IMPROVE- to be as MENTS IN APPARATUS FOR TESTING PRESSURE AND VACUUM GAUGES follows:
Year: 1884

page_text: I JOHN JACKSON of 33 Southampton Buildings Holborn in the County of
Middlesex Engineer do hereby declare the nature of my Invention for "IMPROVE-
to be as
MENTS IN APPARATUS FOR TESTING PRESSURE AND VACUUM GAUGES
follows:-
"
Hitherto it has been found extremely difficult to make testing apparatus to
work to a sufficiently high pressure.
Now the object of my invention is to construct a simple and effective apparatus
whereby steam hydraulic and vacuum gauges may be tested up to a pressure of
say twenty tons or more.
This I effect in the following manner-I cast the body of the apparatus (hereafter
termed "the pump ")-in gun metal, and bore two horizontal channels therein;—
in the lower one whereof a solid steel plunger works while the upper one serves to
feed the water to the gauge to be tested.
Such channels, communicate with each other by means of a vertical passage
drilled through the pump at the feed end.
The steel plunger is worked by means of a screw shaft having a V thread formed
thereon while mounted on such shaft is a guide which works in a slotted guide
plate This guide serves to control the action of the plunger.
The pump
is fitted into a suitable carriage which is screwed to a bed plate.
Mounted on the end of the screw shaft is a wheel which forms the motor of the
plunger.
The travel of this wheel is controlled by a semi circular cap which is fitted over
the wheel in a recess or groove formed therein for that purpose and is secured by
means of screw nuts.
Such semi circular cap has a convenient orifice formed therein to allow of the
lubrication of the wheel when requisite.
The pump is provided with two nozzles in the ordinary manner each furnished
with a screw cap so as to allow of the standard and test gauge being fitted thereto
I fit such nozzles with copper washers so as to make perfect joints at the couplings.
The apparatus is fed by means of a screw seated or other suitable cock constructed
to provide for the high pressure to which the apparatus is worked.

page_text: In order to reduce the friction I make the plunger with a head and neck, the
head corresponding in size to the size of the bore while the neck is smaller thus
producing friction only with the head, and I pack such plunger in the ordinary
manner.
At the mouth of the bore in which the plunger works I provide a socket piece
fitted with a perforated cap through which the plunger works.
The operation of my improved test apparatus is as follows:-
Having fixed the test gauge and trial gauge on their respective nozzles I
the feed cock and turn the wheel mounted on the screw shaft.
open
By so doing the plunger gradually recedes thereby creating a vacuum and
drawing the water or other liquid into the body of the apparatus.
When the plunger is drawn back to the farthest degree I turn off the Cock and
by a reverse motion of the wheel I obtain the required degree of pressure-such
pressure being readily obtainable up to 20 or 30 tons or more.
This will be found a great advantage in testing high pressure gauges.
My improved apparatus is equally applicable for testing vacuum gauges which is
done as follows
I open the feed cock and so allow the water to escape. I then again close the
cock and by reversing the action of the motor wheel the plunger again gradually
recedes and so produces a vacuum.
Dated this 25th dow of To 100A
ELT & Co.,
Agents for the Applicant,
33, Southampton Buildings, Holborn,
London.

