IMPROVEMENTS IN AND CON- NECTED WITH FANS FOR VENTILATING MINES AND OTHER USES
Year: 1878

page_text: LETTERS PATENT to Graham Stevenson, of Airdrie, in the County of Lanark,
North Britain, Engineer, for the Invention of "IMPROVEMENTS IN AND CON-
NECTED WITH FANS FOR VENTILATING MINES AND OTHER USES."
Slanted the 6th Avomat 1970 and dated the 15th February 1878
PROVISIONAL SPECIFICATION left by the said Graham Stevenson at the
Office of the Commissioners of Patents on the 15th February 1878.
GRAHAM STEVENSON, of Airdrie, in the County of Lanark, North Britain,
Engineer. "IMPROVEMENTS IN AND CONNECTED WITH FANS FOR VENTILATING
MINES AND OTHER USES."
This Invention has principally for its object to render fans employed for
ventilating mines and the parts connected with them more efficient in action, more
durable and reliable, and subject to less inconvenience when requiring repairs than
such apparatus as hitherto made.
The improved fans are also advantageously applicable for blowing or exhausting
air for various purposes besides mine ventilation.
In carrying out the Invention according to one modification two of the improved
fans on separate horizontal shafts are combined with the shafts in the same line, and
ordinarily coupled together, but capable of being driven separately either by direct-
acting steam engines or through belt or frictional gearing. The two fans are
arranged to exhaust the air from a vertical shaft or passage situated between them,
and communicating by separate valve a doors with the central or eye parts of the
fans on the inner sides of the fans.
The valves may be made air-tight when shut by flanges on their edges, dipping
into grooves containing a liquid.
The form of the casing of each fan and of the fan blades, as seen on a section
taken through the axis of the shaft, is that given by curves, which are concave
towards the space between the two fans, so that the air in proceeding from the
centre is first guided towards the outer end of the shaft, next radially outwards, and
Pine I

page_text: finally towards the middle space. In this way an endways pressure on the fan due
to the air entering at the eye on the inner side only is counterbalanced by an
opposite pressure due to the blades delivering the air towards the middle space; or
such counterbalancing pressure may be obtained by giving a twisted or approxi-
nately helical form to the blades or parts of them. The shaft bearing at the eye of
each fan is attached to an open framing by arms, which are twisted in form so as
to offer a minimum resistance to and guide the air entering through such framing
to the fan.
The two fan shafts may be coupled together in various ways, but in one improved
and specially convenient arrangement ordinary coupling discs are formed or fixed
on the adjacent ends of the shafts and are connected by screw bolts, but with a
thickness plate interposed, so that when it is required to uncouple the shafts this
interposed plate can be withdrawn, leaving the shafts perfectly clear of each other
without their having to be moved endways.
With the herein-before described arrangements it is obvious that one of the two
fans can be stopped and repaired whilst the other is kept in motion, the ventilating
action not being interrupted excepting for the few minutes required for unfastening
and refastening the couplings.
By another modification two pairs of such fans are combined, and in this case
when repairs are required only one of the four fans need be stopped at one time, or
at most one pair of them, whilst in any case when a fan is stopped that one or those
continuing to act may be temporarily driven at a higher speed, so that the venti-
lating action may be fully maintained.
For many purposes a single fan constructed in the improved manner herein-before
described will suffice.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Graham Stevenson in the Great Seal Patent Office on the 14th
August 1878.
GRAHAM STEVENSON, of Airdrie, in the County of Lanark, North Britain,
Engineer. "IMPROVEMENTS IN AND CONNECTED WITH FANS FOR VENTILATING
MINES AND OTHER USES."
My said Invention has principally for its object to render fans employed for
ventilating mines and the parts connected with them more efficient in action, more
durable and reliable, and subject to less inconvenience when requiring repairs than
such apparatus as hitherto made.
My improved fans are also advantageously applicable for blowing or exhausting
air for various purposes besides mine ventilation, whilst my improved arrangements
connected with the fans or some of them are applicable with other fans.
In carrying out my Invention according to one modification two fans on separate
horizontal shafts are combined with the shafts in the same line, and ordinarily
coupled together, but capable of being driven separately either by direct-acting
steam engines or through belt or frictional gearing. The two fans are arranged to
exhaust the air from one vertical shaft or passage situated between them, and
communicating by separate valves or doors with the central or eye parts of the fans
on the inner sides of the fans.
When the fans are of my improved construction the form of the casing of each
fan and of the fan blades, as seen on a section taken through the axis of the shaft,
is that given by curves, which are concave towards the space between the two fans,
so that the air proceeding from that space at the centre is first guided towards the
outer end of the shaft, next radially outwards, and finally towards the middle space
again. In this way an endways pressure on the fan due to the air entering at the
eye on the inner side only is counterbalanced by an opposite pressure due to the
blades delivering the air towards the middle space; or such counterbalancing
pressure may be obtained by giving a twisted or approximately helical form to the
blades or parts of them.
The two shafts may be coupled together in various ways, but in one improved
and specially convenient arrangement ordinary coupling discs are formed or fixed on
the adjacent ends of the shafts, and are connected by screw bolts, but with a
thickness plate interposed, so that when it is required to uncouple the shafts this
interposed plate can be withdrawn, leaving the shafts perfectly clear of each other
without their having to be moved endways.
With the herein-before described arrangements it is obvious that one of the two
fans can be stopped and repaired whilst the other is kept in motion, the ventilating
action not being interrupted excepting for the few minutes.required for unfastening
and refastening the coupling.
By another modification two pairs of such fans are combined, and in this case
when repairs are required only one of the four fans need be stopped at one time,
or at most one pair of them, whilst in any case when a fan is stopped that one or
those continuing to act may be temporarily driven at a higher speed, so that the
ventilating action may be fully maintained.
For many purposes a single fan constructed in the improved manner herein-before
described will suffice.
And in order that my said Invention and the manner of performing the same
may be properly understood, I hereunto append two Sheets of explanatory Drawings
to be herein-after referred to, and representing various modifications of my improved
apparatus or arrangements. In these Drawings the same reference numerals are
used to mark the same or like parts wherever they are repeated.
Figure 1, on Sheet 1, of the accompanying Drawings is an elevation of one of my
improved fans as viewed on its inner side, and Figure 2 is a sectional side elevation
of a pair of my improved fans combined together.

