Improvements in or relating to Apparatus for Indicating and Registering the Vibration or Deflection of Bridges and other Structures.
Year: 1892

page_text: Date of Application, 14th Mar., 1892
Complete Specification Left, 12th Jan., 1893-Accepted, 18th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in or relating to Apparatus for Indicating and
Registering the Vibration or Deflection of Bridges and other
Structures.
I, EMILE PARENTHOU, of 95 Boulevard Beaumarchais, Paris in the Republic
of France, do hereby declare the nature of this invention to be as follows :-
:-
This invention relates to apparatus for indicating and registering the variations
of deflection of parts of structures such as beams or girders of metal bridges and is
based upon a principle which may be illustrated as follows,―
Supposing a vessel placed at any desired point upon the girder to be tested,
contains water, mercury, petroleum or other liquid and is filled up to a pre-
determined level. This vessel is connected by a tube with another vessel stationary
in any desired position off the bridge or at a place not affected by the deflection of
the structure. The joint action of these two connected vessels will be that any
deflection of the girder at the point where the first vessel is placed will effect a
corresponding alteration of the level of the liquid in the second vessel.
The apparatus may consist of a number of vessels hereinafter called "movable
vessels "corresponding to the number of different parts of a structure to be tested
these may be secured to the various parts of the structure in any
desired manner
and are each connected to its corresponding distant vessel which is adjustable and
which is hereinafter called a "stationary vessel," by a tube.
In each of the stationary vessels is provided a float supported on the surface of
the liquid contained therein and each float is adjustably connected by a cord, lever.
and shaft or equivalents to a peucil or other marker-carrier, the weight of the float
being if desired counteracted by a counter weight secured to the shaft. A
uniformly rotating cylinder is arranged in front of the marker-carriers which
indicate upon the surface of this cylinder the oscillations corresponding to the
movements of the floats. The rotary motion may be imparted to the cylinder by
means of an electro-magnet which by attracting an armature lever operates a pawl
and ratchet wheel the shaft of which may be connected by worm gearing with that
of the cylinder.
To obtain regular motion at a speed varying according to the nature of the test
to be made the electro-magnet may be operated by means of an automatic com-
mutator producing a uniform number of interruptions of current in a predetermined
unit of time during the whole time that-the test lasts.
The paper or equivalent strip upon which the records are taken is stored on a
roller and is wound on the cylinder after receiving the recording marks. Another
marking device for indicating the number of oscillations produced by the markers
in the various tests may reciprocate under the action of a vibrator and produce
a number of short lines or dashes on the paper.
A series of equidistant markers placed above the cylinder trace upon the paper
a series of equidistant parallel guiding lines. These last mentioned markers are
carried in a frame preferably divided into two parts so that at each operation the
registering markers may always be brought back to the lines representing zero.
The markers may be moved out of contact with the paper by any convenient
means such as a frame mounted on a shaft bearing against the marker carrier and
which receives motion from an electro-magnet.
The registering apparatus herein described owing to its being controlled by
electricity may be arranged at any distance from the point tested and the operator
is in a position to control a number of testing apparatus at the same time provided
the various electrical circuits have a common centre of oneration.

page_text: The commutator is constructed of, preferably four conducting and four non-
conducting rings, the non-conducting rings however being provided with conducting
parts the number of which may increase at'a ratio of 1, 3, 6 &c. the last being a
continuous conductor.
•
When the apparatus is to serve for registering minimum and maximum strains it
may consist of two horizontal glass tubes one end of each of which dips down into
mercury contained in a suitable vessel.
'
When the before described test vessels are arranged in place a small plunger is
pushed down into the mercury whereby a column of the mercury is caused to rise
in each of the tubes while a second plunger arranged near one: of the terminal
vessels enables the mercury to be returned to zero. Two small indices such as are
used in thermometers are introduced into the two tubes to indicate. the extreme
alterations of level and these indices may be moved back to their zero position by
a magnet or equivalent means.
