To compensate for the lap always formed on plain side valves,
the slot is not formed across the center s of the eccentric, but is
placed across the center t of the crank shaft e, away from the
center a distance equal to the lap on one end of the valve, so that
the eccentric, when in its central position, will move the valve
just enough to compensate for the lap, while any change of position
to be supplied to the piston during a part of the stroke
corresponding to the extent of the eccentric’s displacement
from its central position.
To shift the eccentric while in motion, I employ a
diagonally-grooved traveler, k, or key with inclined grooves 1
form, ed in its top, the key being fitted to the groove m or seat
in the shaft e, and passing through suitable notches n, cut
opposite the seat in the collars b and c. One side of the slot h,
opposite the seat m, is formed with inclined teeth o, which fit,
the groove’s 1 in the traveler k, and any longitudinal movement
of the traveler therefore causes a transverse movement of the
eccentric between the collars b and c, any transverse movement of
the traveler being prevented by the sides of seat m and by
its fitting the notches in collars b and c.
A clutch ring, p, is fitted loosely to the shaft e, and secured
by a screw or pin, q, to the end of the traveler, which projects
from the collars b,c, and a groove, r, formed in the periphery of
the ring, furnishes the means to move the traveler when the shaft e
is in motion, as is usual with all revolving clutches.
The engine has a seven eight inch bore,
13/8 stroke. The fly wheel is
41/2 in diameter and
7/8‘ face. The crank shaft is one half
inch in the bearing and nine sixteenth inch between the bearings.
The governor is a dummy. The base is 9 inches long and 6 inches
wide. He operated the engine on compressed air for
demonstrating.
The Pipestone is interesting itself. It can be worked the same
as iron and takes a high polish. It is kind of dark maroon
color
By this construction the engine can be reversed without the use
of any parts extraneous to the eccentric and the few fittings
described, and the operation of the engine and its valve is equally
per-feet in whichever direction it revolves, while the facility
with which the stroke of the eccentric can be varied affords the
most convenient means of changing the cut off point of the valve
and adjusting- the supply of steam exactly to work the engine has
to perform. This is especially desirable when the speed has to be
greatly varied, as in the starting, stopping, and backing of steam
vessels, or when the load upon the engine is frequently changed, as
in hoisting, towing’, etc.
It is evident that the operation of ray grooved traveler would
be the same, whatever means are employed to afford the eccentric a
transverse movement on the shaft, and as various devices, such as
dovetailed and rectangular slides, are already in use for such
purposes, I do not limit myself to the exclusive use of the ribs f
and grooves g for that purpose; but
I claim the traveler and eccentric in the following manner:
1. The shifting- eccentric a, provided with toothed slot h, and
applied on shaft e, between fixed collar b and adjustable collar c,
so that its center s is distant from the center t of said shaft an
amount sufficient to compensate equally for the lap of the slide
valve, whether running the engine backward or forward, in
combination with the rectilinear adjustable grooved traveler k and
the clutch ring p, substantially as described.
2. Eccentric a, combined with the ad jus table collar c, fixed
collar to, constructed and applied on shaft e substantially as
described, and having combined there, with the traveler k, as set
forth, and for the purpose described.
In testimony that I claim the foregoing I have hereto set my
hand this 18th day of May, 1879, in presence of two witnesses.
WM. BAXTER
Witnesses:
William L,. Fish,
Thos. S. Crane.
