CERTAIN IMPROVEMENTS IN REGULATING THE SUPPLY OR PRESSURE OF STEAM IN STEAM BREAKS
Year: 1875

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PROVISIONAL SPECIFICATION left by Thomas Pasfield at the Office
of the Commissioners of Patents, with his Petition, on the 5th
November 1875..
I, THOMAS PASFIELD, of Kates Hill, near Dudley, in the County of
Worcester, Engineer, do hereby declare the nature of my said Invention
for "CERTAIN IMPROVEMENTS IN REGULATING THE SUPPLY OR PRESSURE OF STEAM
IN STEAM BREAKS," to be as follows:-
My Invention is intended to be applied to steam breaks generally,
but is designed principally to those breaks where steam winding is much
used, as in coal pits; the new feature in my Invention being that by
my improved. valves the pressure of steam upon the break piston is
regulated at the pleasure of the breaksman.
.
My said improvements consist substantially in having the valve for
the admission of steam to the break cylinder and the valve for
exhausting the steam. from the same so arranged and connected
together by suitable rods or other gearing that whatever force is applied
to the steam supply valve to open it and allow steam to enter the
cylinder an equal force shall be applied to the other valve through

page_text: which the steam escapes, so that a pressure of steam just sufficient to
balance these valves is maintained in the break cylinder. These exhaust
and supply valves may be adjusted and regulated, as above described, by
any convenient arrangement of levers and springs, or by weights, or
other mechanical equivalents; but by preference I accomplish such
adjustment and regulation in the following manner (that is to say) :-
When the apparatus is in its normal position the valve through which
the steam enters and the exhaust valve are bothe closed, it being under-
stood that the steam is on the under side of the valve through which it
must afterwards enter.
A spring of suitable kind and construction is provided, the object of
which is to raise the one end of a horizontal lever, and to depress the
opposite end of the same, thereby keeping the valve through which the
steam enters closed. The tension thus exerted is so regulated as to be
just sufficient to counteract the tendency of the steam at its normal
pressure to open the entrance valve. The exhaust or relief valve is
simply closed but has no force applied to keep it closed. It will now
be understood that when the piston is at the top of the cylinder, the
break strap is just out of contact with the break wheel, and that when
the break is in operation and a certain amount of break power is
required to be exerted, this the breaksman supplies by depressing one
end of a horizontal lever, which is employed to give action to the
different parts, the opposite end of which said lever turns upon a fixed
stud or pivot, which force is through suitable links and levers made to
exert a certain force (increased by leverage) to open the steam admission
valve, and through a connecting rod and a second horizontal lever to
exert an equal force to close the exhaust valve; so that the steam will
continue to enter the cylinder until it attains a pressure sufficient to
balance the force exerted by the breaksman. The valves by sustaining
a pressure of steam on the piston proportionate to the force exerted by
the breaksman, cause a corresponding force to be exerted through the
break strap lever to tighten the break strap on the break wheel, and
thus the amount of break power exerted is caused to be exactly in
proportion to the smaller force exerted by the breaksman.
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