Improvements in Apparatus for Indication of Fluid Pressure, and for Adjustment while at Work.
Year: 1893

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus for Indication of Fluid Pressure, and
for Adjustment while at Work.
I, AUGUST BODENSTEDT Junior of Kaiserstrasse, Bremen, 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:—
This invention refers to a new arrangement according to which the fluid pressure;
say steam in a boiler, acting upon a piston which directly or indirectly compresses
an adjustable spiral or volute spring, is indicated upon a scale by suitable inter-
vening mechanism.
By this arrangement it becomes possible to determine the pressure scale beforehand
by calculation; because the tension of the spring to be used can be fixed upon.
Any irregularities in the material or in the adjustment of the spring by long use
or wear of the spring can be regulated by moving a sliding piece arranged in the
central inner part of the spring.
The pressure indicator thus constructed hence works on the basis of perfectly
known and calculable relations while also possessing the advantage of adjustability
at any time during work.
Fig. 1 is a vertical section through the apparatus and Fig. 2 an end view with
part of the outer casing removed.
Figs. 3 and 4 refer to a modification.
As shewn in Figs. 1 and 2 the apparatus consists of a pressure cylinder 6 which
by means of screw union c d is connected fluid tight to the steam boiler or other
source of power directly or to a pipe leading thereto e is a piston which is ground
in to work fluid tight in the cylinder without need of packing even by high pressure;
in special cases however the piston may be provided with annular grooves for pack-
ing or metallic packing rings. The piston e terminates in an upper flange or
saucer shaped disc g upon which rests the spring f, of circular or other section
material. The cylinder is provided with an oval or rectangular plate a having a
flange for receiving a bell or casing of glass or metal. On the plate a are mounted
two posts or columns h screw threaded at each end for fixing to the plate a and
connecting with a cross plate i, which forms abutment for the spring and serves
to put the spring in tension. On the middle of the plunger flange g is mounted a
column k which passes through the cross plate and terminates in a fork that
receives a roller upon which rests one arm m of the lever m n having its fulcrum
The arm n ends in a pointer which indicates on the segment scale p that is
divided and marked according to the steam pressure. On the short arm m is
mounted a sliding weight r for balancing the long arm n. The spring is a spiral
spring coned at each end and cylindrical in the middle, where the socket s that
works on the column k has a half round helical groove corresponding with the
cylindrical spring coils resting therein. So far as these coils bed in the socket s
they are quite held thereby and therefore cannot act with the other coils of the
spring, that is to say the power of the spring is only measured by the number of
free coils. The further the socket s is screwed down the more of the held part of
the spring will be made free and the strength inherent in this released part will
assert itself. By screwing the socket s more or less up or down the power of the
spring can be exactly adjusted and to a part of a grain. The spring is thus
rendered adjustable without removing the apparatus from its place or taking it to
pieces.
at o.
The bell or casing is only for protection and can be easily taken off by the person

page_text: The guide column k may be marked with incised divisions the lines of which may
be annular or helical or consist of single arrow lines. Similarly the end face of
the socket s may also be marked with radial lines provided with letter indications
so that from the zero point the extent of lowering or raising may be read off.
Obviously the double coned spring may be replaced by springs of other form as
for instance shewn in Fig. 3 where a flat volute spring fis used the tension of which
can be regulated by, for instance, raising or lowering the crossplate i through which
the posts pass freely being fitted with top and bottom nuts.
The mode of action is as follows. The pressure in the boiler or other vessel acts
directly on the piston e and through it on the spring f so that the piston will be
raised more or less, while a cessation of pressure will cause the piston to go back
into its original position. The post k following the motions of the piston will by its
roller act on the short lever arm m so as to swing the pointer to indicate on the
scale p the height of the steam pressure.
The transmission of the rising motion of the column k is in this case direct by the
roller and lever m n but may also be indirect by tooth wheels or friction pulleys
or other suitable means.
If the permissible maximum pressure of the steam should be exceeded the surplus
will be relieved by the small hole o¹ in the piston when it coincides with the hole o"
in the cylinder 6 and whereby a bell may also be set ringing. In this way a sort of
control is established over the safety valves, which constitutes a valuable collateral
advantage of the invention.
Should nevertheless the rise of pressure be so great that the piston e rises still
further and moves the pointer beyond the scale indications then the auxiliary hand u
Fig. 1 will serve to indicate such pressure by reason of the arm n coming in contact
with its upper part.
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 :-
1. Apparatus for indicating and adjusting the pressure of a fluid (steam, gas or
liquid) which directly or indirectly acts upon a double coned spiral spring adjustable
in itself (or upon the adjustable volute spring) in such manner that the pressure is
by suitable intermediate machine element indicated visibly on a scale.
2. An indicating apparatus acting as firstly claimed having an adjustable spring
resting on a piston which by the pressure of the fluid is moved up and down and
thereby through intermediate machine elements such as the post and the roller l
moves the pressure gauge pointer.
3. In an indicator as secondly claimed an adjustable double coned spiral spring,
having a central cylindrical portion which coils in the helical grooves of a piece s
that can be screwed up and down for the purpose of fixing or freeing the
cylindrical coils more or less according as the power of the spring is to be increased
or decreased.
4. In an indicator as secondly claimed a piston e having a hole o' which is so
arranged that by excess of fluid pressure it coincides with the hole o" in the
cylinder for the purpose of relieving the pressure and if desired sounds a bell.
Dated this 20th day of October 1893.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.