Year: 1898

page_text: HENRY CAPEL LOFFT HOLDEN, Major, Royal Artillery, Royal Arsenal, Wool-
wich, S.E., do hereby declare the nature of this invention to be as follows:-
My invention relates to an improved pressure gauge, for use in guns, which is
not only more accurate in its results but also more convenient to use than the
ordinary pressure gauge, generally known as the crusher gauge, in which the
pressure is measured by the compression of a cylinder of copper or other
metal.
According to my invention a steel piston of suitable dimensions is accurately
fitted to an opening bored in one end of a steel box inside which is a spring of
volute spiral or other form and of suitable strength and range of compression
for the purpose in hand. The piston bears upon the top of the spring in such a
manner that any pressure applied upon the piston tends to compress the spring.
The base of the spring rests upon a disc of metal having a tubular portion in the
interior of the spring; through this tubular portion slides, friction tight, a steel
index piece by means of which the compression of the spring is registered. In
order to use the gauge the spring is placed upon the disc and the index piece
adjusted so that it is flush with the top of the spring. The height of the spring
or index and disc is then measured with a micrometer; the whole is then placed
in the steel box, inserted in the gun and subjected to the pressure which it is
require to measure. The pressure acting upon the piston compresses the spring
and forces the index piece into the tubular portion of the disc to the exact extent
that the spring is compressed. On the pressure being relieved from the piston
the spring returns to its former length, but the index remains and forms a register
of the compression of the spring. When the box is opened the disc is taken out
and the height to the top of the index is again measured; the difference between
this measurement and the former one gives the compression of the spring. The
pressure per square inch is obtained from the area of the piston employed and the
calibration of the spring. The piston should have a gascheck to prevent any
escape past it into the box containing the spring vitiating the record.
It is obvious that with the above gauge errors due to variation in the metal
cylinders are avoided by the same spring being used over and over again, its
calibration being checked from time to time.

page_text: An Improved Pressure Gauge for Ordnance.
HENRY CAPEL LOFFT HOLDEN, Major, Royal Artillery, Royal Arsenal, Wool-
wich, 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 an improved form of pressure gauge for use in guns,
which is not only more convenient in use, but is also more accurate than the
ordinary pressure gauge, or crusher gauge as it is usually termed, wherein the
pressure is measured by the compression of a copper cylinder.
According to my invention a steel piston of suitable dimensions is accurately
fitted to an opening bored in the end of a steel box inside which is a spring of
volute spiral or other form, and of suitable strength and range of compression
for the purpose in hand. The piston bears upon the top of the spring in such
manner that any pressure applied upon the piston tends to compress the spring
The base of the spring rests upon a dise of metal having a tubular portion in the
interior of the spring; through this tubular portion slides friction tight, a steel
index piece by means of which the compression of the spring is registered. In
order to use the gauge the spring is placed upon the disc and the index piece
adjusted so that it is flush with the top of the spring; the height of the two
is then measured with a micrometer; the whole is then placed in the steel box
and subjected to the pressure which it is required to measure.
The pressure
acting upon the piston compresses the spring and forces the index piece into
the tubular portion of the disc to the exact extent that the spring is compressed.
On the pressure being relieved from the piston the spring returns to its former
length but the index remains and forms a register of the compression of the
spring. When the box is opened the disc is taken out and the height to the
top of the index again measured; the difference between this measurement and
the former one gives the compression of the spring. The pressure per square
inch is obtained from a knowledge of the area of the piston employed and the
calibration of the spring.
Referring now to the accompanying drawings. Fig. 1 shews in section and
elevation the gauge complete. Fig. 2 shows a detail of the registering apparatus:
A steel box B has a screwed cap A by means of which is it closed; through the
cap is bored a hole in which the piston C is an accurate fit, the piston is moreover
provided with a gascheck, D, made in accordance with my Patent of 1898
No. 10442, in order to ensure that no gas pass the piston into the gauge; the
piston C has an enlarged head at its inner end bearing upon the volute spring E.
This spring rests upon a piece F in the split stem H of which a small rod G is
held by friction, see Fig. 2. The rod G before use is adjusted so as to be level
with the top of the spring E. In the gun when the pressure of the gases comes
upon the piston C this latter compresses the spring E and thus the rod G is forced
into the piece F to the exact extent that the spring is compressed, but on the
pressure being relieved the spring extends again, whilst the rod remains in
the piece F. The distance that the rod G has been pressed into F is a measure
of the compression of the spring; and from this compression it is easy, as has
already been explained to ascertain the maximum pressure to which the gauge has
been subjected.

page_text: Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is:-
(1) In a pressure gauge for ordnance the combination of piston, spring and
index substantially as described and for the purposes set forth.
(2) The pressure gauge substantially as described.
Dated this 14th day of February 1899.
H. C. L. HOLDEN,
G. F. Redfern & Co.,
Major, R.A.
4, South Street, Finsbury, London, Agents for the Applicant.