Improvements in the Construction, Arrangement, and Combination of Rotary Apparatus for the Propulsion. Suction, and Move- ment of Air for Ventilating, Blowing, and other Purposes, Anplicable also for the Movement of Fluids and Gases.
Year: 1887

page_text: Date of Application, 21st Feb., 1887
Complete Left, 21st Nov., 1887
Complete Accepted, 23rd Dec., 1887
Improvements in the Construction, Arrangement, and Combination
of Rotary Apparatus for the Propulsion. Suction, and Move-
ment of Air for Ventilating, Blowing, and other Purposes,
Anplicable also for the Movement of Fluids and Gases.
Improvements in the Construction, Arrangement, and Combination
of Rotary Apparatus for the Propulsion. Suction, and Move-
ment of Air for Ventilating, Blowing, and other Purposes,
Applicable also for the Movement of Fluids and Gases.
I CLARENCE WILLIAM CROSSLEY of St. Marys Chambers 14 St. Mary Axe in the
City of London and County of Middlesex, Engineer and Manufacturer do hereby
declare the nature of this invention to be as follows:-
The object of my invention is to compel the air or other medium, as far as possible,
to pass through that part of the area of the whole apparatus (fan or propeller) where
the rotary action of the apparatus gives the greatest speed to the air or other medium.
This object I attain by an improved form of apparatus and I also by certain
arrangements and dispositions of apparatus hereinafter mentioned obtain a more direct
and equal delivery of the air or other medium.
In this specification I shall for greater simplicity of description mention my
invention as used for a Ventilating fan or Air-propeller for the movement of air-
but without confining myself solely to that use. It may also be used for Water,
Gases etc. Generally speaking it will be found that the air delivered by a fan
acquires its greatest speed on a circle having a radius equal to about two-thirds or
seven-tenths the distance between the centre of rotation and the extreme periphery of
the fan. This circle I call the circle of greatest work or effort, and the part of the
blades or wings of a fan, which is the same distance from the centre of rotation as is
the circle of greatest work, I call the centre of work of those blades.
If the blades or wings of a fan be bent or inclined away from the direction of
rotation, the air acted upon by the blades is really "wedged-up" from the centre of
rotation and thrown off at the tips of the blades, unless there is a surrounding cylinder
or the like to prevent its escape in a radial direction. If on the contrary the blades
are bent or inclined in or towards the direction of rotation, then the air is driven
from the tips of the blades towards the centre of rotation where the speed is very
small. Each of these directions of bending or inclination therefore has its

page_text: disadvantage-the one throwing the air off radially and the other driving it towards
that part where it loses speed. Nevertheless, both these movements of the air by the
blades are natural ones, and obtained by a comparatively small expenditure of power
and I make use of them in the construction of my improved apparatus for the object
mentioned in the beginning of this specification.
I form the blades of my improved apparatus in the following manner :-Supposing
the area of the fan to be divided into two concentric portions by a circle at about two-
thirds or seven-tenths the radius measured from the centre of rotation. This circle
will be practically the circle of greatest work of the fan. The blades may be simple
rectangular pieces of metal or the like fastened to a boss, hub, or centre: from their
place of attachment to the boss, I bend or incline them away from the direction of
rotation & this backward bending or inclination I maintain until the blades about
reach the circle of greatest work: from this point I bend the blades in or towards the
direction of rotation and consequently in just the opposite direction to that of the lower
part of the blades. Besides this bending or inclination of the upper & lower part of each
blade respectively towards and away from the direction of rotation I also place than
at a constant or varying angle to the axis of the shaft or spindle of the apparatus.
Whether the angle be a constant or varying one it should be such, that at the
circle of greatest work it gives the maximum amount of propelling force without
offering an excessive or counterbalancing resistance to the passage of the blades
thro' the air. Probably an angle of about sixty degrees from the plane of the front
of the apparatus is as good as any, but it would necessarily have to be arranged to
suit the speed and amount of air to be moved by the fan. When the inclination of
the blade to the axis of the shaft is a varying one, it would be made comparatively
slight at or near the boss, & gradually increased until it reached the circle of greatest
work, where its angle would be some sixty degrees from the front plane of the
apparatus; in the same manner the upper part of each plane would be at a
comparatively small angle at the circumference & gradually increased until it reached
a similar angle (on the circle of greatest work) to that of the lower part of the
blade at that point.
By
The back & front edges of the blades may be perpendicular to, or form an angle
with, the axis of rotation & this angle may be greater or less than a right angle.
this formation of blade the air is, by the backward bend of the lower part of the blade,
wedged-up from the centre towards the circle of greatest work and at the same time
moved in an axial direction by the angle of the blade: during this movement of the
air by the lower part of the blade, it is also driven from the periphery towards the
circle of greatest work by that part of the blades which is bent towards the direction
of rotation and at the same time it is also moved axially by the angle given to the
blade for that purpose. In other words the upward tending air and the downward
tending air meet at the circle of greatest work, at which spot they receive their
maximum thrust forward by the combined action of the greatest speed at this part of
the area and of the axial movement given by the angle or twist of the blades.
The apparatus is suitably attached to a shaft or spindle and revolved by any
convenient or suitable means.
In order to avoid the air being thrown towards one side, as it is apt to be by all
revolving planes which are placed at an angle to the axis of rotation, I place two or
more fans or propellers (of opposite angles or pitches as regards the axis) behind or
in front of one another, and revolve them in different directions, so that the side
work of the fan or propellers revolving in one direction will counteract the side work
of the fans or propellers revolving in the opposite direction and thus propel the air in
a line, nearly, if not quite, parallel to the axis. When using three fans or propellers
I sometimes make the two outside ones revolve in one direction and the middle one
in the opposite direction. The outside ones can be so joined together that by fastening
one of them to a shaft (which may be a tubular one surrounding the shaft of the
middle fan) this shaft will turn both of the outside fans or propellers. In order to
obtain a more equal discharge or delivery of the air or other medium, I place two
or more fans or propellers behind or in front of one another as just mentioned,

