Improvements in and relating to Moving Fire Bars.
Year: 1897

page_text: Date of Application, 20th Mar., 1897
LOOD
L
1000
Improvements in and relating to Moving Fire Bars.
I, ROBERT MACGREGOR, Engineer, of Neilsonton Place, Coursington Road,
Motherwell, N.B., do hereby declare the nature of this invention to be as follows:-
This invention relates to that class of furnaces commonly used in connection with
mechanical stoking of boilers where the fire bars are kept in motion for the
purposes of keeping the air spaces between the bars free from clinker and also
travelling the fuel towards the bridge wall.
This invention consists in providing simple mechanical devices to give the desired
motion to the fire bars and in so constructing the bars that their life is increased
over those at present in use.
In carrying this invention into effect according to one modification as applied
to the furnace of a "Cornish" boiler I proceed as follows:-
On the boiler front, bearing brackets are fixed carrying a horizontal cam shaft
at or about the height of the usual furnace dead plate, and placed on extensions of
these bearing brackets, parallel with the cam shaft, and a short distance out from
it, a second shaft is placed carrying supporting toggle levers upon which the outer
ends of the fire bars rest. Placed on the cam shaft concentric with it and keyed
or fixed to it are a number of deeply grooved pulleys one pulley under the outer
end of each fire bar; and these pulleys have each one small roller rotating on a pin
fixed across their respective grooves while rigidly fixed to the ends of the fire
bars immediately overhead are contact pieces which are acted upon by the rollers
to travel the fire bars in as hereinafter described. Near each end of the cam shaft
are side groove box cams with one rise in each of their grooves, and in these grooves
the roller ends of bell crank levers ride, while the bell crank levers are themselves
pivotted upon the ends of the second shaft and have their other arms or ends nearly
vertical and connected by links to a cross bar moving in slots in the outer portions
of the firebars, the movement of the box cams through these devices putting the.
bars back into the furnace, all as hereinafter described.
The operation of the hereinbefore described mechanism is as follows:-
The cam shaft is slowly turned by suitable gearing and revolves the grooved
pulleys and rollers until these rollers come against the contact pieces on the fire
bars, when owing to the direction of rotation the bars are pulled out for a distance
corresponding with that portion of the rollers path in which contact continues
and these bars are pulled out in pairs, series alternately or in any order desired by
arranging the rollers in the grooved pulleys in the corresponding relative positions.
At a point corresponding with the movement of the last bar or bars the rises in
the grooved box cams operate on the bell crank levers, connecting links, and cross
bar and move all the bars bodily in. While these to and fro movements are taking
place the bars which are free to move over the bridge wall at one end take at the
outer end a vertical oscillating movement, because at that end they rest upon
freely moving vertical toggle levers, riding upon the second shaft.
For the purposes of increasing the life of the fire bars there is dovetailed to the

