IMPROVEMENTS IN PRESSES FOR COMPRESSING COTTON, JUTE, AND OTHER MATERIALS
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by William Thompson Mann at the
Office of the Commissioners of Patents, with his Petition, on the
28th October 1874.-A communication from abroad by James
Watson, of Calcutta.
I, WILLIAM THOMPSON MANN, of the Firm of Fawcett, Preston, and
Company, of Liverpool, in the County of Lancaster, Engineers, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
PRESSES FOR COMPRESSING COTTON, JUTE, AND OTHER MATERIALS," to be as
follows:-
This Invention has reference more particularly to the presses described
in the Specification of Letters Patent granted to James Watson, bearing
date the 28th day of October 1869, No. 3123. The said Specification
described a blocking apparatus composed of a gridiron frame or of a solid
block made to slide into the press between the upper surface of a lower
66 follower or platform and the under side of the bale of material under
treatment. The gridiron frame or block was moved into and out of the
press at the proper times by means of racks and pinions actuated by
hand wheels.
"
Now the object of one part of the present Invention is to make the
gridiron frame self-acting. For this purpose chains are secured to the

page_text: bottom of the lower follower, and after going under or round grooved
rollers pass over grooved wheels. These wheels run loosely on the pinion
shaft of the gridiron frame, but can be made by means of clutches
worked by the attendant, to turn with the shaft when required. They
are provided with whelps or similar devices to ensure the grip of the
chains thereon. The ends of the chains carry small balance weights to
take up the slack when the lower follower descends. On the said pinion
shaft two other similar wheels are keyed, over which chains provided with
weights pass.
The action is as follows:-When the lower rams rise and lift the
lower follower the chains attached thereto cause the grooved wheels
over which they pass to rotate, and the clutches being engaged, similar
rotation is imparted to the pinion shaft and to the other grooved wheels
thereon, the weights attached to the latter being thereby raised. When
the up stroke of the lower ram is completed the clutches are disengaged,
and the weights being then free descend and thus cause their grooved
wheels to rotate together with the pinions on the same shaft, and as these
pinions gear into the grid racks the grid is moved into its place below
the bale, which is now ready to receive the final pressure by means of the
upper rams. After this pressure has been completed the grid is shot
back by hand. The same object may be effected by means of two small
hydraulic cylinders; these may be bolted to the frame of the press, and
are double acting, that is to say, provided with ordinary means of applying
pressure to either side of their pistons or rams, and of thus forcing their
rods into or out of the cylinders. The cylinders have valves of the usual
kind to admit the water under pressure to either end, and may be worked
by means of tappets attached to the top and lower rams.
Another part of the Invention consists of a self-acting relief valve.
This is similar to an ordinary safety valve, and has a lever to engage with
a stop or washer on a bar attached to the lower rams of the press.
When these rams have attained their proper lift the stop or washer
raises the lever, and the water under pressure then passes away
through the valve to waste or to return instead of passing into the lower
cylinders. When the rams descend a weight on the lever causes the
valve to close.
Another part of the Invention consists of a check safety valve. A
lever safety valve of the ordinary construction is employed, but as under
the heavy pressures used with hydraulic machinery the recoil of the water

page_text: due to the closing and opening of the valve causes the valve to jump and
quickly wear out, there is in order to prevent this jumping a box fixed
at a suitable distance in which a small plunger works loaded to the exact
pressure required. The lever safety valve is loaded to such an excess of
pressure that it will not rise until a certain portion of the load on its lever
is lifted or overcome by means of the plunger. The plunger rests on the
body of water, and is therefore not subject to recoils, but simply rises
with the excess of pressure, and on the excess being removed descends
without shock; the extra load on the safety valve prevents this valve
rising unless aided by the plunger, all jumping and recoil being thus
avoided.
If preferred, the plunger may be fitted to work in the same box, and bo
loaded by the same lever as the safety valve itself. The action will be
the same as above described, the plunger being loaded to the required
pressure, and on this being exceeded it rises and relieves the safety valve
of the weight in excess.