page_text: but instead of having them all of the same diameter, I make them all of different
diameters. By this arrangement the circles of greatest work of the various fans or
propellers are not all at the same distance from the axis or centre of rotation, & thus I
practically do away with a localized circle of greatest work so far as the whole
combination is concerned. I obtain, in fact, an apparatus equal in diameter to the
largest of the set of fans or propellers used, and giving an equal discharge from the
whole of its area, owing to the best work of each fan being done at a different part
of the area of the whole apparatus or combination. The fans or propellers of this
arrangement may (but not necessarily) be placed so that the air etc., moved by the
blades of one fan, is not thrown on the backs of the blades of another, but delivered
through the space between the blades.
The fans may be of opposite angles and different pitches, and revolved in different
directions for the purpose of destroying the side work mentioned in the previous
paragraph.
Any or all of the above described fans, propellers, arrangements or combinations,
may be wholly or partly encased in, or surrounded by a ring, cone, or cylinder,
revolving or remaining stationary.

page_text: Improvements in the Construction, Arrangement, and Combination
of Rotary Apparatus for the Propulsion, Suction, and Move-
ment of Air for Ventilating, Blowing, and other Purposes,
Applicable also for the Movement of Fluids and Gases.
I, CLARENCE WILLIAM CROSSLEY of St. Mary's Chambers 14 St. Mary Axe in
the City of London & County of Middlesex, Engineer 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 :-
The objects of my invention are, by improved construction of blade to compel the
air or other medium, as far as possible, to pass through that part of the area of
the whole apparatus fan or propeller where the rotary action of the apparatus gives the
greatest speed to the air or other medium, and by certain constructions arrangements
and combinations of apparatus two or more sets of blades fans or propellers as
hereinafter mentioned, to obtain a more direct and equal delivery of the air or other
medium.
In this specification I shall for greater simplicity in description mention my
invention as used for a Ventilating fan or Air-propeller for the movement of air-
but without confining myself solely to that use as, it may also be used for moving
water, gases etc.
Speaking generally it will be found that the air or other medium delivered by a fan
or propeller attains its greatest speed on a circle having a radius equal to about two-
thirds or seven-tenths the radius of the fan or propeller measured from the centre of
rotation towards the periphery of the apparatus. The circle where the speed is
greatest I call the "circle of greatest work or effort" and the part of the blades or
wings of an apparatus which is the same distance from the centre of rotation as the
circle of greatest work, I call the "centre of work" of those blades.
If the blades or rings of a fan be bent or inclined away from the direction of
rotation, the air acted upon by the blades is really "wedged-up" from the centre of
rotation and thrown off at the tips of the blades, unless there is a surrounding
cylinder or the like to prevent its escape in a radial direction. If on the contrary
the blades are bent or inclined in or towards the direction of rotation, then the air or
other medium is driven from the tips of the blades towards the centre of rotation
where the speed is very slow.
Each of these directions of bending or inclination therefore has its disadvantage
the one throwing off the air radially and the other driving it towards that part where
it loses speed these movements of the air by the blades are however natural ones
and I use both of them in the construction of my improved apparatus.
The apparatus may have as many blades as can be conveniently used, fixed to a
centre, boss or hub. The blades may be madeof sheet metal or the like: they may be
joined up from several pieces, or they may be pressed out of one or more pieces or
they may be cast separately, or together with the boss.

