An Improvement in Fixing Back Bridges, Slab Plates, and Fire Bars for Horizontal Boiler Furnaces.
Year: 1895

page_text: Date of Application, 9th Dec., 1895
Complete Specification Left, 8th Sept., 1896-Accepted, 17th Oct., 1896
PROVISIONAL SPECIFICATION.
An Improvement in Fixing Back Bridges, Slab Plates, and Fire
Bars for Horizontal Boiler Furnaces.
NICHOLAS DOWNING, Ironfounder Clarence Foundry Railway Street Stockton-
on-Tees, do hereby declare the nature of this invention to be as follows:-
The improvement consists in 2 side frames in the shape of a bar which are fitted
below the firebars & are attached to bridge plate by a dovetail joint cast on same
& bolted at the other end to slab plate (which is bolted to firedoor frame) so that
no knees or brackets are required in the furnace, thus dispensing with the old
method of tapping the plates of boiler flue & bolting or screwing knees on to the
sides of furnace to carry the back bridges, slab plates, & firebars.
By the improved method no holes are made in boiler flue & the saving of labour
in fitting is considerable.
The firebars are suspended on a moveable bearing bar near bridge plate, thus
allowing for expansion & contraction of firebars, which was impracticable under
the old method of fixing.
Dated thio 7th day of December 1905
NICHOLAS DOWNING.
An Improvement in Fixing Back Bridges, Slab Plates, and Fire
Bars for Horizontal Boiler Furnaces.
I, NICHOLAS DOWNING, Ironfounder, Clarence Foundry, Railway Street,
Stockton-on-Tees, in the County of Durham, 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 relates to the furnace fittings of horizontal boilers and is designed
to effect an improvement in such fittings in respect of fixing back bridges, slab
plates and the fire bars thereof in their several positions.
As at present constructed to adapt them to the ordinary cylindrical flues of
horizontal boilers the requisite connections between the apparatus comprising the
several parts or fittings of such a furnace and the furnace flue are effected by means of
rivets, bolts or screws inserted through holes drilled or tapped through the boiler
plates and the connection, so effected is not only detrimental to the boiler in
consequence of such holes, but is also rigid and devoid of means for accomodating
the contraction and expansion of the fire bars which are liable to double up
when heated, and further the labour involved in fitting up a furnace in this way
and repairing or removing it is difficult and costly.
The object and result of my invention is to obviate these defects and to provide
an apparatus or mechanical arrangement for fitting into a boiler flue of this kind
which by its construction and the combination of its several parts is secured in
position without the use of knees or brackets rivetted or bolted to the boiler plates,
thus dispensing with the old method of tapping the plates of the boiler flue and

page_text: bolting or screwing knees onto the sides of the furnace to carry the back bridges,
slab plates, and fire bars; and in which provision is made for the contraction and
expansion of the fire bars.
The apparatus or mechanical arrangement is readily inserted bodily into position
and detachably secured there to be withdrawn at any time for examination, repairs
or removal.
Referring to the drawings hereto annexed in which a convenient way of carrying
out my invention is illustrated, it will be found that the improvement consists in
two side frames each in the shape of a bar, which side frames are fitted below the
fire bars and are attached to a bridge plate by a dovetailed joint cast on same and
bolted at the other end to the slab plate. The fire bars are suspended on a
moveable bearing bar near the bridge plate, thus allowing for expansion and
contraction of fire bars which was impracticable under the old method of fixing.
In the drawings,
Fig. 1 is a longitudinal sectional view taken on line of Fig. 2 of a boiler
furnace fitted in position and embodying my improvements.
Fig. 2 is a corresponding plan view thereof.
Fig. 3 is a front elevation of the boiler end, and Fig. 4 a back elevation of the
boiler flue.
Fig. 5 is a sectional view showing the method of fixing short fire bars according
to my invention.
The same letters of reference indicate corresponding parts in all the figures.
a a are the two side frames in the shape of bars which are fitted below the fire
bars and are attached at one end to the bridge plate by a dovetail joint b¹ cast
on same and bolted at the other end to the slab plate c which is supported by
and bolted to a flange d' on the firedoor: frame d. e is a cross bar for holding
down the side frames a a in position at the rear end. The fire bars are suspended
on a moveable bearing bar near the bridge plate b, thus allowing for expansion
and contraction of the fire bars. The bridge plate 6 is detachably secured in
position by wedges g working on pivots so as to be jammed in tight against the
boiler plates in the manner shown in Fig. 4. When these wedges are turned up
as shown in dotted lines, the whole apparatus can be bodily removed, but the
fire bars which may be of the ordinary pattern are also separately detachable in
the usual way.
Fig. 5 shows my improvements as adapted for short fire bars in which a cross
bar fixed in each side frame a is employed for this purpose.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In fixing the back bridge, slab plate and fire bars in the flue of a horizontal
boiler, the arrangement and combination of parts fitted together to be bodily
inserted and detachably secured in position, substantially as and for the purpose
as bereinbefore described with reference to the accompanying drawings.
2. In combination with such apparatus or mechanical arrangement a moveable
cross bearing bar adapted for supporting the fire bars and allowing for the
expansion and contraction thereof as bereinbefore described and illustrated.
Dated this 5th day of Santembar 1906
G. J. CLARKSON,
Chartered Patent Agent,
Stockton-on-Tees, Agent for the Applicant.