Year: 1886

page_text: I, JOHN CRESSWELL BRENTNALL of Norris Hill, Heaton Norris in the County
of Lancaster, Gentleman do hereby declare the nature of this Invention to be as
follows:-
My said invention relates principally to the furnace grates of steam generators
and may be used or applied either independently or partly in combination with certain
improvements in furnaces for which I have made application for Her Majesty's
Letters Patent the 13th day of July 1885 Number 8435. Under my present
invention the longitudinal bars composing the furnace grate are advanced simul-
taneously in sets of two, three or more and retracted in rotation or in groups. The
bars are moved by cams mounted on a shaft in front of the furnace a cam being
provided for each bar. Certain of the bars composing the grate are formed with
cross pieces or pushers at their outer extremities which extend across the ends or
across projections from the ends of one, two or more of the neighbouring bars on
one or on both sides of the said pusher or leading bar. The cams which work the
said pusher bars or leading bars act so as both to advance and retract the said
pusher or leading bars whilst the cams of the other bars are formed so as only to
retract their bars after they have been advanced by the cross pieces on the pusher
or leading bars. Each pusher bar is thus the actuating bar of a group when the
group is being advanced but in retracting the pusher bars return alone the other
bars being brought back singly in rotation or in groups by their separate cams.
In combination with the said reciprocating grate bars I prefer to use the fuel pusher
or shoulder at the ends of the bars as described in my said former application
No. 84358. The said fuel pusher instead of being attached to or formed on each
individual bar may be formed or attached to the aforesaid leading or pushing
bar and be caused to extend over several of the adjacent bars for example over
the group governed by the leading bar to which it is attached or such a fuel
pusher might extend across the full width of the grate and be fixed to all or to a
certain number of the. leading or pushing bars. The bars may be solid and be
spaced differently at different points in the length of the grate so as to vary the
air supply and prevent loss of fuel as described in the said former application or
I may employ duplex bars the air spaces between them being reduced in width to
suit the varying thickness of fuel on the grate. Thus it is evident that as the fuel
travels towards the bridge the thickness of fuel becomes less and therefore requires
.
077

page_text: less air to support combustion I therefore reduce the air spaces in or between the
bars as they approach the back of the grate. The outer sides of the duplex bars
may or may not be reduced. To diminish friction and to prevent access of
dust to the bearings I support the reciprocating bars on toothed or notched segments
which rock on cross bars on bearers beneath the grate. The bars are toothed or
notched similary to the peripheries of the segments so that in working together the
bars or segments always retain their proper relative positions. When a mechanical
stoker is used to feed the herein described furnace grate I provide means whereby
the delivery of fuel from the hopper may be varied without altering the speed of
the hopper roller. It is preferable that the fuel should be delivered when all of the
bars have returned to the front of the furnace and a chamber is formed in the
hopper roller which chamber delivers its contained fuel at the proper time. As it
would be impossible to vary the speed of the hopper roller without delivering the
fuel at times when the bars are not in a position to receive it, I arrange to increase
or diminish the capacity of the fuel chamber in the roller by means of a sliding
bottom or partition which can be raised or lowered by an adjusting screw or cam.
The said adjusting screw may be operated by a worm and wheel from the end of
the roller or by a key or screw-driver or otherwise.. The hopper may thus be
driven from the cam shaft and at the same speed the amount of fuel delivered at
each revolution being determined by the means described. An iron apron may be
hung between the fuel delivering orifice and the front of the furnace so as partly
to shield the hopper roller from the heat. When hand stoking is resorted to this
apron can be raised to allow the fuel to be thrown upon the bars.
DUTTON & FULTON,
1, St. James Square, Manchester,
Agents.

page_text: COMPLETE SPECIFICATION.
Improvements in Steam Generator and other Furnaces.
I JOHN CRESSWELL BRENTNALL of Norris Hill, Heaton Norris, in the County
of Lancaster, 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 and accompanying drawings:-
My said invention relates principally to the furnace grates of steam generators
and may be used or applied either independently or partly in combination with
certain improvements in furnaces for which I have made application for Her
Majesty's Letters Patent the 13th day of July 1885 number 8435.
And in order that my said invention may be properly understood I will now
proceed more particularly to describe and ascertain the mode or manner of
carrying the same into practical effect, reference being had to the annexed sheet
of drawings.
Fig. 1 of the said drawings is a side view of the central bar a of a set of bars a. b.
and c two such sets of three being shown in the plan view Fig. 3. Fig. 2 is an end
elevation of Fig. 1. As has been said the longitudinal bars composing the grate
are advanced simultaneously towards the bridge in the direction of the arrow
(Fig. 1) in sets of two, three or more (in the example in sets of three) and
retracted in rotation or in groups. These movements are obtained from the
cams a, b and c¹ fixed to the shaft d which revolves in suitable bearings in
front of the furnace. The cam a¹ operates the central bar a and imparts a regular
reciprocatory motion thereto, while the cams b¹ and c¹ on each side, operate their
corresponding bars b and c in an outward direction only and at different times.
In my provisional specification I referred to cross pieces or pushers which projected
from certain of the bars, say the central bar a, of each set, these pushers being
intended to carry in the side bars b and c when the central bar makes its inward
stroke. In the arrangement shown in the drawings I have dispensed with the
said pushers on the central bars as the fuel pusher e being made broad enough
to cover each set of three bars is utilized to perform the functions of the said
projecting pushers. It will be evident however that in the absence of the said
fuel pusher or under modified forms of the same the aforesaid pushers would be
retained and employed as described in the provisional specification. The fuel
pusher e is fixed to the central bar a of the set and projects over the bars b and c
on each side. When the three hars are lying in line as shown at Fig. 3 the vertical
limb f of the fuel pusher is in contact with snugs g formed or fixed on the side
bars b and c, so that when the central bar a is pushed in by its cam a¹ acting on
the projection a' the fuel pusher acting on these snugs g takes in the two side bars
also, so that the three bars advance in unison in the direction of the arrow (Fig. 1).
When the central bar bas been pushed in to the full extent, a short dwell takes
place until the continued rotation of the cam a' brings its acting surface against
the projection a³ on the central bar a which immediately begins its return stroke
carrying with it the fuel pusher but leaving the side bars 6 and c.
When the