page_text: Each blade from the boss outwards bends, curves or inclines away from the
direction of rotation and this backward bending, curving or inclination is maintained
until the blades about reach the circle of greatest work above mentioned from this
point they bend, curve or incline in or towards the direction of rotation and con-
sequently in just the opposite direction to that of the lower part of the blade. Besides
this bending, curving or inclination of the upper and lower part of each blade
respectively towards and away from the direction of rotation the surface of each must
be at an angle to the axis of rotation. Whether this angle be a constant or varying
one it should be such, that at the circle of greatest work it gives the maximum amount
of propelling force without offering an excessive or counterbalancing resistence to
the passage of the blades thro' the air or other medium. An angle of about thirty
degrees from the plane of the front of the apparatus, is perhaps as good as any, but
it would necessarily have to be arranged to suit the speed and amount of work
required to be done by the apparatus.
When the inclination of the blade to the plane of rotation and to the axis of the
apparatus varies, it would be made of a comparatively small angle at or near the boss
and gradually increased until it reached the circle of greatest work where its angle
would be some thirty degrees (more or less) from the front plane of the apparatus:
in the same manner the upper part of each blade would be at a comparatively small
angle at the periphery and gradually increased until it reaches-on the circle of
greatest work a similar (but not necessarily exactly the same) angle to that of the
lower part of the blade at that point.
Instead of making the two parts meet so abruptly at this point as to come sharply
together, the two parts may be so curved that the lower part of the upper portion of
the blade and the upper portion of the lower part may run gently into each other.
In some cases it may be advisable to make them meet a little above or below the circle
of greatest work.
The back and front edges of the blade may be perpendicular or inclined to the
horizontal projection of the axis of rotation and this inclination may be greater or less
than a right angle. The extent to which the back and front edges of the blades incline,
curve or bend away from or towards the direction of rotation may differ from each other.
By the formation of blade above described the air or other medium is, by the
backward bend of the lower part of the blade, "wedged up" from the centre towards
the circle of greatest work and at the same time moved in an axial direction by the
angle of the blade: during this movement of the air by the lower part of the blade,
it is also driven from the periphery towards the circle of greatest work by that part
of the blades which is bent towards the direction of rotation and at the same time
it is also moved axially by the angle or twist given to the blade for that purpose.
In other words the upward-tending air and the downward-tending air meet at the
circle of greatest work at which spot they receive their maximum thrust forward by
the combined action of the greatest speed at this part of the area and of the axial
movement given by the angle or twist of the blades.
The apparatus is suitably attached to a shaft or spindle supported in any suitable
manner & revolved by any convenient means.
For simplicity in making I sometimes construct an apparatus as follows. To a boss
or hub I attach a suitable number of blades each of which is inclined, bent or
curved towards the direction of rotation and behind or in front of these I place
another set of blades inclined or bent away from the direction of rotation and each set
of blades continues its respective backward or forward inclination &c. (as regards the
direction of rotation) from the boss to the periphery. Each blade is also so shaped,
and fixed at such an angle to the plane of rotation that it will have a propelling effect
axially.
By this arrangement the air is driven towards the periphery by one set of the
blades and towards the centre of the apparatus by the other set of blades and at the
same time it is propelled axially by the angle, twist or other shape given to the blades
for that purpose. In this way the apparatus will deliver the air at a more equal speed
at the different parts of the area of the apparatus and by each set of blades rotating

