Improvements in mechanical STACIO I
Year: 1898

page_text: Improvements in mechanical STACIO
I, FREDERICK WILFRID SCOTT STOKES, of 32, Victoria Street, Westminster, S.W.,
Civil Engineer, do hereby declare the nature of this invention to be as follows:-
My invention relates to that form of mechanical stoker in which small quan-
tities of small coal are from time to time thrown over the surface of the fire.
The apparatus may be conveniently described under the following heads:-
(a.) The fire bars and actuating mechanism.
(b.) The shovel and its mechanism.
(c.) The feed, hopper, &c.
(a.) The fire bars are mounted so as to be capable of a to and fro motion. A
shaft driven from overhead gear is placed in front of the furnace, and arranged
with cams, or eccentrics, two to each bar. One of each pair of cams imparts
a horizontal motion to the bar, and the other a vertical one, the end of the bars
being suitably shaped to embrace the cams. The other end of the bars is carried
by a cross bar, and a further set of cams mounted on a shaft, carried on bearings
bolted to the side of the flue. Two or more of the bars engage with special
cams, so arranged that as the bar travels forward, it causes the shaft with the
cams to partly revolve in such a way, that the bars which are travelling back are
at a higher level than those which are coming forward, the front cams imparting
a similar vertical movement to the front of the bars.
Thus the whole of each bar is slightly lifted up on the backward stroke, carry-
ing the fire with it, until the end of the stroke is reached, when it sinks on to the
fixed supports, and returns at a lower level.
The bars are arranged so that adjacent bars are travelling in opposite directions.
A jet of steam is arranged between the bars near the front, in the usual way.
A hinged flap, worked by a chain is provided under, the end of the bars for
the withdrawal of the clinker.
In cases where forced draught is advisable, I make the bars abnor-
mally deep, and place a water trough underneath for the purpose of converting
the space between each pair of bars into a sealed chamber into which I force air,
or a mixture of steam and air in any convenient manner.
The trough is so arranged that the ashes may be readily removed without
stopping the blast.
(6.) The shovel, as I prefer to arrange it, is mounted on two radial arms carried
on a shaft above. Near the middle of this shaft is keyed a short lever, which is
worked by a cam on the driving shaft above. This cam has projections of vary-
ing length so as to impart different travels to the shovel.
The shovel is maintained in its forward position, except when controlled by
the cam, by a short lever and rod in connection with a spring in a case (having
adjustable ends) bolted to the side of the apparatus.
The buffing, or recoil motion, of the shovel, is taken up by two springs con-

page_text: The shovel E is mounted on levers G¹ one on each side of the box, which are
carried on a shaft on the top of and outside the box, so as to reduce the wear and
tear. The shovel is maintained in its forward position, except when controlled
by the cam arms F, by a short lever and rod Q in connection with a spring in a
case R. This case is bolted to the box and is provided with adjustable ends or
caps for regulating the springs.
The buffing, or recoil, motion of the shovel is taken up by two springs, one
behind the other, contained in the case R, one a weak one of flat cross section,
and the other a short powerful one. The weak spring is completely closed up
when buffing, and then acts as a distance piece only. At other times it keeps
the strong spring in position and prevents jar.
The shovel, with its gear, is mounted in suitable castings with bearings,
doors S S and other provisions for the feed motions and hopper.
The whole apparatus is mounted on a suitable furnace front H with door I for
hand firing and attention as and when required.
Suitable provision is also made for admission of air above the fire through
the holes K in the front H, either by natural draught or by forced draught by
means of a steam jet or other suitable arrangement, in which case a short length
of pipe of suitable shape is connected with the holes, so as to deliver the air
where it is needed over the fire.
In order to reduce the noise, when steam jets are used, I prefer to draw the air
from a double front, a flue or nearly closed-in chamber, in which the air may
become heated, as well as the vibration deadened.
The necessary motion to the mechanism is preferably given by worms and
worm wheels L driven from an overhead shaft by means of rope and speed
pulleys N, with loose pulley O for stopping the machine, and the hand wheel P
for working the parts by hand.
The feed hopper M is of any convenient shape and capacity, and is preferably
fitted with a screen to exclude large pieces of coal or foreign matter likely to
strain the feed mechanism.
The fire bars T as I sometimes prefer to make them, are mounted on fixed
cross pieces U back and front. A shaft V, driven from the overhead gear, is
placed in front of the furnace and arranged with cams or eccentrics W W two
to each bar. One of each pair of cams imparts a horizontal motion to the bar,
and the other a vertical one, the end of the bars being suitably shaped to embrace
the cams.
At the other end of the bars is arranged a further set of cams,
mounted on a shaft carried in bearings bolted to the sides of the flue. Two or
more of the bars engage with special cams W' on the shaft so arranged that as
the bar travels forward the projection T engages with the projection W" and
causes the shaft to partly revolve in such a way that the bars which are travelling
back are at a higher level than those which are coming forward, the front
cams W W imparting a similar vertical movement to the front of the bars.
Thus the whole of each bar is slightly lifted up on the backward stroke carry-
ing the fire with it, until the end of the stroke is reached, when it sinks on the
fixed supports, U, and returns at a lower level.
The bars are arranged so that adjacent bars are travelling in opposite directions.
The ashes and clinkers gradually feed along the bars and fall over the end.
A clinker door is arranged so as to open for the removal of the clinkers and
ashes.
•
A steampipe Y with small holes in it causes currents of air and steam to pass
between the bars into the burning fuel.
In cases where forced draught is advisable, I make the bar T abnormally
deep, see Figure 3, and place a water trough z underneath for the purpose of
converting the space between each pair of bars into a sealed chamber into which
I force air, or air and steam in any convenient manner.
The trough Z is so arranged that the ashes and clinkers may be removed
without stopping the blast, owing to the water seal.