IN ROTARY MOTIVE POWER ENGINES
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by John Walker at the Office of the
Commissioners of Patents on the 19th March 1880.
JOHN WALKER, of Glasgow, in the County of Lanark, North Britain.
MENTS IN ROTARY MOTIVE POWER ENGINES."
" IMPROVE-
This Invention relates to a new or improved construction of rotary engine to be
actuated by steam or other fluid under pressure, and which is specially designed so
as to be capable of being easily reversed or driven in either direction, and in the
case of a steam engine also fitted with a new adjustable eccentric and duplex valve
arrangement, by means of which the admission of steam to the cylinder can be
controlled to cut off at any part of the revolution or stroke, and so obtain any
desired degree of expansion.
The improved engine comprises a large cylinder or cylindrical casing truly turned
or bored inside, which may be cast in one piece, but which in the case of large
engines may be made in segments, fitted with flanged end covers, in which are
formed or fitted the bearings of a central revolving shaft or spindle.
On this spindle there is keyed a revolving piston, which is preferable made for
lightness in the form of a hollow drum, the full breadth of the cylinder between
the end covers, and of somewhat less diameter than the inside of the cylinder
chamber, and which is fitted with annular ring packing at one or both ends. The
revolving drum has a broad deep recess or groove cut transversely in its periphery,
into which is fitted a transverse bar, or rebate, or piston proper, reaching out to
and bearing on the inner surface of the cylinder its full breadth, against which it
is pressed by a spring, or fitted with packing, so as to be steam tight; and the
piston drum is driven round by the pressure of the steam on the surface of this
transverse piston, the area of-which-is equal to the product of the breadth of
the piston into the space between the drum and the inner surface of the --
cylinder forming the fluid pressure cylinder proper. Steam is admitted to the
cylinder at the back of this rebate by an annular oscillating or reciprocating valve,
fitted in a box outside the cylinder, through a port from this valve cut through a
segmental buttress or re-acting abutment entering at both ends through the cylinder
casing, also having an oscillating or reciprocating motion; and one end of this
segmental buttress is arranged, as will hereinafter be described, always to bear
pressure tight against the periphery of the revolving drum, and only be lifted once
in every revolution by the rebate, piston, or bar which is suitably angled to raise it

page_text: as a cam, or it might be raised by a separate cam or cams while the rebate is
passing.
The steam is thus prevented passing back and round the cylinder, excepting in
the direction to propel the piston and rebate forward, but when the rebate travels
round to and past the second end or edge of the oscillating re-acting segment, the
steam, which has meanwhile been cut off by the central oscillating admission valve,
and is now fully expanded, escapes through an exhaust port in this buttress, or its
bearing seat past the sides of the inlet port to the atmosphere or to a condenser.
The rebate continues its travel with the drum piston, and comes in contact with
the first edge of the segment to raise and pass it and receive a further supply of
pressure steam for the next revolution, and a further exhaust now takes place
through the port or recess in the inner face of the buttress, the exhaust passing
preferably through a channel between the segmental buttress and the central valve
casing, and is thence led away by a pipe entered at one end. The admission valve
for the steam is preferably made duplex with an outer tubular or cylindrical liner
for reversing with turned bearing surfaces opposite the steam admission ports, and
where the openings are formed in it opposite each other for the passage of the steami
to the ports, and also formed. with a central segmental valve for regulating the
admission of the steam and the cut-off or expansion. The central reciprocating or
oscillating steam valve is fitted inside this liner or reversing valve on a spindle
actuated by means of a lever fitted at one end, which is connected to the rod of
an eccentric on the main revolving shaft of the piston or drum so as to be
reciprocated with the valve as a rocking centre by the action of the eccentric, and
the reciprocation or circular travel of the valve may be controlled or regulated to
vary the cut-off and amount of expansion of the steam by varying or changing
the position of the pin in the valve lever at which the eccentric rod is connected,
which variation of the acting length of the valve lever may be effected by
forming a slot in it in which the eccentric rod end may be adjusted or by a
screw on the lever, and nut on the eccentric rod or other equivalent means
operated when desired by a hand wheel. The liner in the valve casing is formed
with duplex inlet ports in it opposite each other, and it may be turned round or
partially rotated by means of a hand lever outside when desired to bring either of
these openings opposite the steam admission ports through the casing and
segmental buttress leading to the cylinder for the purpose of actuating the engine
in either direction. And when the engine is thus made capable of reversing the
segmental buttress enclosing the valve is fitted in an outer steam casing, and a
projecting snug or snugs are formed on its upper outer edge free to reciprocate
with the buttress between stops on its containing case.
A screw nut is fitted between these snugs, through which a screw passes,
actuated by a hand wheel, and when it is desired to reverse the rotation of the
engine the segmental buttress is drawn partially round by means of the screw and nut
until a sliding plate valve fitted in the steam casing, immediately above the buttress,
and which is moved by the same means with the screw nut, opens and admits
steam through ports in the casing to act on a shoulder formed on the buttress and
force it completely round till its opposite edge is kept down to divide the pressure
eteam and exhaust sides of the cylinder, or the buttress might be formed in two
parts with the steam acting on the back ends, the one part being taken out of
gear by the screw and hand wheel or other equivalent whilst the other is brought
into action. The second edge of the buttress is now the one which is kept always
pressed down on the revolving drum to be lifted only by the rebate or piston
proper in passing; and the annular oscillating valve liner being then also turned by
its hand lever till the position of its duplex ports is reversed steam is now admitted
through the port in the edge or side of the buttress which presses on the revolving
drum, and the rebate and drum are consequently driven in the opposite direction
from what they were before.
The details of the engine may obviously be modified to obtain still the action
described, but in every case the essential features of the present improvements will

page_text: he retained, that is, the arrangement of the oscillating duplex valve for admitting
the steam to and for reversing the engine actuated by an eccentric rod and lever,
the acting length or arm of which can be adjusted to cut-off the steam at any
desired part of the stroke or revolution, and the arrangement of segmental buttress
or buttresses, through the ports of which the steam is admitted and exhausted
oscillated by the action of the piston or engine itself or by a special cam or cams,
and also capable of being moved by hand for the purpose of reversing the direction
of the engine's rotation.