Improvements in Trip Expansion Gear of Steam Engines.
Year: 1886

page_text: Date of Application, 11th Sept., 1886.
Complete Left, 9th May, 1887.
Complete Accepted, 10th June, 1887.
PROVISIONAL SPECIFICATION.
Improvements in Trip Expansion Gear of Steam Engines.
I WILLIAM CAMERON of Lincoln in the County of Lincolshire, Mechanical Engineer
do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in trip expansion Gear which is controlled by
a Governor and is suitable for Corliss drop and slide valves.
The ends of a horizontal rocking lever which receives a rocking motion from an
eccentric form faces which at certain periods of an oscillation bear upon fingers
pivoted on levers, these levers being connected to the valve or valves.
Suitable springs bear on the fingers to keep them up to their stop levers.
These stop levers are pivoted one at each end equidistance from and on the same
horizontal line as the centre of oscillation of the rocking lever.
They control the under or overlap (as the case may be) of the fingers in relation to
the ends of the rocking lever.
The stop levers are connected to the Governor by suitable mechanism and they are
compelled to move in such a manner that those part of these levers which form the
stops move in an approximate straight line during an oscillation.
When there are two valves each valve is opened once in an oscillation.
If one valve be employed as may be the case when drop valves are used it requires
to be twice opened during an oscillation.
The release or triping of the valve is caused by that end of the rocking lever which
is bearing on its finger and moving it so as to open the valve sliping from off that
finger owing to the angular motion of the rocking lever end forming the face.
This will occur at an earlier or later period of the stroke according as the Governor
allows the fingers to come more or less under or over the ends of the rocking lever.
A spring or other suitable means may be employed to close the valves.
The position of the stop levers may be controlled by hand instead of being under
the control of a Governor.

page_text: In some cases it is preferable to have two rocking levers which may be actuated by
the same or seperate eccentrics each lever having one stop lever. Where Corliss valves
are used the oscillations given to the exhaust valves may be in some cases employed
to operate the induction valves, each rocking lever being secured to the valve
spindles or trunions of the exhaust valves.
The stop levers may also be so arranged that during an oscillation of the rocking
lever they act in conjunction with the angular movement of the rocking lever to cause
the fingers to be released.
The centrifugal Governor may so act on the stop levers that only the movement of
the Governor balls from their mean position produces a movement. The Governor
balls being enabled to return to the mean position without producing any effect on the
stop levers.
COMPLETE SPECIFICATION.
Improvements in Trip Expansion Gear of Steam Engines.
I WILLIAM CAMERON of Maryport in the County of Cumberland Mechanical
Engineer 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:—
This invention relates to improvements in the means of triping or disengaging
the parts which transmit the motion of the eccentric to the valve or valves.
This end is attained by forming the ends of a horizontal rocking lever receiving
motion from an eccentric into faces which at certain periods during an oscillation bear
upon fingers pivoted on levers connected to a valve or valves.
Suitable springs bear on the fingers or they may be so designed that the actions of
their own weight is sufficient to keep and bring them up to their stop levers.
These stop levers are pivoted one at each end equidistant from and on the same
horizontal line as the centre of oscillation of the rocking lever when the stop levers
are arranged to act in conjunction with the angular movement of the rocking lever
the centres on which the stop levers are pivoted are not compelled to fall on the
before mentioned horizontal line. The stop levers are controlled by the governor in
such a manner that they control the amount of contact between the rocking lever or
levers and their fingers so that the action of the governor caused by an increase of
the speed of the engine decreases the amount of contact and a decrease of the speed
causes increase of the contact or a decrease or increase in the length of time they are

page_text: in contact. Therefore the fingers will slip from off or from under the ends of the
rocking lever in a lesser or greater period of the stroke according to the position
taken up by the Governor.
The range available by this means is from Zero to g of the stroke.
When one valve is employed it must be lifted twice during an oscillation that is
twice in one revolution of the engine.
The range obtainable with the single valve is from Zero to
stroke.
In some cases it is preferable to have separate rocking levers each operated by the
same or seperated eccentrics each lever having one stop lever.
The position of the stop levers may be controlled by hand instead of being under
the control of a governor.
In order that this invention may be fully understood I will now proceed to explain
the annexed drawings.
Fig. 1 shews a side elevation partly in section of an arrangement of this gear. It
being arranged to operate two independent valves.
The rocking lever A which is oscillated by an eccentric has steel faces at the
ends B, B one of which is shewn is contact with the finger C, connected to the valve D,
by the lever E. The stop levers F F one of which is acting on the finger C, are
connected to the governor spindle by the swinging rod G, G and the bell cranks H, H.
The ends of the faces B, B of the rocking lever A travel in an are so that during the
upward movement of B, the finger C, will be released the extent of the upward travel
before release depending upon the amount with which the finger C, overlaped the
face B, this again depending upon the stop lever F which is controlled by the
governor.
The ends of the stop levers F, F, being connected to the bell cranks H, H while
their lower ends are pivoted on the rocking lever A at J J, those parts of the
levers F, F which form the stops move in an approximate straight line during an
oscillation of the rocking lever A.
The valve D is brought quickly to its seat by the spring K but without shock or
noise being effectively cushioned by the air cushion L. A regulator M being used to
increase or diminish the resistance of the air.
The end B, of the rocking lever A which is moving downwards pushes the finger C,
aside until its downward travel is completed.
The finger will then be clear and will immediately swing over face B ready to be
operated on during the upward movement. The finger may be caused to swing over
by a suitable spring or by its own weight.
Fig. 2 shews an arrangement applicable to slide valves the action and essential parts
are similar to those already described in connection with Fig. 1.
They are distinguished by the same letters as similar parts of Fig. 1.
Fig. 3 shews a modification of the gear which consists of a rocking lever A having
steel faces B, B which act on fingers C, C which are hung on levers E, E connected
to the valves (not shown).
The stop levers B, B (which controls the amount of overlap or underlap the
fingers C, C have on the faces B, B) are hung on links N, N which are pivoted on
the rocking lever A. The vertical ends of the stop levers B₂ B, form stop for
the fingers C, C while the horizontal ends are secured to the Governor spindle fork O
by a pin on which they are free to move."
The fork O is guided by a friction roller P so as to take any side thrust.
As the rocking lever A oscillates the vertical ends of the stop levers B, B act in
conjunction with the angular movement of the rocking lever A to release the
fingers C, C during the upward or downward movement (as the case may be) of the
rocking lever A.
The valves are closed in the same manner as that described in connection with
Fig. 1.
Fig. 4 shews an arrangement of the modification operating one valve which requires
to be moved twice during one complete oscillation of the rocking lever. What is

page_text: meant by a complete oscillation is the movement of any one point in the lever for
instance the end from a point in its travel until it again arrives at that same point.
The trip gear is the same as in Fig. 3 but arranged to operate one valve.
The rocking lever A which is rocked by an eccentric has steel faces at the ends B, B
which engage with fingers C, C pivoted on levers E, E which are connected to the
valve D.
In this case when the rocking lever A is lying horizontal the valve will be closed.
On the rocking lever A receiving an oscillation one end will be depressed forcing
down the finger C, and opening the valve D until by the angular movement of the
rocking lever A. or by the conjoined action of the stop lever F and the angular move-
ment finger C, is released from face B, and the valve D closed by means of a suitable
spring and is cushioned in the usual way by the dash pot K. During the upward
movement of that end, finger. C, is pushed aside until the end of the rocking lever A
rises into its horizontal position, when finger C, is allowed to come under the face.
A spring may be employed for that purpose or the finger C, may be so designed that
its centre of gravity lies in such a position as will bring it into the required position.
The above operations are now gone through by the end B causing it to open the
valve D through finger C.
The stop levers are hung on links or on a link which is pivoted on the lever A in
the same manner as already described in connection with Fig. 3.
Although the gear is here shewn as being controlled by a governor it will readily
be understood that the points of release can be fixed by hand.
Having now particularly described and ascertained the nature of my invention and
in what manner the same is to be performed I declare that what I claim is
1. An expansion or trip gear consisting of a rocking lever whose ends from faces
which act on fingers pivoted on a lever connected to a valve or valves and two stop
levers pivoted at the ends of the before mentioned rocking lever and connected by a
swinging rod to two bell cranks or their equivalents so that during an oscillation of
the rocking lever parts of the stop lever which form stop for the fingers move in
an approximate straight line and at the same time are capable of being advanced or
withdrawn by the action of a governor or by hand substantially as shewn and
described.
2. An expansion or trip gear consisting of a rocking lever whose ends form faces
which act on fingers pivoted on levers connected to a valve or valves and two stop
levers hung on a link or links the link or links being pivoted on the rocking lever.
The vertical ends of the stop levers forming stops for the beforementioned fingers, the
horizonal ends being jointed to a fork which is guided by a friction roller and con-
nected to the governor rod or its equivalent so that a vertical movement of the
governor rod or its equivalent causes the vertical end of the stop lever to increase or
decrease the amount of contact between the fingers and the faces of the rocking lever
substantially as shewn and described.
Dated this 5th day of May 1887.