To facilitate the reading off of the modifications of level there may be employed
two tubes controlled by a cock and fitted with a U-shaped tube containing mercury.
and fitted at their upper ends into a chamber also provided with a cock or valve
for controlling the admission of air. The pipes are connected to two reservoirs
one stationary and the other movable with or according to the deflections of the part
to be tested.
The before described apparatus may be modified without departure from the
spirit of the invention.
Dated this. 14th day of March 1892
W. P. THOMPSON & BOULT,
Agents for the Applicant
COMPLETE SPECIFICATION.
Improvements in or relating to Apparatus for Indicating and'
Registering the Vibration or Deflection of Bridges and other
Structures.
I, EMILE, PARENTHOU of 95 Boulevard Beaumarchais, Paris in the Republic
of France, 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 :-
This invention relates to apparatus for indicating and registering the variations
of deflection of parts of structures, and particularly beams or girders of bridges, no
matter under what circumstances or conditions the test may be made, and the
apparatus hereinafter described will also be found applicable in cases where
continuous beams or girders have a number of points of support, being adapted
accurately to record deflections under either stationary or moving loads, and even
when the bridge or the like is in actual use.
The principle of the invention may be illustrated as follows,-
Supposing a vessel placed. at any desired point of a bridge is filled up to a pre-
determined level with water, mercury, petroleum, or other liquid. This vessel is
connected by a tube with stationary vessel B in any desired position off the bridge.
In accordance with the well-known physical law the result will be, that, whatever
may be the deflection of the girder at the point where the movable vessel is placed,
the liquid will always rise to the same level in both the vessels and therefore any
depression of the level of liquid in the movable vessel which follows the vibrations
of the girder will bring about a corresponding depression of the level in the vessel B
which is stationary, and should on the other hand the water-level in the movable
vessel rise, it will correspondingly rise in B also.
The invention will be best understood by reference to the accompanying drawings
in which
Fig. 1 represents a complete apparatus for testing structures having say two
girders (neither of the two vessels placed on the girders being shown, however) and

page_text: Fig. 2 is a section on line 5-6 Fig. 1.°
Fig. 2B
a cross section on line 1-2 Fig. 1.
Fig. 2 is a section on line 3-4 Fig. 2.
Fig. 2 is a view of the right hand side of Fig. 2° illustrating the motion of the
cylinder.
Fig. 3 is a plan of the upper pencil or marker-carrying frame.
Fig. 4 is a plan of the two stationary vessels located off the bridge or structure
to be tested.
Fig. 5 shows a contact breaking device of which Fig. 6 is a side elevation.
Fig. 7 shows the open cylinder of this device.
Fig. 8 is another contact breaking or switch device acting jointly with the
first.
In this figure the wheel 11 keyed on to the shaft which supports the wheel 12 is
shown eccentrically, so as to expose the various parts of the switch device.
Fig. 9 is a section of the support of two stationary cylinders of which Fig. 10 is
a detail view.
Fig. 11 represents the whole circuit including the electro-magnet which operates
the drum and the two contact-breaking or switch devices which are actuated by
means of clockwork.
Fig. 12 shows a portion of the record sheet which receives the markings or
impressions of the markers or styles.
The arrangement represented in these figures is assumed to comprise two
stationary and two movable vessels, though it will be understood that testing plants
may be similarly arranged with any suitable number of vessels according to the
number of girders or parts there are in the structure to be tested.
Two floats & placed in the vessels B B' follow all the variations of level taking
place in these vessels, and this displacement of the floats is communicated to two
pencil-carrying arms through the medium of levers / l'.
The stationary and the movable vessels preferably differ in size since it.may be
desirable either to increase the extent of the variations of the water-level in say the
vessel B which are caused by the variations of level in the movable vessel which
result is obtained by reducing the horizontal dimensions of the vessel B, that is, the
diameter of B if B is cylindrical or to diminish the extent of these variations of
level in B, in which case the horizontal dimension of B viz. the diameter if B is
cylindrical, should be larger than that of the movable vessel. Each float is
connected to one end of the corresponding lever, the other end of which carries a
counterweight which counterbalances the weight of the float.
