Improvements in Steam Engine Valves and Gear for Working them.
Year: 1894

page_text: Date of Application, 24th July, 1894-Accepted. 25th Aug., 1894
COMPLETE SPECIFICATION.
Improvements in Steam Engine Valves and Gear for Working them.
We, JAMES THOMPSON MARSHALL, and REGINALD WIGRAM, both of The
Steam Plough Works, Leeds, in the County of York, Engineers, 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:-
Our invention relates to the construction and arrangement of the cylinder and
valves of a steam engine and the gear for working the valves, as we shall describe
with reference to the accompanying drawings.
Fig. 1 is a longitudinal section of a horizontal steam cylinder fitted with valves
according to our invention.
Fig. 2 is a longitudinal section of one of the valves shewn in two parts, the one
being a continuation of the other at the line Z.
Fig. 3 is a side view of the connections for working the cut off valves.
Fig. 4 is a back view of one of the cut off valves.
The cylinder A has at each end a cover a in which is a partially rotating main
valve B and within it a partially rotating cut off or expansion valve C. The main
valve B is free to move towards the facing so as to allow for wear, its ends being
fitted to slide in discs one of which 6' is fixed on a tubular spindle 6 and the
other 68 is connected to b¹ by a bar 6. Through the tubular spindle 6³ passes the
spindle c of the expansion valve which is also free to move and pressed by springs
so as to make up for wear, flanges c² on its back at each end and in the middle
fitting on parts of the spindle c which are of rectangular section.
The main valve spindles 62 have on them arms jointed to the rod of the main
eccentric on the crank shaft; but these connections are not shewn, being of
usual kind.
The cut off valve spindles c have on them arms which are linked by a
connecting rod e¹ to a block e fitted to slide in a slotted link E. On K the same
pivot with E and fixed to E is another slotted link F in which is fitted to slide a
block jointed to the rod g of a second or expansion eccentric on the crank shaft.
The rods e and g are connected by links and g¹ to the opposite arms of a
lever H, the one arm of which is engaged with the sliding boss of a centrifugal
governor J.
The two arms of the main valves at the opposite ends of the cylinder, and also
the two arms of the expansion valves are linked together.
When, owing to excess of speed, the boss of the governor J rises, it raises the
block e towards the pivot K of the slotted link E, and it lowers the block f away
from the pivot in the slotted link F. The stroke of the link F and at the same
time the stroke of the block e are thus very swiftly reduced, and consequently the
stroke of the cut off valves C is lessened, causing cut off at an earlier part of the
stroke until, when the speed becomes normal, the sliding boss of the governor J
descends lowering the block e and raising f, thus increasing the stroke of the
expansion valves C so that they cut off at a later period of the stroke.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. A steam engine cylinder having in its end covers partially rotating main
valves and within them partially rotating cut off valves, substantially as
described.

page_text: 2. In combination with the cut off valves above referred to, the arms and links
and the eccentric for working them, a pair of slotted links oscillating together and
having sliding blocks connected to a lever moved by the governor, substantially as
and for the purposes set forth.
Dated this 24th day of Inl, 1901
ABEL & IMRAY,
Agents for the Applicants.