AN IMPROVEMENT IN TRIGGER GEAR FOR ENGINE VALVES
Year: 1884

page_text: We, CHARLES JOHN GALLOWAY and JOHN HENRY BECKWITH both of Manchester
in the County of Lancaster, Engineers, do hereby declare the nature of our
Invention for AN IMPROVEMENT IN TRIGGER GEAR FOR ENGINE VALVES" to
be as follows:-
In the Specification to a Patent granted to us on the 13th June 1876, No. 2439,
we described trigger gear applied to the admission slides of an engine cylinder, the
trigger in each case being released either at a definite part of the stroke, or at a part
determined by the governor, so as to allow the slide to be pressed back and to
close the admission port. The trigger gear described in the said Specification
consisted of a plate fixed on the slide rod and presenting its edge to another plate
fixed on a bent lever pivotted on the eccentric rod. When the eccentric rod began
its stroke, the lever on it was in such a position that its plate engaged with that
of the slide rod, and consequently as the eccentric rod moved, the slide rod was
pushed along with it opening the cylinder port, until the lever became so far
cauted by the drag of a rod controlled by the governor that the plate on the lever
was raised out of engagement with the plate on the slide rod, and consequently the
latter was left free to be pushed back, closing the cylinder port. Our present
Invention relates to a construction and arrangement of trigger gear of this kind,
whereby its action is rendered more certain, and its application to various forms
of engines is facilitated. For this purpose, we pivot on the end of the trigger
lever or lever that carries the trigger plate, one arm of a three armed lever, the
opposite arm of which carries a roller. An upright arm between these is jointed
to a horizontal arm which has at its end, in an inclined attitude, a curved slot like
that in the ordinary link motion of a steam engine. This arm, with its curved
slot, is connected to the governor lever, so as to be raised or lowered according as
the speed of the governor varies. In the curved slot is engaged a pin carried at
the top of an upright post fixed on the eccentric rod. As the eccentric travels
round in its circular path, the pin at the top of this post besides having this to and
fro movement due to the stroke of the eccentric, and consequently accompanying
the eccentric rod and slide rod while they are engaged together, has an additional
movement due to the angular attitude which the eccentric rod has to take during
its stroke, and by this movement communicated through the slotted link to the
upright arm of the three armed lever above mentioned, the lever is canted. As

page_text: the roller carried by one arm of this lever moves along a fixed guide its centre
becomes the fulcrum on which the lever is canted, and the arm jointed to the
trigger lever is consequently raised, lifting the trigger plate out of engagement with
the plate on the slide rod and so releasing the latter. The arm having the curved
slot as stated above, is raised and lowered by its connection to the governor lever
and the slot is placed at such inclination that according as the speed of the governor
exceeds or falls short of its normal speed the release of the slide rod and the
consequent cut off is effected at an earlier or later part of the stroke.
The guide on which the roller of the three armed lever runs is made with its end
nearest the eccentric at a lower level than the other end, so as to insure that when
the three armed lever is at the back, end or commencement of its stroke the guide
on which it rests will allow it to assume such a position as to enable the trigger
plate to engage with the plate on the slide.
ABEL & IMRAY,
Agents for the Applicants,
28, Southampton Buildings,
London, W.C.

page_text: We CHARLES JOHN GALLOWAY and JOHN HENRY BECKWITH, both of Manchester,
in the County of Lancaster Engineers, do hereby declare the nature of our
Invention for "AN IMPROVEMENT IN TRIGGER GEAR FOR ENGINE VALVES"
and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :—
In the Specification to a Patent granted to us on the 13th June 1876 N° 2439,
we described trigger gear applied to the admission slides of an engine cylinder, the
trigger in each case being released either at a definite part of the stroke, or at a
part determined by the governor, so as to allow the slide to be pressed back and
to close the admission port. The trigger gear described in the said Specification
consisted of a plate fixed on the slide rod and presenting its edge to another plate
fixed on a bent lever pivotted on the eccentric rod. When the eccentric rod began
its stroke, the lever on it was in such a position that its plate engaged with that
of the slide rod, and consequently, as the eccentric rod moved, the slide rod was
pushed along with it opening the cylinder port, until the lever became so far canted
by the drag of a rod controlled by the governor that the plate on the lever was
raised out of engagement with the plate on the slide rod, and consequently the
latter was left free to be pushed back, closing the cylinder port.
Our present
Invention relates to a construction and arrangement of trigger gear of this kind,
whereby its action is rendered more certain, and its application to various forms
of engines is facilitated.
For this purpose, we arrange the trigger gear as we will describe referring to
the accompanying Drawings, Fig. 1 being a side elevation, Fig. 2 a plan and
Fig. 3 a transverse section of so much of a horizontal engine as is necessary to
illustrate our present Invention. There are two slides to be moved by the rods A
and A' respectively from the eccentrica B and B¹ which are fixed on the crank
shaft C. There are therefore two sets of trigger gear, one for each slide; as these
are similar we will describe one of them, marking corresponding parts of the
other with corresponding letters accented. On the ends of the arms D, which
carry the trigger plate d we pivot a three armed lever E carrying rollers e on
one of its arms, and having its long upright arm jointed to a horizontal arm F,
the end of which is made with an inclined curved slot fas in the ordinary link
motion of a steam engine. The sleeve of the governor G which may be situated in
any convenient position, is linked by a rod g to an upright arm h on a rocking
shaft from which projects a horizontal arm H linked to F which is thus made to
rise or to descend according as the speed of the engine and governor is greater or
less than the normal speed.
In the curved slot f is engaged a pin carried at the top of an upright post K
which is fixed on the eccentric rod. As the eccentric B travels round in its
circular path, the pin at the top of K besides having the to and fro movement due
to the stroke of the eccentric, and consequently accompanying the eccentric and
slide rods while they are engaged together, has an additional movement due to the
angular attitudes which the eccentric rod takes during its stroke, and by this
movement communicated through the slotted link fand arm F to the lever E, this
lever is canted. As its rollers e are moving along fixed guides L, the centre of e
becomes the fulcrum of the lever which in being canted raises the arm D and its
trigger plated disengaging it from the catch plate M on the slide rod and so
releasing the slide permitting it to make its backstroke. The action of the governor
in raising or lowering the arm F brings such a part of the curved slot f in contact
with the pin on K, that according as the speed of the engine exceeds or falls short

page_text: of the normal speed, the disengagement of the trigger plate d and consequent
release of the slide and cut off are effected at an earlier or later part of the stroke.
The guide plates L are made lower towards the right end so as to allow the rollers e
to descend when the eccentric rod is back and thereby to ensure the engagement of
the trigger plated with the catch plate M at the commencement of the stroke of
the eccentric rod towards the left.
We would have it understood that we make no general claim to trigger gear for
engine valves wherein a trigger plate such as d fixed on an arm D mounted on
the eccentric rod is engaged with or disengaged from a catch plate M on the slide
rod, as described in the Specification N° 2439 of 1876 above referred to.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed, we declare that what
we claim is:
--
In trigger gear for engines, in combination with the trigger arms D, the lever E
with its roller e resting on guides L, the arm F with slotted link f engaging a pin
on an upright K projecting laterally from the eccentric rod K and the parts
connecting the arm F to the governor sleeve substantially as and for the purposes
herein set forth.
Dated this 10th day of September 1884
ABEL & IMRAY,
Agents for the Applicants,
28, Southampton Buildings,
London, W.C.