page_text: inner end which rests upon the bridge wall a separate piece which can be replaced
and the other wearing portion, viz., the contact pieces are also made replaceable.
It is to be clearly understood that these improvements may be applied to other
than mechanically stoked furnaces.
Improvements in and relating to moving fire bars.
I, ROBERT MACGREGOR, Engineer, of Neilsonton Place, Coursington Road,
Motherwell, N.B., 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 that class of furnaces commonly used in connection with
mechanical stoking of boilers where the fire bars are kept in motion for the purposes
of keeping the air spaces between the bars free from clinker and also travelling the
fuel towards the bridge wall.
The invention consists in providing simple mechanical devices to give the desired
motion to the fire bars and in so constructing the bars that their life is increased
over those at present in use.
The methods of carrying the invention into effect are illustrated in the accom-
panying sheet of drawings as follows,-
Figure 1 is a part front elevation of a mechanical stoker arranged on a two flued
boiler of the Lancashire type with the improved bars.
Figure 2 is a part longitudinal section through one flue displaying the mechanism
for moving the fire bars.
Figures 3 and 4 are details to a larger scale of the fire bar mechanism.
In carrying the invention into effect as illustrated according to one modification
and as applied to the furnaces of a "Lancashire" boiler the construction and
operation is as follows:-
On the boiler front A bearing brackets B B are fixed carrying a horizontal cam
shaft C at or about the height of the usual furnace dead plate, and placed on
extensions of these bearing brackets B, B, parallel with the cam shaft C, and a short
distance out from it, a second shaft D is placed carrying supporting toggle levers E
upon which the outer ends of the fire bars F rest. Placed on the cam shaft C
concentric with it, and keyed or fixed to it are a number of deeply grooved
pulleys G, one pulley G under the outer end of each fire bar F, and these pulleys
have each one small roller H rotating on a pin fixed across their respective
grooves I, while rigidly fixed to the ends of the fire bars F and immediately over-
head are contact pieces J which are acted upon by the rollers H to travel the fire
bars in as hereinafter described. Near each end of the cam shaft C are side groove
box cams K, K, with one rise L in each of their grooves M, and in these grooves the
roller ends N, N, of bell crank levers 0 0 ride, while the bell crank levers 0 0 are
themselves pivotted upon the ends of the second shaft D and have their other arms
or ends P, P, nearly vertical and connected by links Q, Q, to a cross bar R moving
in slots S in the outer portion of the firebars F, the movement of the box cams K
through these devices putting the bars back into the furnace, all as hereinafter
described.
The operation of the hereinbefore described mechanism is as follows: -

page_text: The cam shaft C is slowly turned by suitable gearing and revolves the grooved
pulleys G and rollers H until these rollers come against the contact pieces J on
the fire bars F when owing to the direction of rotation the bars are pulled out for
a distance corresponding with that portion of the rollers H path in which contact
continues between each roller H and its corresponding contact piece J and these
bars F are pulled out in pairs, series, alternately or in any order desired by
arranging the rollers in the grooved pulleys in the corresponding relative positions.
In the longitudinal section Figure 2 and the detail Figure 3 a number of holes
for the pins of the rollers H are shown drilled in the flanges of the grooved
pulleys & so that the relative position of the single roller H on each pulley G to
the others may be arranged to produce the required order of withdrawal of the bars
as hereinbefore referred to. At a point corresponding with the movement of the
last bar or bars F out, the rises L L, in the grooved box cams K, K, operate on the
bellcrank levers 0, 0, connecting links Q, Q, and cross bar R and move all the bars F
bodily in. While these to and fro movements are taking place the bars which are
free to move over the bridge wall T at one end take at the outer end. a vertical
oscillating movement, because at that end they rest upon the freely moving vertical
toggle levers E, riding upon the second shaft D.
For the purposes of increasing the life of the fire bars there is dovetailed to the
inner end which rests upon the bridge wall a separate piece U which can be replaced
and the other wearing portion viz., the contact pieces are also made replaceable.
It is to be clearly understood that these improvements may be applied to other
than mechanically stoked furnaces, and also that "Cornish" or other types of
boilers, and furnaces for other purposes may be fitted with the improved moving
bar without departing from the subject matter of the present invention.
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 moving fire bars for boiler furnaces and like purposes in combination; a
slowly revolved shaft with cams acting upon stop pieces on the fire bars to pull the
said bars outwards from the furnace in any desired order, a second shaft parallel
with the first and having bell cranks on its opposite ends operated by suitably
shaped cams on the opposite ends of the first shaft when all the bars are fully at
the length of their travel to force all the bars fully in at one operation by a cross
bar attached to similar arms of the said bell cranks, and toggle levers fixed to the
ends of the second shaft oscillating to and fro underneath the outer ends of the
fire bars to give a rising and falling motion to the said bars; all substantially as
and for the purposes herein before described.
2. The improvements in and relating to moving fire bars substantially as and
for the purposes herein before described with reference to Figures 1, 2, 3, and 4 of
the accompanying drawings.
1
1007
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents.