Automatic Expansion Gear for Motive Power Engines.
Year: 1892

page_text: Date of Application, 20th Dec., 1892
Complete Specification Left, 9th Jan., 1893-Accepted, 11th Feb., 1893
PROVISIONAL SPECIFICATION.
Automatic Expansion Gear for Motive Power Engines.
JOHN COCHRANE, Engineer, Barrhead near Glasgow, and WILLIAM WALKER,
Mechanical Engineer of Barrhead near Glasgow, do hereby declare the nature of
this invention to be as follows:-
Our invention consists in what is commonly known as trip gear, the period of
cut-off being automatically controlled by the governor.
In our arrangements of tripping gear, one of them is particularly applicable to
existing engines, and another arrangement can either be applied to engines having
drop or "Cornish " valves at each end of the cylinder, or cylinders provided with.
valves of the Corliss type.
The first part of our invention, namely that appertaining to the application of
the trip gear to existing engines, is in accordance with the following description.
We attach on the steam chest of the cylinder a box containing a valve, preferably
of "Cornish" construction, and the said valve is made to beat twice during every
revolution of the engine.
The cover of the valve box is formed of an upright frame, and designed to carry
the various parts of the tripping gear hereafter named, and the said frame also.
receives the governor with its driving gear, the apparatus in general being
altogether self contained. A lever receives an oscillating motion from an eccentric
on the main shaft, or other convenient part of the engine. This lever is keyed on
to a sleeve, the said sleeve having a suitable bearing or, journal formed on the side
of the upright frame. At one end of the sleeve, (and by preference cast with it):
is formed a vertical arm of circular section which also oscillates. The vertical
arm is bored out to receive a sliding circular trunk, the said sliding motion being
imparted to it in an upward or downward direction by the direct action of the
governor.
At the top of the sliding trunk, and on its two vibrating sides, are mounted two
steel driving pieces, and either one or the other of the driving pieces (as the case-
may be) is made to push horizontally a trip latch or detent piece in an outward
direction from the vertical centre line of the frame. Each trip latch or detent
piece is connected or pivotted to an L shaped lever, the lower limb of each lever,.
extending horizontally to the centre of the drop valve spindle, and engaging
thereto by having toggles formed on the end of each limb, and' embraced by a
square eye formed on the said drop valve spindle, whereby a lifting motion is given
to the drop valve spindle by each toggle alternately.
The action of the governor for the purpose of determining the period of tripping.
is as follows:-The top of the sliding trunk with its driving faces describe an arc
of a circle in their oscillating movement, and the detent latches are alternately
pushed outwards on a horizontal plane or nearly so.
The consequence of this is that the steel faces, namely the driver and the driven,
leave each other sooner or later, upon which the drop valve is released, thereby.
returning rapidly and quietly to its seat, through the intervention of the ordinary
air "dash-put."
The duration of time in the contact of the respective driving
faces, absolutely depends upon the height to which the sliding trunk, with its
driving faces are raised or lowered by the governor, as for instance, when the said
governor shall be in lowest position, the initial engaging faces may be ths to **
giving a long range cut-off, or on the other hand, when the governor shall be at its
maximum velocity or highest point, the initial engaging faces may only be th
or nd, or even nil, thus controlling automatically the speed of the engine, in
accordance with the load or fluctuations of boiler pressure.

page_text: The point at which either of the driving faces initially engage with either detent
latch always occurs at a time when the vertical oscillating lever is in its normal
position or slowest travel, and consequently a minimum concussion and almost
noiseless action is maintained. When either of the driving pieces are making
their inward or return stroke, the detent latches are tilted up from their fulcrums
by either of the said driving faces on, their top side the ends of the said detent
latches being inclined or bevilled on their bottom sides nearest to the engaging
faces, and fall back into place by their own gravitation for another outward
push to enable the drop valve to be again lifted. The said detent latches are
prevented from falling too deep into gear by pads or supports cast on the
vertical frame, these pads supporting their respective detent latches in their
outward and inward movement, except when tilted up by the tops of the driving
faces already named.
In the application of this mechanism to engines having a Cornish or drop valve
located at each end of the cylinder, the following description will be sufficient.
A bell crank or L shaped lever is attached to each vertical valve spindle, the
horizontal portion being connected at its end to the said valve spindle, and the
fulcrum is formed on a fixing placed on the top of each valve box, the said
fixing being arranged to contain an air "dash-pot" with the usual springs for
accelerating the closing of the valves in their descent. The other part of the
bell crank or shaped lever is arranged to hang down vertical or thereabouts,
and a connecting rod is attached to each end of the bell crank levers. Each
connecting rod leads away towards the centre of the engine cylinder, the ends
of the said connecting rods in their sliding motion longitudinally, resting on
supporting pads. The inner ends of each connecting rod are provided with steel.
faced tripping ends. The vertical oscillating lever derives its to and fro motion
from an eccentric on the crank shaft, or may be actuated from any other convenient
source.
The vertical oscillating lever is bored out to receive a sliding trunk, on the top
of which is mounted the steel driving pieces, and the method of pushing outwards
either of the connecting rods, and so lifting one or other of the drop valves is
carried out in precisely the same manner to what has already been described in
reference to the application of the apparatus to existing engines, the governor
performing similar duties under similar conditions already specified. The same
mechanical action and principles are involved when operating Corliss valves, the
outer ends of the connecting rods being attached direct to the levers keyed to each
Corliss valve spindle, the said levers hanging downwards and nearly vertical.
The following modification of our mechanism may be described as follows,-
viz. Instead of the vertical oscillating lever being bored out to receive a sliding
trunk, it is made solid, and the method of increasing or decreasing the depth of the
engaging and driving faces, (and consequent variable period of tripping) is brought
about by applying a cam underneath the end of each connecting rod. The
governor is arranged to partially rotate each cam on its axis, and therefore raises
or lowers the connecting rods deeper or shallower into gear. Each cam fulfils the
duty of a resting pad for the inner ends of each connecting rod, after such con-
necting rod ends are tilted up, by the passing underneath of the driving faces on
top side of the oscillating lever.
Dated this 10th 1
1.
1000
JOHN COCHRANE.
WILLIAM WALKER.

page_text: COMPLETE SPECIFICATION.
Automatic Expansion Gear for Motive Power Engines.
JOHN COCHRANE, Engineer, Barrhead near Glasgow and WILLIAM WALKER
Mechanical Engineer of Barrhead near Glasgow, 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 consists in what is commonly known as trip gear, the period of
cut-off being automatically controlled by the governor.
">
In our arrangements of tripping gear, one of them is particularly applicable to
existing engines, and another arrangement can either be applied to engines having
drop or "Cornish valves at each end of the cylinder, or cylinders provided with
valves of the "Corliss" type. The first part of our invention, namely that per-
taining to the application of the trip gear to existing engines, is in accordance with
the following description.
::
We attach on the steam chest of the cylinder a box containing a valve, pre-
ferably of Cornish construction, and the said valve is made to beat twice during
every revolution of the engine. The cover of the valve box is formed of an
upright frame, and designed to carry the various parts of the tripping gear here-
after named, and the said frame also receives the governor with its driving gear,
A lever receives an
the apparatus in general being altogether self contained.
oscillating motion from an eccentric on the main shaft or other convenient part of
the engine. This lever is keyed on to a sleeve, the said sleeve having a suitable
bearing or journal formed on the side of the upright frame. At one end of the
sleeve, (and by preference cast with it) is formed a vertical arm of circular section
which also oscillates. The vertical arm is bored out to receive a sliding circular
trunk, the said sliding motion being imparted to it in an upward or downward
direction by the direct action of the governor.
At the top of the sliding trunk, and on its two vibrating sides, are mounted two
steel driving pieces, and either one or the other of the driving pieces, (as the case
may be) is made to push tangentally a trip latch or detent piece in an outward
direction from the vertical centre line of the frame. Each trip latch or detent
piece is connected or pivotted to a shaped lever, the lower limb of each lever,
extending horizontally to the centre of the drop valve spindle, and engaging
thereto by having toggles formed on the end of each limb, and embraced by a
square eye formed on the said drop valve spindle, whereby a lifting motion is given
to the drop valve spindle by each toggle alternately.
The action of the governor for the purpose of determining the period of tripping
is as follows:-The top of the sliding trunk, with its driving faces, describe an arc
of a circle in their oscillating moveinent, and the detent latches are alternately
pushed outwards in a horizontal plane or nearly so.
The consequence of this is that the steel faces, namely the driver and the driven,
leave each other sooner or later, upon which the drop valve is released, thereby
returning rapidly and quietly to its seat, through the intervention of the ordinary
air "dashpot."
The duration of time in the contact of the respective driving faces, absolutely
depends upon the height to which the sliding trunk, with its driving faces are
raised or lowered by the governor, as for instance when the said governor shall be
in its lowest position, the initial engaging faces may be ths to inch giving a long
range cut-off, or on the other hand, when the governor shall be at its maximum
velocity or highest point, the initial engaging faces may only be 16th or 3" or
even nil, thus controlling automatically the speed of the engine, in accordance with
the load of fluctuations of boiler pressure.
32
The point at which either of the driving faces initially engage with either detent
latch always occurs at a time when the vertical oscillating lever is in its normal
position or slowest travel, and consequently a minimum concussion, and almost

page_text: noiseless action is maintained. When either of the driving pieces are making
their inward or return stroke, the detent latches are tilted up from their fulcrums
by either of the said driving faces on their top side, the ends of the said detent
latches being inclined or bevilled on their bottom sides, nearest to the engaging
faces, and fall back into place by their own gravitation for another outward push,
to enable the drop valve to be again lifted.
The said detent latches are prevented from falling too deep into gear by pads or
supports cast on the vertical frame, these pads supporting their respective detent
latches in their outward and inward movement, except when tilted up by the top of
the driving faces already named.
In the application of this mechanism to engines having a "Cornish" or drop
valve located at each end of the cylinder, the following description will be suffi-
cient. A bell crank or shaped lever is attached to each vertical valve spindle,
the horizontal portion being connected at its end to the said valve spindle, and the
fulcrum is formed on a fixing, placed on the top of each valve box, the said fixing
being arranged to contain an air "dashpot" with the usual springs for accelerating
the closing of the valves in their descent. The other part of the bell crank or
L shaped lever is arranged to hang down vertical or thereabouts, and a connecting
rod or detent latch is attached to each end of the bell crank levers.
Each connecting rod or detent latch leads away towards the centre of the engine
cylinder, the ends of the said connecting rods or detent latches in their sliding
motion longitudinally, resting on supporting pads. The inner ends of each con-
necting rod or detent latch are provided with steel faced tripping ends. The
vertical oscillating lever derives its to and fro motion from an eccentric on the
crank shaft, or may be actuated from any other convenient source.
The vertical oscillating lever is bored out to receive a sliding trunk on the end
of which is mounted the steel driving pieces, and the method of pushing outwards
either of the connecting rods or detent latches, and so lifting one or other of the
drop valves, is carried out in precisely the same manner, to what has been already
described in reference to the application of the apparatus to existing engines, the
governor performing similar duties under similar conditions already specified. The
same mechanical action and principles are involved when operating
"Corliss
valves, the outer ends of the connecting rods or detent latches, being attached
direct to the levers, keyed to each "Corliss" valve spindle.
"
The following modification of our mechanism may be described as follows:-
Instead of the oscillating lever being bored out to receive a sliding trunk, it is
made solid, and the method of increasing or decreasing the depth of the engaging
and driving faces (and consequent variable period of tripping) is brought about
by applying a cam underneath the end of each connecting rod or detent latch.
The governor is arranged to partially rotate each cam on its axis, and therefore
raises or lowers the connecting rods or detent latches deeper or shallower into gear.
Each cam fulfils the duty of a resting pad for the inner end of each detent latch,
after such detent latches have been tilted up, by the passing underneath of either
of the driving faces (as the case may be) located at the end of the said oscillating
lever.
In order that our invention may be clearly understood, drawing No. ! illustrates
the mechanism as applied to existing engines. Fig. 1 and 2, shews upright views
of the gear, and Figs. 3, 4 and 5, sectional plans of the same. The governor
raises and lowers the sliding trunk (T), by means of the sliding central spindle (C),
a light connecting rod (D) being coupled to the pin (J) and leading down to the
lower pin (K). The pin (K) passes through the trunk (T) and also the vertical
oscillating lever (L), a slot (S) being formed on each side of the said oscillating
lever, to receive the pin (K), so as to prevent the trunk (T) from rotating, when
being raised or lowered by the action of the governor. The drawing at Fig. 1 and
Fig. 2 shews the governor at its lowest point or slowest velocity, and the sliding
trunk (T) is therefore shewn with its driving faces (F and F¹) in their highest
position, and giving off the longest duration of time for pushing outwards tangentally

page_text: either of the detent latches (P and P¹). This consequently permits either of the
bell cranks or L shaped levers (Q and Q¹) to keep up the Cornish valve (X)
from its seat during the longest period of time, prior to its being released, by the
driving faces (F and F¹) leaving the driven face, of either of the detent latches (P
and P) at (G and G¹), in consequence of the detent latches moving outwards in a
straight line or nearly so, while the driving faces (F and F¹) describe an arc of a.
circle in either one direction or the other as the case may be.
