CERTAIN IMPROVEMENTS IN ENGINES ACTUATED BY STEAM OR OTHER ELASTIC FLUID
Year: 1872

page_text: PROVISIONAL SPECIFICATION left by John William Melling at the
Office of the Commissioners of Patents, with his Petition, on the
5th March 1872.
I, JOHN WILLIAM MELLING, of Birkett Bank, Wigan, in the. County
of Lancaster, Engineer, do hereby declare the nature of the said
Invention for "CERTAIN IMPROVEMENTS IN ENGINES ACTUATED BY STEAM OR
OTHER ELASTIC FLUID," to be as follows:-
The object of this. Invention is for the purpose of regulating the
position of admission or expansion valves and cut-off gear, and it
consists in the first place in fitting on a shaft or spindle that is in
connection with the valves or cut-off gear a toothed wheel or wheels.
At the side of the wheel or wheels a bar or frame is made to vibrate, on
which are mounted two catches that can act on the teeth of the wheel
or wheels when required. The bar or frame has a reciprocating
movement communicated to it from any convenient part of the engine.
On the side of the bar or frame is carried a plate or guard in such a
way as to be free to change its position within fixed limits. The guard
moves along with it and fits under the catches to keep them from acting

page_text: on the teeth of the wheel or wheels. On the guard are two or more
shoulders or projections for the purpose of arresting its motion, also two
shoulders for restoring it to the mid position. Over the guard, centred
on any convenient fixture, are two hooks supported by a lever pivoted on
the same or other centre; to this lever the governor rod is connected.
When the engine is running at the required speed the governor holds
the hooks so as to clear the projections on the guard; when running too
fast or two slow one or other of the hooks is lowered into the path of
one of the projections on the guard and arrests its movement; this allows
one of the catches to drop into the teeth of the wheel which is thus
propelled in the required direction to admit more or less steam on the
return stroke; the motion of the guard is arrested by a fixed projection
before the catch frame has completed its stroke and the catch is again
drawn on to the guard. ·
The guard may have any desired number of shoulders for the hooks
to act on, so as to allow the catches to come into action at any part of
their stroke, this depending on the position in which the governor holds
the hooks. When the engine is running too quick one hook arrests the
guard in its movement in one direction, and when too slow the other
hook stops it in the other. In place of hooks two studs may be used to
arrest the movement of the guard plate. In place of having a guard
with projections carried on the catch frame and moving along with it, a
guard may be used on which are formed two or more steps along and up
and down which the catches can slide; the steps are to allow the catches
to come into gear with the toothed wheel sooner or later, according to
the position of the guard. The guard may be pivoted on any convenient
fixture and its position regulated by having attached to it a lever one
end of which is held by the governor. Attached to and vibrating with the
catch frame is a plate with its inner edges formed into shoulders or
steps; when the plate is near the end of its stroke one or other of these
shoulders comes into contact with a projection on the lever that is held
by the governor rod and determines its position, or the stepped piece
may be on the governor lever. When the engine is running at the
required speed the catches are kept from acting on the wheel by the
guard being forced into mid position; the governor is then holding the
lever so that the projection on it is only just reached by the shoulders in
whose path it is, but if the lever is raised or lowered it then comes into
the path of another shoulder which pushes it into a position that allows

page_text: one of the catches to act on and turn the wheel during a portion of its
stroke; when the projection on the lever is brought into the path of the
extreme shoulders it allows the catches to act during the whole of their
stroke, thus altering the position of the valves or expansion gear to a
greater extent. The position of a toothed bar that is is connection with
the cut-off gear may be adjusted by having a sliding block to which is
given a reciprocating movement working over or at the sides of it, and
on which are centred two catches; the catches are supported at one end
by a guard plate mounted on the sliding block; on the guard are
projections by which it is arrested in its movements as before described.
Or the catches may be controlled by a stepped guard that is centred on a
pin in any convenient fixture, and which has its position fixed by a plate
with shoulders formed on it that is fixed on the sliding block, and which
comes into contact alternately with the ends of a double lever or two
hooks that are held by the governor at one end and attached to an elbow
arm of the guard at the other. The position of the guard is determined
by those shoulders on the plate in whose path the lever or hooks is held
by the governor, as before described.
Another arrangement is to use double ended catches carried by
independent frames. At the end or side of each frame is a projection by
which it may be supported by a lever that is held by the governor and
on which are formed two or more shoulders. At the side of the catch
frames vibrates a double ended lever, one end of which acts on one
catch the other on the other catch. When the engine is at the required
speed the frames are supported on the ends of the levers to which the
governor rod is attached, in which case the vibrating lever only moves
them slightly at the extremities of its stroke, but if the engine is
running too fast or too slow one or other of the levers is partially
withdrawn, which allows the frame to fall on to a lower shoulder; one
end of the vibrating lever on its upward movement then comes into
contact with the long end of the catch, causing the short end to turn
into the teeth of the wheel, then as the movement is continued the
wheel is partially turned round, the catch frame is then lowered on to
the shoulder again, where it is left by the vibrating lever; the long end
of the catch which is made of sufficient weight being then unsupported
turns on its pivot and withdraws the short end out of gear with the
wheel, where it remains until the vibrating lever in its return stroke acts
on it again as before.

page_text: Instead of a toothed wheel and catches a friction wheel and friction
palls may be used.
The governor may so withdraw either of the levers that the catch
frame shall not be supported by any of the shoulders on. the lever, then
the vibrating lever causes the catch to act during the whole of its stroke.
Or in place of the governor levers catching under projections at the
ends or sides of the frames, they may catch under pins or pro-
jections at the sides of single ended catches to support the catch and
frame. In this case the catches are held so that when one is required to
act it is first put into gear with the wheel, then its support is withdrawn,
which, causes it to fall within reach of the vibrated lever; this in its
upward movement comes into contact with some part of the catch frame.
and thus turns round the wheel.