IMPROVEMENTS IN BOILER AND OTHER FURNACES, AND IN MECHANICAL STOKING APPARATUS THEREFOR."
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by George Sinclair at the Office of the
Commissioners of Patents on the 11th December 1876.
GEORGE SINCLAIR, of Leith, in the County of Mid Lothian, North Britain.
"IMPROVEMENTS IN BOILER AND OTHER FURNACES, AND IN MECHANICAL STOKING
APPARATUS THEREFOR."
This Invention relates to the class of furnaces having movable fire bars, and com-
prises improved arrangements of such bars and their moving mechanism, together
with an improved form and arrangement of bridge, and improvements connected
with the feeding hopper.
In carrying out the Invention the movable bars are fixed together in pairs, and
there may be one or more fixed bars between each pair of movable bars and the
next; the bars rest on rollers held by transverse bearers, and the front ends of the
bars extend under and beyond a hopper, and form the bottom of such hopper, and
they are moved inwards and outwards, but without rising or falling, by means of a
transverse horizontal shaft.
In one modification this shaft has fixed on it a number of discs, bearing pins,
which may be adjusted at distances from the centre to suit the extent of motion to
be given to the bars; each pair of bars has connected to its front end links which
pass some over and some under the shaft, and which are formed with notches to
engage with the pins on the discs. Each pin when moving through the upper part
of its course engages with an upper link and moves the bars in one direction, and
when passing through the lower part of its course it engages with the lower link
and moves the bars back again. The pins are so placed on the different discs as to
make the pairs of bars move alternately in opposite directions, or they may be
placed so as to move the bars in any other advantageous way as regards the order
of the movements of the several pairs of bars.
A shaft formed with cranks or
eccentrics may be substituted for the shaft with discs, and the cranks or eccentric
journals or pins may be connected to the bars by links, or may work in slots formed
in the ends of the bars or in pieces attached thereto.
The hopper is made with a vertically sliding and adjustable door on its inner
face, whereby the depth of fuel passing out of the hopper upon the fire bars may
be regulated, and the bottom of this door has flaps hinged to it and weighted or
connected to springs to make them bend to keep the vertical position, but allow
any lumps of coal larger than the average to get out on turning them inwards.

page_text: The front plate of the hopper is made removable so that hand stoking may be em-
ployed when required.
Å flying bridge, as it may be termed, is fixed across the fire bars at some distance
forward from their inner ends, such bridge having the usual space above it for the
passage of the flames and gases from the forward and main part of the fire, whilst
there is sufficient space between its bottom or under side and the top of the fire
bars to allow a certain thickness of the partly consumed fuel to pass under it
and become completely consumed at the inner side of the bridge.
An important object of this arrangement of the bridge is to maintain a sufficient
depth throughout the main part of the fire and quite up to the bridge without
allowing fuel that is not quite consumed to descend at the bridge into the ash pit.
The flying bridge may be made of fire-brick or it may consist of a water casing or
tube connected at each end of it, that is, at each side of the furnace space to the
main water space of the boiler.