Improvements in or relating to Engine Valve-Gear.
Year: 1897

page_text: Date of Application, 1st Nov., 1897-Accepted, 8th Jan., 1898
COMPLETE SPECIFICATION.
Improvements in or relating to Engine Valve-Gear.
I, JAMES HENRY LOADER, of Addington House, Addington Grove, Sydenham, in
the County of Kent, Gentleman, 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 which relates to valve-gear is particularly applicable to steam
engines such as are referred to in the specification of prior Letters Patent No. 9363
of 1895, granted to me and relating to the propulsion of vessels of various kinds,
but the gear may be used with equal advantage on other types of direct-acting
engines, its object being the construction of a gear which will operate to give
a slide valve a rapid movement to open the port for cushioning at either end of
the long stroke contemplated for engines such as are referred to in the aforesaid
prior Letters Patent succeeded by a slower further movement to open the port to
its fullest extent for the admission of steam to propel the piston on the return
stroke, the operation of cut off at the same end of the cylinder being initiated
slowing and completed rapidly at the same time as the admission operations occur
at the opposite end of the cylinder.
In the accompanying drawings
Figure 1 is a longitudinal central section of a cylinder to which this valve
gear is applied, showing the piston at one end of its stroke, the valve, ports. and
passages in section and the various levers and details of the gear in the position
they would occupy when the "lead" opening had been completed.
Figure 2 is a view corresponding to Figure 1 except that only the valve and
adjacent parts are shown in section, and that the piston is at the opposite end
of the stroke to that at which it is seen in Figure 1.
Figure 3 is a plan of the apparatus shown in Figures 1 and 2: it indicates
clearly the manner in which the valves of two cylinders disposed in the manner
indicated in the specification of the aforesaid prior Letters Patent are coupled so
as to be controllable by one set of gear such as forms the subject-matter of the
present invention.
Figure 4 is an elevation similar to Figure 2, showing the parts of the gear
in the positions they occupy when it is desired to operate the valve by hand instead
of automatically.
Figures 5 and 6 are sectional elevations corresponding to one end of Figure 1
to indicate the different positions taken by the valve gear and corresponding with
the movement of the piston in different directions as will hereinafter be ex-
plained.
Like letters indicate like parts throughout the drawings.
The valve gear is attached to the cylinder A provided with the usual valve B
contained in a steam chest C. The valve rod B₁ passes right through the steam-
chest C and extends along the whole length of the cylinder A. At each end
it is notched in three places 132, 133 and B on the under side. The mechanism
at each end of the cylinder is similar so that it will be sufficient if that at one end
is described as follows:
_

page_text: A curved "bell-crank" lever D is pivotted on a bracket A¹ at one end of the
cylinder and is connected to the corresponding curved lever at the other end
of the cylinder by a link E, above two parallel guide bars F, which also are
supported by the brackets A¹. At the ends of the shorter arms of the curved
levers D are pins 1)', beneath the valve rod B¹: these pins engage in the notches B²
and B3 and thus the levers are enabled to work the valve as hereinafter explained.
The brackets A¹ have an extension A over the cylinder to which are pivotted
slotted curved levers or cams G which each have a pin G¹ to engage in a notch B
in the valve rod B¹.
On the guide bars F is a rider H with an opening H¹ in it, to enable it to
slide along and operate the curved levers D, and the link E in its movement on
the guide bars F. The rider is connected to the cross-head A5 of the piston rod A
by a rod A6. The guide bars F are slotted at each end at FI: in these slots are
sliders J each of which has a lug J¹ extending into the slot of the curved lever or
cam G adjacent to it, in order to move it and so work the valve rod B in con-
junction with the levers D as will be explained hereinafter. The slider J at
each end of the guide bars is connected by a rod J2 to the slider at the opposite
end, and the sliders J thus connected are so disposed that when one of them has
been moved to produce operation of its lever G it remains above that lever and
locks or blocks it and thereby prevents the occurrence of any further movement of
the lever G and the valve gear until it is shifted by the operation of the companion
slider at the other end of the cylinder.
To explain the action of the gear, suppose the piston A to be in the middle
of the cylinder A travelling towards the end a: in this case the port A7 will be
fully opened for the admission of steam.
The rider H will be exactly above the piston A³. Towards the completion of
the stroke the rider H will pass a curve of the lever D, and will thus force the
lower end of the lever into the notch B³ and partially close the port A7. When
the rider H arrives at the slider J the slotted lever G will thereby be pressed down
and will complete the closing of the port A' and partially open the port As.
Steam will now be admitted at the end a and the motion of the piston reversed.
The rider H will now again pass the same curve of the lever 1), the lower end of
which will consequently become engaged in the notch B³ and complete the
opening of the port A³.
Figure 4 is an elevation showing the apparatus when the automatic gear is
out of action and the hand gear thrown in. This disengaging and hand gear
will now be described:-
--
At each side of the steam chest the valve rod B₁ is hinged at 135 to enable its
ends to be lifted out of gear with the pins D¹ and G¹. For the performance of
this operation a support A¹ carries on a pivot pin L' a lever L having above and
below the valve rod two pins L2, L³. One of the pins preferably the lower one La
extends beyond the lever towards the support K and has rigidly connected to it
and pivotted on the pin L' a handle L. Corresponding apparatus at the other
end is coupled to the devices just described by means of a connecting rod L5
attached to the pin L³.
By moving the handle L into the position in which it is shown in Figure 4
both ends of the valve rod B are lifted clear of the automatic gear and thereafter
the gear can be operated by hand by means of the handle M keyed to the shaft M¹,
which is supported on the bracket A': on this shaft M' is also keyed a lever M²
having above the valve rod a pin M³ so placed that when the valve rod is raised
clear of the automatic gear the pin M³ engages in a notch Be on the upper side
of the valve rod and by moving the handle M the valve rod can be manually
operated by means of the pin M³ and handle M so as to drive the piston backwards
or forwards as desired. If this valve gear be applied to the engine described in
the specification of the aforesaid prior Letters Patent I prefer to fix the support A¹
on the tube therein described as running along the centre of the vessel.
In this case also one valve gear can operate valves of both the companion cylin-

page_text: ders, if to the end of the valve rod nearest the middle of the vessel is fixed (as in
Figure 3) one end of the lever N the other end of which is fixed to the correspond-
ing end of the valve rod on the other cylinder. This lever N is centrally pivotted to a
bracket N¹ on the aforesaid tube as shown in Figure 3, consequently the operation
of one valve either manually or mechanically will effect through the lever N the
operation of the other.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what I
claim is:-
1. In a valve-gear the combination with a valve-rod B' and rider such as H
operated by the piston-rod of two levers such as D and G arranged and operating
substantially as and for the purpose described.
2. In a valve-gear the combination with a valve-rod B¹ and a rider such as H
operated by the piston of curved levers such as D and slotted levers such as G,
a valve-rod notched or slotted as at 132, B3, B4 to engage with these levers, and
sliders J connected to each other and operating as locking devices substantially
as and for the purpose described.
3. In valve-gear of the kind described disengaging-gear and hand driving-gear
arranged and operating substantially as and for the purpose described.
4. A valve-gear of the kind described in which one valve-rod is coupled to
another in such manner that the automatic or hand gear operating the first rod
controls also the other substantially as described.
5. The combination and arrangement of parts constituting the complete valve-
gear substantially as and for the purpose herein before described and illustrated
in the accompanying drawings.
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