Year: 1886

page_text: Date of Application, 28th Oct., 1886.
Specification Accepted, 15th Feb., 1887.
I, OSKAR LEUNER, Manufacturer, of Dresden in the Kingdom of Saxony, 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 apparatus hereinafter described serves for measuring and graphically drawing
the deflections of loaded bridges.
The apparatus is fixed by the binding screws a¹ a² (figures 1 and 2) to any part of
the bridge to be examined. It is put into effect by fixing one end of a stretched steel
ribbon to a fixed point, as for instance a weight at the bottom of the river underneath
the bridge, whilst the other end is attached to the bridge itself in such a way that the
ribbon shortened by the deflection of the bridge will mark the deflection on the same
or on a larger scale on a paper strip wrapped round a drum which may be rotated by
hand.
For this purpose the apparatus is provided with a frame carrying stepped
pulleys in centres.
On the other end of the frame is placed the spring barrel e which is connected with
the largest (3) of the pulleys, by the steel ribbon c, on which latter again there is
fastened the pencil d. The said pencil works loose above the paper drum i, which is
also placed in the frame in a position parallel to the direction of motion of the pencil
and provided on the one side with the worm wheel that engages with the worm 7.
By turning the winch candle, the paper drum is slowly rotated. The cylinder is
covered with white paper and the latter is tightened by the cross-band n.
The spring
barrel stretches the steel ribbon c constantly in the direction of the arrow. While the
one pulley is rigidly connected with the steel ribbon c, a steel ribbon g is fastened
to one or other of the pulleys 66. The ribbon is connected by a clamp with a wire
which at its lower extremity bears the weight resting on the bottom of the river.
By turning the winch crank h of the axis of the spring barrel e, the spring is wound
up and held in position by the locking devices (cogwheel and pawl).
Now when measuring the deflection of a bridge, the apparatus is first fixed to a
part of it, then the weight g¹ must be sunk to the bottom of the river whilst the wire
attached to this weight is fastened in the clamp of the steel ribbon g. This latter must
previously be fixed to one of the pulleys b¹².

page_text: After this the spring in the barrel e and thereby the wire are stretched, and the
pencil d is put as near as possible to the pulleys.
If now the bridge is loaded, the distance of the apparatus from the bottom of the
river will rapidly be diminished in consequence of the deflection. Thereby the wire
previously stretched gets loose and is wound up on the spring barrel by means of the
steel ribbon c. In consequence of the movement of the steel ribbon the pencil d, which
is fastened on the steel ribbon c is also carried along and describes on the paper covering
the drum, a straight line in the direction of the steel ribbon c. If on the contrary the
paper drum i is turned by the winch crank m, the pencil will draw a diagram corre-
sponding to the deflection of the bridge.
If the weight on fixed point be connected by wire and steel ribbon with the middle
pulley, the absciss a in the diagram, and the deflection of the bridge will be in the
proportion of 1 to 2, but if the wire be connected with the smallest pulley 61, the
the absciss a in the diagram and the deflection of the bridge will be as 1 to 5.
Having now particularly described and ascertained the nature of my said Invention,
and in what manner the same is to be performed, I declare that what I claim is :-
A deflectometer by which the diagram is drawn on the paper by a paper-drum i,
which is turned by hand through the aid of worm 7, worm wheel k, and winch crank m,
substantially as herein shewn and described.
HUGHES, ELI & HUGHES,
76, Chancery Lane, London, W.C.,
Agents for the Applicant.