IMPROVEMENTS IN COAL CUTTING MACHINES, PART OF WHICH IMPROVEMENTS RECIPROCATING HYDRAULIC ENGINES GENERALLY
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by Paget Higgs at the Office of
the Commissioners of Patents, with his Petition, on the 22nd
September 1874.
I, PAGET HIGGS, of Southampton Buildings, in the County of Middle-
sex, and of Cardiff, in the County of Glamorgan, Civil Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
COAL CUTTING MACHINES, PART OF WHICH IMPROVEMENTS
RECIPROCATING HYDRAULIC ENGINES GENERALLY," to be as follows:-
IS APPLICABLE TO
This Invention relates chiefly to coal cutting machinery wherein
hydraulic power is employed to force forward a piston or ram carrying a
cutter bar, wherein are placed removeable cutting points or tools. The
return stroke of the piston or ram I effect by the resilience of a spring,
or of a volume of atmospheric air which has been compressed by the
forward stroke of the piston itself, the compression chamber being a
portion of the cylinder, or an auxiliary chamber attached thereto, cither
or combined.
I regulate the return air pressure in amount by increasing or
decreasing the capacity of the auxiliary chamber (which chamber may
be of constant or of variable capacity), or by increasing or decreasing the
area of piston acted upon by the compressed air, which is effected by

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decreasing or increasing the diameter of the piston rod, the piston rod
being hollow and forming the socket wherein is inserted the cutter bar.
When the piston or ram has completed its forward stroke, which in the
case of the coal cutter is also the cutting stroke, I cause the return
stroke to be consequent by the force stored up in the compressed air or
spring upon the release of the water from the back of the piston by
means of a valve manipulated by hand or automatically as a slide valve
with well-known mechanical adjuncts.
I further prefer to construct this coal cutting machine so that it may
be self-containing, that is to say, I so arrange that the pump which
supplys the hydraulic power for forcing the piston forward shall be a
continuation of the cylinder, separated therefrom by the necessary
diaphragms and joined thereto by proper passages, as in ordinary hand-
power hydraulic machines. But I may cause the hydraulic power to be
derived from separate pumps connected to the said cylinder either
directly or from an accumulator, the accumulator being preferably of
the construction herein-after described.
I do not limit myself to the use of hydraulic power to cause the for-
ward stroke of the piston, but I may use therefor steam or compressed
air, returning the piston as herein-before described and regulating its
return pressure by the methods also as described.
The accumulator I would prefer in same cases to use differs from
ordinary accumulators in the following particulars :-Whereas in
ordinary accumulators the downward pressure of a weight maintains the
hydraulic pressure, I substitute the pressure from the ram of a hydraulic a
press or system so that the accumulator may be horizontal or vertical in
arrangement as may be required. The pressure upon the plunger of the
said hydraulic press or system I maintain by means either of a weight
or of a constant head of water, or of the backward pressure of the
plunger into a chamber or cylinder containing air, which is subjected to a
compression and rendered resilient by such backward pressure, the
amount of compression being limited and regulated by an auxiliary
chamber, as herein-before described.