The highest position of the governor will depress the sliding trunk (T) and its
driving faces (F and F') to a position clear of the driven faces (G and G¹), and
under these conditions, no lift of the Cornish valve (X) could occur, so that the
range of cut-off' would be brought to zero. The eccentric on the crank shaft,.
(which imparts a vibrating motion to the main lever (M) Fig. 2) may have such a
relation of angularity with that of the engine crank, that ranges of expansion may
be derived from ths of the stroke of the engine, down to zero. Fig. 1, Sheet No. 1,.
shews each detent latch (P and P¹) resting on their respective pads (O and O¹),.
the oscillating lever (L) being just upon the point of returning from right to left
In this return,
in the direction of the arrow as shewn at Fig. 1, Sheet No. 1.
motion from right to left, the top edge of the driving face is bevilled as shewn and.
marked (16) and tilts up the end of the detent latch, which is also bevilled as
marked at (18) and each detent latch (as the case may be) fall into gear again,
from their fulcrums (29) and (22) by their own gravitation after the passing under-.
Sheet
neath of either of the driving faces (F and F') in either inward direction.
No. 2 shews our invention when applied to engines having drop or Cornish valves.
at each end of the cylinder. The detent latches are again shewn at (3 and 4), and
the pads upon which the said latches fall into gear at (5 and 6). The sliding.
trunk (T) with its driving faces (8 and 10) is shewn at Fig. 1, and the governor
rods, for raising or lowering the trunk (T) are marked (12 and 14) at Fig. 2. The
fulcrums from which the detent latches (3 and 4) fall into gear by gravitation are
indexed (G and G³) respectively. The method and principles for varying the.
period of release of the Cornish valve, and consequent time of cut-off are carried
out in the same manner as previously described, with regard to the application of
our mechanism to existing engines and shewn on Sheet No. 1. Sheet No. 3 Fig. 1
shews the application of our gear to Corliss engines, the arrangement being carried.
out on the same lines for varying the points of cut-off as already described, the
only difference being the attachment of the detent latches (3 and 4) to a fulcrum.
at the end of each Corliss valve spindle lever (G and G¹) respectively. Sheet
No. 3 Fig. 2, shews a modification of our valve gear, and in this instance is
applied to a cylinder also having Corliss valves. The oscillating lever (L) is
not made hollow, to receive a sliding trunk or its equivalent, and its end driving
faces (F and F¹) are not varied by the governor. The changing depths to.
which the driving faces (F and F¹) engage with the ends of the detent latches.
at (0 and O¹) and the consequent variation of cut-off is brought about by the
governor through the levers (P and P¹) varying the position of the tail ends of
the cams (C and C¹) thereby producing equivalent results, to what has been.
previously referred to.
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 :-
1st. The use of an oscillating lever, fitted with fixed or variable steel driving
faces, which when oscillating describe the arc of a circle, and force or draw detent
latches, in a tangental line, until a point of release is reached, substantially as and
for the purpose herein before described.
2nd. The use of detent latches, pivotted on fulcrums, wherefrom they are arranged
to fall on pads made to receive them, substantially as and for the purpose herein-.
before described.
3rd. An oscillating lever actuated from an eccentric, or other suitable means,.

page_text: made hollow and circular to receive a sliding trunk fitted with steel driving
faces or its equivalent, such trunk being drawn inwardly or outwardly by the
governor, substantially as and for the purpose herein before described.
4th. The application of cams or their equivalents for varying the depth of gear,
to which the ends of the detent levers or catches shall engage, such cams or their 5
equivalents acting as pads for receiving such detent latches when falling from their
respective fulcrums, substantially as and for the purpose hereinbefore described.
Dated this 7th day of January 1893.
JOHN COCHRANE.
WILLIAM WALKER.