IMPROVED VALVE GEAR FOR STEAM ENGINES
Year: 1874

page_text: LETTERS PATENT to Robert McGlasson, the younger, of Brixton, in
.
the County of Surrey, for the Invention of "IMPROVED VALVE GEAR FOR
STEAM ENGINES."
Sealed the 16th October 1874, and dated the 18th August 1874.
PROVISIONAL SPECIFICATION left by the said Robert M'Glasson at
the Office of the Commissioners of Patents, with his Petition, on
the 18th August 1874.
I, ROBERT M'GLASSON, the younger, of Brixton, in the County of
Surrey, do hereby declare the nature of the said Invention for "IMPROVED
VALVE GEAR FOR STEAM ENGINES," to be as follows:-
This Invention relates to an improved arrangement of valve gear
for
steam engines which is specially designed for marine engines, although
it may be advantageously employed in connection with other engines.
I will describe one arrangement by way of example. I provide a
counter or valve shaft placed parallel to and above the main shaft. This
counter or valve shaft is driven by a spur wheel keyed on the main

page_text: shaft, working into another spur wheel of equal diameter loose on the
countershaft; this last spur wheel is provided with a stop which allows
it to revolve freely between the limits of two other stops fixed on the
countershaft. These stops are placed in such a position that when the
stop on the spur wheel abuts against the one or the other of the stops
on the countershaft it will cause the countershaft with its excentrics or
cranks for working the valves to revolve and operate those valves for
moving the engine ahead or astern, as the case may be, according to
whether the stop on the spur wheel abuts against the one or the other
stop on the countershaft. If the countershaft be turned round between
the limits of the stops upon it the valves will be moved, the steam
admitted the reverse way, and the motion be continued by the stop on
the spur wheel coming into contact with the other stop on the counter-
shaft.
:
For the purpose of turning the counter or valve shaft, as before
mentioned, a spur wheel of larger diameter than the motion wheels is
keyed on the main shaft, and in gear therewith a spur wheel of smaller
diameter than the motion wheels is permitted to run loose on the
countershaft. On either side of the latter wheel and fixed upon it are
half clutches, one right and one left handed, and in feather ways formed
in the countershaft slide the corresponding half clutches, one on cach
side of the spur wheel. These clutches are moved simultaneously to the
right or left to throw the one or other into gear, as may be required, by
an arrangement of levers terminating in a reversing handle, provided
with a catch spring and working on a quadrant face notched at the
centre to hold both clutches out of gear with those on the spur wheel
except when reversing.
When it is required to reverse the engines one of the clutches is
thrown into gear with its respective clutch on the smaller spur wheel,
thus temporarily connecting the latter to the counter or valve shaft.
This spur wheel in consequence of its quicker motion moves the counter-
shaft in advance of the main shaft of the engines, thus bringing the
stops above mentioned, and consequently the valves, into the reverse
position. From this it will be seen that the reversal of the engine is
effected by accelerating the motion of the valve shaft and valves. This
arrangement may be variously modified; for instance, I may fix the
clutches on the countershaft and make the spur wheel movable along
the said shaft, at the same time increasing the width of the spur wheel.

page_text: so that it may be thrown to the right or left of its centre position and
still gear with the larger spur wheel. The curved shape of the clutch
brings the lever back to the centre position, where it is held by the catch
spring before mentioned. Should the lever be thrown the wrong way
no damage will ensue as no action on the shaft can take place.
Auxiliary gear may be also provided to start the counter or valve shaft,
if necessary.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert M° Glasson in the Great Seal Patent Office
on the 15th February 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
M° GLASSON, the younger, of Brixton, in the County of Surrey, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of August, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Robert M° Glasson, Her special licenco
that I, the said Robert M Glasson, my executors, administrators, and
assigns, or such others as I, the said Robert M° Glasson, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVED
VALVE GEAR FOR STEAM ENGINES," upon the condition (amongst others)
that I, the said Robert M° Glasson, my executors or administrators, by
an instrument in writing under my, or their, or one of their hands
and seals, should particularly describo and ascertain the nature of the
said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Scal Patent Office within
six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Robert M° Glasson, do hereby
declare the nature of the said Invention, and in what manner the same

