Improvements in Hydraulic Machinery.
Year: 1892

page_text: Date of Application, 9th Sept., 1892
Complete Specification Left, 5th June, 1893-Accepted, 8th July, 1893
PROVISIONAL SPECIFICATION.
Improvements in Hydraulic Machinery.
I, GEORGE MITCHELL of Bankhead, Dalswinton, in the County of Dumfries,
Engineer, do hereby declare the nature of my invention to be as follows:-
:-
My invention relates to hydraulic machinery and has for its object 1stly the
arrangement of special means for balancing or moving the main ram of a hydraulic
press or the like so that the balancing or supplementary ram moving device, adds
to the power of the main ram instead of detracting therefrom as is the case with
balancing devices as now fitted and 2nd the arrangement of cup leathers and gland
in a novel form whereby great efficiency durability and accessibility are obtained.
My invention consists firstly in the arrangement of a balance cylinder at the
back of the main hydraulic cylinder in which a supplementary piston is arranged
to work having cupleathers or other packing arranged for both directions of
working. This piston is connected by a piston rod of smaller diameter than the
piston, to the main ram; the piston rod passing through a gland or glands situated
between the two cylinders.
A hole is provided in the piston rod down its centre from end to end which
affords communication between the main cylinder and the back of the supplementary
cylinder, or equivalently the connection may be formed by means of a pipe. The
annular area around the rod of the supplementary piston on the front side forms
the effective area for balancing or drawing the ram backward into its cylinder.
When this is being effected the front side of the supplementary piston is exposed
to the pressure of the supply main while the main cylinder and back of the
When these
supplementary cylinder are in communication with the exhaust.
conditions are reversed and the ram is being forced out it will be clearly seen that
the area acted upon by the pressure is the full area of the main ram plus the area of
the supplementary piston minus the area of the piston rod, and thus a greater
pressure is exerted than that due to the area of the main ram alone.
The second part of my invention consists in the special arrangement of gland and
cup leather in a novel form. I place at the bottom of the gland recess a ring
having a part of both inside and outside surface formed so as to receive a cup
leather saddle fashion across one end of the said ring. The leather and lower part
of the ring thus fill up the gland space for a certain distance of length between the
ram and the cylinder. The leather is maintained in place by a gland like ring
having a concave face to fit the top of the leather which fits into the annular space
and has a flange or other equivalent device, which forms a means of attachment by
bolts or otherwise to the cylinder head.
I find that this form of gland keeps water tight and lasts longer than the usual
form of leather packing.
I also provide means for the catching of water which has escaped past the cup
leather. This consists of a circular groove arranged around the internal surface
of the gland and holes communicating therefrom to a similar groove arranged in
the main cylinder opposite to the said holes, and a drain pipe is fitted thereto to
carry off the water.
It will thus be seen that the escape water is arrested on its passage, from the cup
leather before it reaches the end of the retaining ring or gland.
Dated this 9th day of September 1892.
FELL & WILDING,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.

page_text: '
COMPLETE SPECIFICATION.
Improvements in Hydraulic Machinery.
I GEORGE MITCHELL-late of Bankhead Dalswinton, in the County of Dumfries
now of 47 Victoria Street Westminster Engineer 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 hydraulic machinery and has for its object firstly the
arrangement of special means of balancing or moving the main ram of an hydraulic
press or the like so that the balancing or supplementary ram moving device adds
to the power of the main ram instead of detracting therefrom as is the case with
balancing devices as now fitted. And secondly the arrangement of cup leathers
and gland in a novel form whereby greater efficiency durability and accessibility
are obtained.
And in order that my invention may be fully understood and readily carried into
effect I will describe the same with accompanying drawing, reference being had to
the letters and figures marked thereon.
Figure 1 is a sectional elevation of an hydraulic cylinder and ram as fitted with
the balancing or supplementary ram moving device and improved arrangement of
cup leather and gland.
My invention consists firstly in the arrangement of the balance cylinder a at the
back of the main hydraulic cylinder 6 in which a supplementary piston c is.arranged
to. work having cup leathers or other packing arranged as shown on drawing for
working under pressure from either side. The piston e is connected by a piston
rod d of smaller diameter than the piston e to the main rame the piston rod d
passing through a gland or glands situated between the two cylinders and which
will work hydraulically tight from either side practically as shown on the
accompanying drawing.
A hole d is provided in the piston rod down its centre from end to end or so
close to the end of, rod next main ram, as that the orifice g will always be within
the main hydraulic cylinder b and which affords communication between the main
cylinder band the back of the supplementary cylinder and piston c or equivalently
the connection may be formed by means of a pipe.
The annular area around the rod of the supplementary piston on the front
side forms the effective area for balancing or drawing the main ram e back into its
cylinder.
When this is being effected the front side of the supplementary piston c is
exposed to the pressure from the hydraulic main through the inlet branch while
the main cylinder and back of the supplementary cylinder through the hole d¹ are
in communication with the exhaust.
When these conditions are reversed and the main ram is being forced out it will
be clearly seen that the area acted upon by the pressure is the full area of the
main ram plus the area of the supplementary piston minus the area of the piston
rod and thus a greater pressure is exerted than that due to the area of the main
ram alone.
The second part of my invention consists in the special arrangement of gland
and cup leather in a novel form as will be seen in the arrangement Figure I
accompanying drawing and Figure 2 enlarged section and elevation.
I place at the bottom of the gland recess a neck ring as shown, formed so
as to receive a U cup leather saddle. fashion, the convex portion has a series of
projections of the form of and in which the cup leather rests and between
which the hydraulic liquid freely circulates, passing to the inside of the cup
leather by means of the holes from the main cylinder; the cross holes m
communicating between the spaces materially assist in retaining a uniform pressure
inside the cup leather and keeping it tight at low pressures. The leather is

page_text: maintained in place by a gland-like ring a having a concave face to fit the top
of the cup leather, which fits into the annular space and has a flange or other
equivalent device which forms a means of attachment by bolts or otherwise to
the cylinder head.
I also provide means for catching the hydraulic liquid which has escaped past
the cup leather.
This consists of a circular groove arranged round the internal surface of the
gland and holes o communicating therefrom to, a similar groove arranged on
the outer surface of the gland and in the main cylinder opposite to the said holes
and a draw pipe p is fitted as shown to carry off the liquid.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1st. The simple, novel, and economical application of a balancing or supplementary
cylinder and piston for withdrawing hydraulic rams, which when in operation
adds to the effective pressure on the main ram.
2nd. By means of the hole through the supplementary piston rod connecting the
main cylinder with the outer end of the supplementary cylinder reducing the
number of working parts, valves pipes and connections and thereby lessening
the risks of breakdowns and leakage in working.
3rd. The concave and convex gland rings with the projections as shown keeping
the cup leather steadily in place and preventing shrinkage.
4th. The holes through the convex ring as shewn allowing free circulation and
immediate pressure evenly within the cup leather.
5th. Grooves as arranged to intercept the liquid escaping past the cup leather
and thereby prevent it coming in contact with other liquid or the material being
pressed.
Deted this Third day of June 1893.
GEO. MITCHELL,