page_text: The two fans are on horizontal shafts 1, 2, which are in the same line, being
connected by means of coupling discs 3, 4, formed or fixed on the inner adjacent
ends of the shafts and by the usual coupling bolts; but a thickness piece or disc 5
is interposed between the two coupling dises 3, 4; and when the coupling bolts are
removed this interposed disc 5 can be removed, so as to leave the ends of the shafts
quite clear of each other. This coupling arrangement is shown enlarged in
Figure 7 on Sheet 2 of the Drawings.
In Figure 2 the fans are represented as driven by separate single cylinder steam
engines 6, each carried on a massive bed frame 7, requiring very little in the way of
foundation, and also carrying the inner shell or casing 8 of the fan. The outer shell
or casing 9 of each fan is fixed on the shaft 1, 2, and the fan blades 10 are formed
or fixed on the outer shell 9. Each fan shaft 1, 2, has a bearing 11 at the engine,
and another 12 at the central eye or opening 13 of the inner fixed casing 8, and
this inner bearing 12 is attached to the casing 8 by arms 14, which are twisted in
form so as to offer a minimum resistance to the air, and guide it as it enters the
opening 13.
The peculiar curved form given to the inner and outer shells 8, 9, of each fan, as
shown in the Drawings, causes the horizontal pressures of the air in and on the fan
to balance each other, or approximately so; the outside air pressure tending to press
the central parts of the fan towards the side at which the air enters, whilst the
reaction due to the inward curvature of the shells towards the outer circumference
acts in the opposite direction.
In Figure 2 the two fans are shown as applied at the top of a ventilating
shaft 15. The middle space between the fans is enclosed by a casing 16, and is
divided by a vertical partition 17 in the middle into two compartments, the inlets
to which from the shafts 15 are provided with doors or valves 18. When either fan
is not working the corresponding door 18 is closed, so that the action of the other
fan may be effectively maintained. These doors 18, which are shown enlarged in
Figure 7, are by preference made with flanges on their edges, and these Hanges
when the doors are shut dip down into water contained in channels 19 formed round.
the doorways or valve seats.
Figures 3 and 4 on Sheet 1 of the accompanying Drawings are vertical sections
as at right angles to each other, showing a pair of Guibal fans as arranged according
to my improved system for ventilating mines. The fans are provided with separate
driving details, so that each can be worked by itself.
Figures 5 and 6 on Sheet 2 of the accompanying Drawings are vertical sections
as at right angles to each other, showing the combination according to my improved
system of a pair of ordinary blowing fans. In this example the casing above the
doors 18 is constructed to give passages 20 for the air to both the outer and the
inner eyes of the two fans.
It is not necessary in all cases to fix the coupling between the shafts of the two
fans, nor to place those shafts in the same line, as the two fans will in many cases
work quite well both at once without being coupled.
Having thus particularly described my said Invention and the manner of per-
forming the same, I have to state that I do not restrict myself to the precise details
herein described or delineated, but that what I believe to be novel and original, and
claim as the Invention secured to me by and in terms of the herein-before in part
recited Letters Patent is,-
1. The system of fans for ventilating mines, and for other uses wherein two fans
of any suitable kind and fitted with separate driving apparatus, are arranged in
connection with one shaft, and so as to allow either fan to be stopped without
stopping the other, substantially as and for the purposes herein-before described.
2. The constructing of a fan for ventilating or other use, with an inlet on one side
only, and with the parts shaped to direct the discharge towards the same side as the
inlet, substantially as and for the purposes herein-before described.
3. The arranging of the passages or casings, leading the air to a pair of combined
4

page_text: fans with a partition and doors, arranged substantially as and for the purposes
herein-before described.
4. The making of the doors of the air passages with flanges, dipping into channels
in the seat, and containing a liquid, substantially as herein-before described.
5. The making of the arms carrying the inner bearing of the fan shaft of a
twisted or approximately helical form, substantially as and for the purposes herein-
before described.
In witness whereof, I, the said Graham Stevenson, have hereunto set my
hand and seal, this Twelfth day of August, in the year of our Lord One
thousand eight hundred and seventy-eight.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
GRAHAM STEVENSON. (L.B.)