page_text: I JOHN JACKSON of 33 Southampton Buildings Holborn in the County of
Middlesex Engineer do hereby declare the nature of my invention for IMPROVE-
MENTS IN APPARATUS FOR TESTING PRESSURE AND VACUUM GAUGES and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
Hitherto it has been found extremely difficult to make apparatus for testing
pressure and vacuum gauges work to a sufficiently high pressure.
Now the object of my invention is to construct a simple and effective apparatus
whereby such gauges may be readily tested up to a pressure of 20 tons or more.
Fig 1 shews a longitudinal section of such apparatus (a) is the body of the
apparatus which is cast solid with two nozzles (b). To these nozzles the test and
trial gauges are attached by screw couplings (c) which allow of such ganges being
adjusted in any convenient position while preferably the nozzles are fitted with
copper washers so as to make perfect joints at the couplings-lugs (d) are cast on
the body whereby it is fastened to a stand (e).
A boss is likewise cast thereon at its outer end-This boss is tapped and
threaded so as to form a feed port (f) through which the apparatus is charged
with liquid-To effect this when testing for high pressure a bent pipe or
syphon (g) is fitted thereto as shewn in Fig 1 but when testing for low or medium
pressure such pipe may be fitted with a cock (h) as shewn in the detail view
Fig 2-When not in use such feed port is closed by a screw cap (i) fitted with a
coned copper washer as seen in Fig 4 which shews a plan view of the apparatus.
I would here observe that I do not confine myself to this method of charging the
apparatus as I may utilize either of the nozzles to which the gauges are attached
for that purpose-A chamber (k) is formed in the body wherein a plunger (1)
works to and fro-This chamber terminates in a channel (m) leading direct to the
feed port (f) and communicating with the nozzles (6) through induction ports (n)-
The plunger is actuated by a screw shaft (j) mounted in a steel bushed guide (¹)
working in two slotted guide plates (³) and operated by a hand wheel (o)-A detail
view of one of such guide plates is seen at Fig 3-The front ends of these plates have
flanges (1) formed thereon to allow of their being bolted or otherwise fastened to
the body of the apparatus while at the back they are attached to a recessed
bearing (2) also provided with lugs (3) which carries a hand wheel (o)-A detail
view in elevation of such recessed bearing is shewn at Fig 6 and of the metal
strap presently mentioned at Fig 5-The wheel is kept in position by a metal
strap (p) provided with a lubricating orifice (9) and fitting over a fixed guide
nut (4) cast on the wheel-Such nut is threaded inside so that when the wheel is
operated a backward or forward travel is imparted to the screw shaft (j) while a
rotary motion only is given to the wheel (o).
By this arrangement a convenient carriage is formed for the plunger and shaft
and also for the guide and wheel at the same time that an extremely gradual but
very powerful and reciprocatory action is obtained when the apparatus is at work
thus obviating all risk of derangement or breakage.
In order to reduce the friction to a minimum I make the head of the plunger
short and to fit the bore of the chamber (k) accurately and I pack the same in the
ordinary manner.
An alternative arrangement of the channels (k-m) consists in placing them
parallel with each other and connecting them through the outer induction port.

page_text: The operation of the apparatus when testing for pressure is as follows:-Having
fixed the test and trial gauges on the nozzles open the feed pipe or cock attached
to the feed port and turn the hand wheel so as to cause the plunger to recede thus
drawing the liquid into the body of the apparatus-When the plunger is drawn
back as far as possible close the feed pipe or cock and turn the wheel in the reverse
direction thereby causing the plunger to advance and compress the liquid thus
forcing it into the gauges and obtaining the required indication.
When testing for vacuum screw the plunger as far as possible into the body close
the feed port with the screw cap turn the hand wheel so as to cause the plunger to
recede by doing which vacuum is produced and is indicated accurately upon the
gauges.
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° Fitting a testing apparatus for testing pressure and vacuum gauges with a
carriage constructed and arranged substantially in the manner and for the purposes
herein before specified and shewn.
2° The combination in such an apparatus of the plunger (1), screw shaft (j),
guide ('), and guide plates (j³) all constructed arranged and fitted substantially
in the manner and for the purposes herein before specified and shewn.
3° In such an apparatus mounting a hand wheel provided with a fixed guide
nut in a recessed bearing substantially in the manner and for the purposes
herein before specified and shewn.
4° Forming a feed port in the body of such an apparatus fitted with a screw cap
and communicating with the channel (m) and chamber (k). substantially as
herein before specified and shewn.
5° The improved construction of testing apparatus for testing pressure and
vacuum gauges as hereinbefore specified and shewn.
Dated this 25th day of October 1884.
'