Any displacement of one of the floats will result in an oscillating motion of the
corresponding pencil or marker pivotted at o or o', the amplitude of such oscillation
depending on the amount of displacement of the float.
A drum C adapted for uniform rotary motion is arranged in front of the pencil
carriers ss hereinafter termed styles or markers inscribing on the paper carried
along by the drum a line indicating the oscillations caused by the displacement of
the floats. This drum is rotated by means of an electro-magnet E which as it
attracts the armature G secured to the lever F shifts the pawl arm H to the left
of Figs. 1 and 2c which arm H at each attraction of G causes the ratchet wheel. I
to move to the extent of one tooth. By means of the worm J and worm-wheel K
the rotary. motion of the wheel I is transmitted to the drum C. To obtain regular
motion at different rates of speed varying according to the nature of the tests to be
performed it, is therefore, sufficient to control the electro-magnet.by means of an
automatic switch device adapted to produce a given uniform.number of interruptions
of current in a given unit of time, during the whole time of the test, such device
being combined with another device or commutator by means of which the number

page_text: of interruptions per unit of time may be arranged to vary after the completion of
one test and before a fresh operation is commenced or even if necessary in the
course of the same testing operation.
The two switch devices or commutators employed for this purpose are described
further on. The band or strip of paper which is to receive the marks of the styles
issues from a roller M' arranged at the lower part of the apparatus and is wound
on the drum C after having received the markings.
The styles or markers s and are operated by the floats and one additional
style or markers" is so arranged that a reciprocating motion can be imparted to it
at will by means of a vibrator T so that any suitable number of short strokes will
be produced on the paper, which subsequently enables the markings of the styles
and produced during the various tests to be distinguished from each other, and a
number of equi-distant styles or markers are moreover arranged above the drum C
so as to draw a series of parallel and equi-distant lines on the paper. These styles
are mounted in a frame (Fig. 3) divided into two parts which may be moved closer
together or farther apart as required thereby enabling at the beginning of a test
the registering styles or markers s s to be brought into contact with two of the
parallel lines traced by the said equidistant styles.
To
It may be useful to remove the registering styles or markers away from the
drum C for a time, to avoid for example the registration of oscillations due to other
causes than those which it is the object of the test to ascertain; say if a bridge be
tested the markers may be moved away during the passage of a train as the
trepidations caused thereby are not within the scope of the intended test.
enable the markers to be thus shifted the two arms which carry them are placed in
front of the frame P Q R secured upon the shaft S so that the rotation of this
shaft carries the frame around and the cross-piece R by pressing upon the arms & ³¹
moves them and the markers carried thereby away from the drum. The rotary
motion of the shaft S is obtained by means of the electro-magnet T' arranged in
the following manner,-A permanent magnet T" of ordinary horse-shoe shape
surrounds a bobbin or coil within which is a soft iron core the end of which is
situated between the two poles of the magnet. So long as no current passes
through the coil the soft iron core will not move out of the position which it has
occupied at the preceding test, but as soon as a current is sent through the coil in
a given direction, this will generate a magnetic pole at the end of the soft iron
core which is opposite to the poles of the magnet and therefore this end of the core
will be attracted by the pole of the magnet of opposite polarity, the result of this
movement being a rotary movement of the shaft S which then carries the
frame P Q R round and moves the markers away from the drum as stated.
To move away again the soft iron core from the pole of the magnet which has
attracted it, it is only necessary to change the direction of the current the passage
of which in all cases only lasts an instant.
The amplitude or extent of the oscillations of each registering marker or style s st
while depending on the height of rise or fall of the girder or part to be tested and
of the difference between the respective surfaces of the stationary and movable
vessels, also depends on the situation of the point of attachment of the corresponding
float to the lever lor. To vary such amplitude therefore as required the point
of attachment of the float to the said lever may be shifted and to enable the cord
connecting the float to the lever to remain vertical it is necessary that the
vessels B B' should be capable of displacement. For this purpose the plates 1
and 2 upon which the test-vessels are erected may be moved in a direction parallel
to the apparatus in a groove provided in the piece 3 (Fig. 4) below. The two
plates are secured in the desired position by means of nuts and screws 4 and 5.