page_text: is to be performed, to be particularly described and ascertained in and
by the following statement, reference being had to the accompanying
Sheet of Drawings, and to the letters and figures marked thereon (that
is to say):-
. My Invention relates to valve gear specially designed for marine
steam engines, although it may be advantageously employed in con-
nection with other stationary engines, and it consists in an improved
arrangement whereby the engines are reversed by the momentum of the
moving parts communicated through the main shaft, the valves being
operated from a countershaft driven by the main shaft, and the reversal
being effected by accelerating the motion of the countershaft. For this
purpose the countershaft is so geared with the main shaft as to be driven
at an equal speed therewith. for working the valves, the said gearing
being however so applied as to allow of the temporary acceleration of
the speed of the countershaft by means of change gearing which is
thrown into action by means of a hand lever when it is required to
reverse the engine.
In order that my Invention may be more readily understood I have
illustrated one arrangement in the accompanying Drawings, in which
Figure 1 shows in plan a pair of marine engines with the improvement
of my Invention applied. Figure 2 is a cross section of the main and
countershafts on line 1-1, Figure 1, showing the gear for driving the
counter or valve shaft from the main shaft. Figure 3 is a similar
section on line 2-2, Figure 1, showing the gear for accelerating the
motion of the valve shaft in order to reverse the engines.
Figures 4 and 5 are transverse sections of the gear wheels shown in
Figures 2 and 3 respectively, but instead of spur gear as shown bevel
friction or chain gearing might be employed.
In Figure 1, A, A, are the cylinders; B, the crank shaft; D, D, the
valve rods operated from eccentrics E on a countershaft F. This counter
or valve shaft F is driven by a spur wheel G, Figure 2, keyed on the
main shaft B working into another spur wheel H of equal diameter
to G, loose on the countershaft F. This wheel H is provided with a
stop I, which allows it to revolve freely between the limits of two
abutments K, K³, on the countershaft F, and placed in such a position
that when the stop I abuts against K or K¹ it will cause the counter-
shaft F, with its eccentrics E or cranks for working the valves, to revolve
b

page_text: and operate those valves for moving the engine ahead or astern, as the
case may be, according to which of the two abutments K or K' the stop
I bears against. Now if the countershaft F be turned round in the
direction of the arrow, Figure 2, faster than the wheel H is moving; so
that the other abutment K¹ will come against stop I the valves will be
shifted and admit the steam the reverse way. In order to thus accelerate
the valve shaft F there is keyed on the main shaft B a spur wheel K* of
larger diameter than the wheel G, which spur wheel gears with another
spur wheel L of smaller diameter than wheel G, mounted loose on the
countershaft F. On either side of the wheel L, and fixed upon it, are
half clutches M, N, one right and one left handed, and in feather ways
O formed in the countershaft F slide the corresponding half clutches
M', N', one on either side of the spur wheel L. .
The half clutches M', N', are moved to the right or left to throw the
one or other into gear with its corresponding half clutch on the wheel L
by a forked lever P, each arm of which is also forked to embrace M², N'.
This lever is pivoted at P¹ and terminates in a handle provided with a
catch spring and working on a quadrant face R notched at the centre
to hold both clutches out of gear, as shown in Figure 1, except when
reversing.
i
When it is required to reverse the engines one of the clutches is
thrown into gear, thus temporarily connecting the wheel L to the valve
shaft F, whereby the latter, in consequence of the quicker motion of
wheel L is caused to run in advance of the main shaft B, thus bringing
the valves into the reverse position. This arrangement may be variously
modified, for instance, the half clutches M', N', may be fixed on the
countershaft, and the spur wheel L be movable along the said shaft, the
width of the spur wheel being increased so that it may be thrown to the
right or left of its centre position and still gear with the spur wheel K',
but I prefer the arrangement previously described. After reversal the
curved shape of the clutch teeth brings the lever back to the centre
position, when it is held by the catch spring before mentioned. Should
the lever be thrown the wrong way no damage will ensue, as no action
of the shaft can take place. Auxiliary gear S is also provided to start
the valve shaft when required.
Having described the nature of the Invention and the manner of
performing the same, I declare that what I claim as my Invention to be

page_text: protected by the herein-before in part recited Letters Patent is, effecting
the reversal of the engine by the momentum of the moving parts
communicated through the main shaft, substantially in the manner and
by means of an arrangement of gearing constructed and operated as
herein shown and described.
In witness whereof, I, the said Robert M. Glasson, the younger,
have hereunto set my hand and seal, this Thirteenth day of
February in the year of our Lord One thousand eight hundred
and seventy-five.