IMPROVEMENTS IN PRESSURE-GAUGES
Year: 1887

page_text: We, RICHARD GRadenwitz and ERDMANN AUGUST TAENZER of Brandenburgstrasse,
Berlin, in the German Empire, Engineers do hereby declare the nature of said inven-
tion for IMPROVEMENTS IN PRESSURE-GAUGES" and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:
This invention has reference to mechanism for tell tale pressure gauges by which
incorrectness of action may be indicated. It may be employed both for ordinary
pressure gauges and for testing Bourdon tubes.
For this purpose two or more Bourdon tubes are simultaneously exposed to the
pressure to be gauged each acting independently on a separate pointer indicating on
a separate scale so that when the respective pointers differ in the amount of pressure
they indicate it may be known that one or more of the said Bourdon tubes is or are
faulty.
In previously constructed apparatus of this kind two springs have been employed
under similar conditions each acting on a separate pointer, but the travel of the
pointers is the same. In the present invention the one pointer has a difference of
travel or stroke over the other or others, the object being to attain great exactness. in
the working of the testing mechanism.
The accompanying drawing represents a pressure gauge fitted with the mechanism
of our invention, and having two of the said Bourdon tubes, Fig. 1 being a
front elevation and Fig. 2 a horizontal section thereof. Fig. 3 shews a modified
arrangement of the pointers relatively to each other.
A, A', are two Bourdon tubes one of which is in connection with lever turning
on pivot g, through rod b, one end of being in the form of a toothed segment that
engages in the toothed wheel h fixed on the spindle d of the pointer i. In this way
the latter has transferred to it the movement of the tube A¹. The other Bourdon
tube A is also in connection with a lever e similar to f through rod c the toothed
end of e engaging and setting in motion toothed wheel h¹ fixed on a sleeve k turning
on the spindle d of the pointer i. At the other end of the sleeve k is fixed a toothed
wheel by which the movement of the toothed wheel h¹ is transferred to the spindle n.

page_text: mounted on pointer i the teeth of the same engaging toothed wheel m fixed on the
pointer spindle n. One part of the pointer i is shaped so as to form a scale p and on
the spindle n is fixed a pointer o which indicates on the scale p the movement of the
spring A.
In the modification shewn in Fig. 3 the scale p is arranged at a different part of
the pointer i, otherwise the mechanism is the same.
The
When the gauge is under pressure and the two Bourdon tubes A, A1, act correctly
the spring A will move and this movement be carried over to the pointer i through
rod 6 and lever f. Hereupon the spindle n of the pointer i also moves.
spring A performs simultaneously a similar movement to A' which is carried over to
the sleeve k through levere and toothed wheel h. Accordingly the sleeve k turns at
the same time as the pointer i moving the pointer o so far backward as the pointer i
moves forward, the two pointers thus moving together from a fixed position, their
relative positions being always the same.
When the two Bourdon tubes do not act correctly together the pointers deviate
from each other which deviation is the more pronounced by reason of the toothed
wheel multiplying the movement of the sleeve k on to the pointer o. As one of the
Bourdon tubes in order not to impair it-need only be brought into use when the
gauge is to be proved, the pressure may be admitted constantly to A¹ only whilst A
is shut off therefrom. In this case when the pointer i moves the pointer o will change
its position relative thereto, but so soon as the tubular spring A is exposed to the
pressure, the pointer will resume its former relative position to if both of the
tubular springs act correctly. The instrument may however be used as an ordinary
pressure gauge.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is:
In control mechanism for pressure gauges or manometers in which two or more
springs each act independently on a pointer the arrangement of the one pointer in
the other pointer and the arrangement of a toothed wheel connection which multiplies
the movement of one as compared with the other pointer substantially as described
and shewn.
Dated this 25th day of November 1887.