The apparatus herein described being operated by electricity may be placed at
any convenient distance from the structure to be tested so that a number of them
may be centred in one spot and operated by one man provided always that the
various electrical circuits are all connected to such centre of operation,

page_text: Maon apparatus comprises three circuits,
Circuit No. 1 including the switch device which operates the style s¹¹ or numbering
style.
Circuit No. 2 serving to move the two registering styles away from the cylinder
when required, and
Circuit No. 3 imparting motion to the drum und established in the following
manner,
The battery 6 (Fig. 11) is electrically connected to the binding-post 9 (Fig. 8)
and the current cannot pass into the plate 7 except when this plate is in contact
with the said binding-post 9 which it is only at the precise moment when one of the
teeth of the wheel 11 presses the piece 10 with its upper part. The instant this
takes place the current comes up to the plate 8 whence it can only pass on to the
binding-post 14 if 8 and 14 are in electrical contact. It will therefore be seen that
the current can only pass through the apparatus shown in Fig. 8 when the two
contact plates are actually in contact with the binding-posts, and they can never be
so for more than an instant although they can move into contact as often and in as
quick succession as may be desired, all that is necessary to do this being to increase
the number of the teeth of the wheels 11 and 12. These wheels rotate uniformly
under the action of clockwork arranged at 15 and which also operates the drum or
barrel 16.
This drum or barrel is formed of four conducting rings a a¹ all all and four non-
conducting rings which however are provided with conducting portions in numbers
increasing at a ratio of 1. 3. 6, the last being a conductor of electricity throughout.
On leaving the binding-post 14 the current passes into the plate 17 thence into the
electromagnet E, whenever the plate 18 comes into contact with one of the
conducting parts of the non-conducting rings cccc. It will thus be seen that
according to the position occupied by the plates 17 and 18 in relation to the barrel
or drum 16, the current may pass through the electro-magnet, once, three times,
6 times, or any number of times equal to the number of teeth on the wheel 11
during one complete revolution of the said drum 16. The cylinder C therefore
will move at a variable rate of speed according to the position of the plates 17
and 18.
Figure 12 conveys an idea of the appearance of the record-sheet after the various
styles or markers have left their marks thereon.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is,
1. In apparatus for indicating and registering the vibration or deflection of
bridges and metal structures generally vessels connected with each other and filled
with liquid those at one end being arranged to follow the deflections of the girders
beams or parts to be tested while those at the other end serve for transmitting the
movements of the former to registering markers or styles through the medium of
the liquid contained in them and floats supported on the liquid.
2. In apparatus for indicating and registering the vibration or deflection of
bridges and metal structures generally a drum carrying material adapted to receive
the impressions or markings of the styles or markers and to be revolved in a
uniform manner by means of an electro-magnet operated by a switch or commutator
and capable of varying the speed of rotation of the drum at the operator's will.
3. In apparatus for indicating and registering the vibration or deflection of
bridges and metal structures generally a switch or commutator included in the
circuit which actuates the electro-magnet of the drum carrying the material to
receive the markings the drum or barrel of the said commutator being divided into
conducting and non-conducting sectors and capable of receiving continuous rotary
motion from suitable clockwork the current collectors of the commutator being
adapted to move in a direction parallel to the said drum or barrel and to be so

page_text: controlled as to produce a greater or less number of interruptions of current during
one revolution of the drum substantially as described.
4. In apparatus for indicating and registering the vibration or deflection of
bridges and metal structures generally numbering and guiding styles or markers
the former of which may be operated by a vibrator set in motion at the operator's
will so as to number or count the various curves taken down during the successive
tests.
Deted this 12th dex of January 1893
W. P. THOMPSON & BOULT,
Agents for the Applicant.