Improvements in Valve Gearing for Steam Engines.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Valve Gearing for Steam Engines.
We, LEONARD TURNER and HENRY VILLIERS PEGG, both of St. Peter's and Grey
Friars Works, Ipswich, in the County of Suffolk, do hereby declare the nature of
this invention to be as follows:-
To control cut off or expansion valves we employ a shaft governor having weights
which centrifugal force tends to move outwards or away from the shaft whilst
springs tend to draw the weights inwards or towards the shaft.
The weights are connected by links to a cam and in their movement to and from
the shaft when the speed of the engine varies, the weights partially rotate the cam
around the shaft or around the boss of the governor on which the cam is carried.
The cam is embraced by a cam fork and this is connected with the cut off valves.
The cam fork is caused by the cam to rock to and fro at each revolution and this
movement takes place sooner or later in the revolution according to the position of
the cam or in other words the speed at which the engine is running.
We prefer to employ Corliss or semi-rotary valves both as the main valves and
the cut off valves.
The main valves to control the admission of the exhaust may receive movement
from an eccentric. The cut off valves control the passage of the steam to the main
valves and by their earlier or later closing they determine the degree of expansion
of the steam in the cylinder.
The form of the cam is such as to cause the cut off valves to close suddenly.
In a modification of our invention we substitute an eccentric for the cam.
sometimes also use slide in place of semi-rotary valves.
We
LEONARD TURNER.
HENRY VILLIERS PEGG.
We, LEONARD TURNER and HENRY VILLIERS PEGG, both of St. Peter's and Grey
Friars Works, Ipswich, in the County of Suffolk, 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:-
To control cut off or expansion valves we employ a shaft governor having weights
which centrifugal force tends to move outwards or away from the shaft whilst
springs tend to draw the weights inwards or towards the shaft.

page_text: 1
The weights are connected by links to a cam and in their movement to and from
the shaft when the speed of the engine varies, the weights partially rotate the cam
around the shaft or around the boss of the governor on which the cam is carried.
The cam is embraced by a cam fork and this is connected with the cut off valves.
The cam fork is caused by the cam to rock to and fro at each revolution and this
movement takes place sooner or later in the revolution according to the position
of the cam or in other words the speed at which the engine is running.
We prefer to employ Corliss or semi-rotary valves both as the main valves and
the cut off valves.
The main valves to control the admission and the exhaust may receive move-
ment from an eccentric. The cut off valves control the passage of the steam to
the main valves and by their earlier or later closing they determine the degree of
expansion of the steam in the cylinder.
The form of the cam is such as to cause the cut off valves to close suddenly.
In a modification of our invention we substitute an eccentric for the cam... We
sometimes also use slide in place of semi-rotary valves.
The annexed drawings show the principal parts of a steam engine which is pro-
vided with a shaft governor, valves and valve gear in accordance with our inven
tion.
Figures 1 and 2 are both sectional elevations, Figure 2 illustrating a modifica-
tion of Figure 1.
a is the cylinder of the engine the lines b c and d represent respectively the
piston rod, the connecting rod, and the crank.
G indicates the shaft governor in its entirety. WW are the governor weights,
these are jointed at W W to the casing or frame plate of the governor which
is fast upon the crank shaft. SS are springs connected to the weights and to the
casing, they tend to draw the weights inwards towards the shaft. The drawing
indicates the position of these parts when the springs are extended by centrifugal
action.
C is the cam and L L are links connecting the cam with the weights so that
by the movement of the weights about the joints W₁ the cam is turned partly
around the axis or centre of the shaft.
F is the cam fork it is jointed to the pedestal at F1 and its arms are provided
with small rollers R which bear upon the cam. M M are the main valves and E E
are the expansion valves, they are both of the semi-rotary type; the valves are
seen in section in Figure 1. The main valves M are actuated by an eccentric the
central point of which is indicated in the drawing at e. At ff the rods and levers
which convey the motion of the eccentric to the main valves M are indicated.
The lines g g indicate rods and levers constituting the gear connecting the
expansion valves E with the cam fork F. Hence at certain points in the rotation
of the cam it moves the expansion valves E in such manner as to close them-
suddenly, preventing thereby steam from passing from the steam chest h to the
main valves M. The closing of the expansion valves will occur earlier or later in
the stroke according to the position in which the cam C is placed by the weights W.
and in turn the position of these weights is dependent upon the speed of rotation
of the shaft.
In Figure 2 G is the shaft governor as before but modified by the substitution
for the cam and cam fork of an eccentric X and eccentric strap X S.
The motion of the eccentric is conveyed to the expansion valves by gear rods
and levers 7 as shown in Figure 1.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
1. The combination in a steam engine of a shaft governor and a cam controlled
by the same, an expansion valve, and gear connecting the expansion valve with a
fork or lever operated by the cam and a main valve; the whole so arranged that

page_text: the cam causes the expansion valve to close suddenly and intercept the passage
of steam to the main valve and to the cylinder at a point in the stroke dependent
on the position in which the cam is placed by the shaft governor.
2. The modification illustrated by Figure 2 in which an eccentric is substituted
for the cam.
3. Apparatus substantially as described and illustrated by the annexed drawings
with semi-rotary valves to regulate the supply of steam to the cylinder of the
engine.
Dated this Oth dow of November 1907
LEONARD TURNER.
HENRY VILLIERS PEGG.