page_text: central bar a bas moved outward a certain distance the pushing face on the cam 61
comes against its corresponding projection on the bar b which then follows the
central bar. Lastly the pushing face on the cam c actuates the bar c in a similar
manner the three bars being thus drawn out one after another and arranged in line
ready for the simultaneous inward stroke already described. Instead of having
the leading bar in the centre it might be at the side but in any case it would
require to carry the fuel pusher or independent bar pushers if such were used and
instead of having a fuel pusher e to each set of bars as described I might provide
one fuel pusher to extend over the entire width of the grate and fixed to all or to
a certain number of the bars a. The bars a b and c may be solid and be spaced
differently at different points in the length of the grate so as to vary the air
supply and prevent improper combustion or loss of fuel as described in my
aforesaid former application. In the drawings I illustrate what I have in my
provisional specification termed "duplex bars" the said bars being cored out in
the centre as shown at h Fig. 3. It will be observed that the spaces h are wider
.at the front of the grate and narrower at the back the object being to diminish
the supply of air towards the bridge the thickness of fuel on the grate being
ordinarily less at that point than at the front of the grate and therefore requiring
less air. The outer sides of the duplex bars may be reduced in thickness towards
the front so as to increase the space between each bar at that point but in the
drawing such reduction is not shown. To diminish friction I support the
reciprocating bars a b and c upon toothed segments i the teeth of the segments
working in racks ; formed on the lower side of each end of the bars. The
segments i rock upon bearers k and may if preferred be made of a vee shape at
the peripheries as shown at Fig. 4 the racks j, being correspondingly formed. This
formation of the segments and racks tends to prevent lateral displacement of the
bars. Fig. 5 is a sectional view of the lower part of the fuel hopper which
I might employ when my improved furnace grate is stoked automatically. As it
is desirable that the fuel should be dropped upon the bars at fixed intervals that
is to say at the times when the sets of bars have all completed their outward
stroke, the rotations of the feeding drum m with relation to the movements of the
bars should remain constant so that fuel should not be fed until the bars have been
drawn out to receive it. I therefore drive the feeding drum from the shaft d so
as to secure unison of motion with the bars and I increase or diminish the supply
of fuel by increasing or diminishing the capacity of the fuel chamber n, This
result is obtained by fitting the chamber with a sliding bottom o which can be
raised and lowered by a screw p capable of being turned by a screw-driver, box-
.key or other suitable tool introduced through the port q in the outer casing r.
Instead of a screw a cam might be used to raise and lower the sliding bottom o.
To protect the drum at times from the heat of the furnace I may apply a hinged
aprons which can be opened or closed by a handle from without. When hand
stoking is resorted to, the apron s can be moved into the position indicated by
dotted lines so as to allow the fuel to be thrown upon the bars.
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 steam generator and other furnaces arranging the bars in sets of two
three or more bars each set containing a leading bar advanced and withdrawn by
a cam the said leading bar moving the other bars of the set forward on the advance
stroke by means of pushers and leaving them to be retracted by their own cams on
the return stroke substantially as described and shown.
(2) In a furnace grate composed of bars arranged in sets and operated by cams
in the manner set forth providing the leading or pushing bars with projections or
pushers formed on or attached thereto, and arranged to engage with the adjacent
bar or bars on one or on both sides of the leading bars so that as the leading bars
sare advanced by their cams they take in with them the bars governed or embraced

page_text: by the said pushers or projections, the bars thus advanced being left by the leading
bars and retracted in rotation by their own 'cams substantially as described and
shown.
(3) The fuel pusher attached to or formed on the leading bar of each set or on
certain of the same and extending separately over each set or over several sets or
over the entire width of the grate, substantially as described and shown.
(4) The fuel pusher as particularized in the foregoing claim and utilized also as
a bar pusher to carry forward those bars of the set which are operated or governed
by the leading bar of each set substantially as described and shown.
(5) The oscillating antifriction segments for supporting the reciprocating bars
mounted on bearing bars and formed and operating substantially as described and
shown.
(6) The hopper roller with adjustable fuel chamber for automatically stoking or
supplying measured quantities of fuel to the bars the said roller revolving in
constant relative unison with the movements of the bars, substantially as herein-
before described and shown.
DUTTON & FULTON,
1, St. James Square, Manchester,
Agents.