piston can rapidly pass
through this channel e, e', a into the space C behind the piston which communicates
with the atmospheric air, so that the pressure of the air in front of the piston is
speedily reduced and the aforesaid spring is capable of forcing the piston quickly
down to the bottom and closing the door.
This regular action does not however take place when the door is pushed to by
hand.
The pressure exerted upon the door, upon the levers connected with the piston-
rod, and upon the piston-rod itself, materially assists the spring in pressing down
the piston. When the rear edge of the piston is caused by the continued pressure
from outside to pass beyond the orifice a the piston is suddenly relieved, as the air
in front of the piston can escape through the channel e, e, a to the space C, so that
the door is slammed owing to the pressure from outside in conjunction with the
pressure exerted by the spring f whose action is unlimited.
This defect is remedied by the employment of a valve which is shown in Figure 1
and to an enlarged scale in Figure 2.
In front of the part e¹ of the air-channel e, e', a, I provide a ball-valve, the ball.
of which rests upon a screw s. The latter is adapted to be screwed into the air
channel only to such an extent that the ball does not quite touch its seat and is
situated somewhat higher than the orifice e of the aforesaid channel.
I place in the part e¹ of the air channel a spiral spring which tends to keep the
said valve open, that is to say, force the ball a downwards. The tension of this
spring is such that at the ordinary pressure of the air in front of the piston the
valve is just kept open, but when this pressure is increased, for instance by a
pressure from outside exerted upon the piston as above stated, this higher air-
pressure will force the ball upwards against its seat w and hold it there, thus
preventing the further passage of the compressed air from the space in front of the
piston to the space C. By this means the piston will be caused to descend
uniformly to the end of its stroke and the door will not be slammed.
The lift of the ball can be adjusted by the screw s.
This arrangement can also be employed for door-checks in which liquid, for
example oil, glycerine or the like is used in lieu of air.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
:-
In door-checks the arrangement of a valve in front of the channel e¹ connecting
the two openings e and a, in such a manner that in the regular operation of the
door-check the said valve is held open by a spring, but is closed for preventing the
slamming of the door when the pressure of the air below the piston B is increased
to an excessive degree.
Dated this 29th day of January 1891.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.