page_text: in the same direction (and therefore without the necessity of using special means
for driving then in opposite directions) a somewhat similar result will be obtained as
from the combining of two or more sets of blades revolving in different directions as
hereinafter described. As regards the blades which are bent away from the direction
of rotation they will obviously (as already mentioned) throw off the air more or less
at the tips. To obviate this, either both sets of blades can be surrounded by a drum,
cylinder or the like or only that set which throws off the air radially need be so
surrounded, the one with the forward inclined or bent blades being left open and
without anything round the periphery: another way would be to attach a piece of
sheet metal of suitable shape to the periphery of the blades with the forward bend, in
such a manner that it may cover the periphery of the backward inclined blades and
prevent the air going off there: or simpler still the tips of the backward inclined
blades may be turned over for the same purpose. Of course any other device may be
used to prevent the air being thrown off radially by this set of blades.
More than two sets of blades can be used in a manner similar to what I have just
described & they may have different diameters, be placed at different angles to the
plane of rotation and may be bent, curved or inclined away from or towards the
direction of rotation at various rates of inclination, etc.
Each of the blades of the various sets used in the above manner may have a plate
or piece of sheet metal attached to its leading edge as and for the purpose described
in the latter part of this specification.
It is obvious that a separate boss may be used for each set of blades instead of
placing them on one long boss.
The above described combined sets of blades would all revolve in the same direction.
In order to avoid the air being thrown towards one side, as it is rather apt to be,
by all revolving planes which are placed at an angle to the axis of rotation, I place
two or more apparatus, fans or propellers, of opposite angles or pitches, behind or in
front of one another and revolve them in different directions, so that the side work of
those revolving in one direction, will counteract the side work of those revolving in
the opposite direction by this arrangement the air is propelled more parallelly to
the axis. When using three apparatus fans or propellers, the two outside ones
may be revolved in one direction & the middle one in the opposite direction. The
outside ones can be so coupled or joined together, that by fastening one of them to a
shaft (which may be a tubular one surrounding the shaft of the middle fan) this shaft
will turn both of the outside apparatus, propellers or fans.
In order to equalize the dicharge or delivery of the air, etc., I place two or more
apparatus, fans or propellers behind or in front of one another as just described, but
instead of having them all of the same diameter I make them all of different diameters.
The circles of greatest work of the various apparatus, fans or propellers will then
not all be at the same distance from the axis or centre of rotation and thus a localized
circle of greatest work is, (so far as the whole combination is concerned), practically
done away with. In fact an apparatus is thus obtained equal in diameter to the largest
of the set of apparatus, fans or propellers used & giving a nearly if not quite equal
discharge from the whole of its area, owing to the best work of each fan being done
at a different part of the area of the whole combination. When the fans, apparatus or
popellers forming this arrangement are all revolved in the same direction they may be
placed so that the air &c. moved by the blades of one fan is not thrown on the backs of
the blades of another, but delivered thro' the spaces between them.
It may sometimes be better not to use the whole of each of the blades of an
apparatus, fan or propeller whether used singly or in any of the arrangements or
combinations, but only that portion of each blade which is immediately above and
below the circle of greatest work of each fan. The portions thus used would be
supported at the proper distance from the axis, in any suitable manner, such as by a
bar or rod in the middle (when they would resemble the "fly" or "fan" of a clock)
or they may be supported by more than one rod or the like, or they may be attached
to rings, as may be found most desirable or convenient and best suited to their
particular work."

page_text: By thus using only a portion of the blade, the more useless part of each (that
nearest the centre of rotation) is cut away and as when using the complete blade there
is only about one third of the radius above the circle of greatest work (and that
part of the blade is of far greater value for propelling purposes than any other part)
it is hardly necessary to have more below the circle of greatest work where every
inch it gets nearer the centre of rotation it decreases in propelling power and takes
a disproportionate amount of driving power for producing whatever work it may do.
The portions of blades mentioned might be arranged to slide up and down the rod
or rods &c., so as to allow of placing them at different distances from the axis of
rotation. The fans or propellers may be of opposite angles or different pitches &
revolved in different directions for the purpose of destroying the side work mentioned
above.
Any or all of the apparatus, arrangements or combinations constructed in
accordance with this invention may be wholly or partly encased in or surrounded by
a ring, cone, cylinder or the like, revolving or remaining stationary.
The accompanying drawings only shew a blade constructed as mentioned first in
this specification as having, in one & the same blade, an inclination or bend away from
& towards the direction of rotation: no drawing will be required to explain so simple
a matter as putting two sets of blades behind or in front of each other, one set being
bent (from boss to periphery) away from & the other towards, the direction of
rotation as described in connection with the second method of construction mentioned
in this specification. Neither will a drawing be necessary to explain the arranging
of two or more apparatus, fans, &c. behind each other of different angles &c. and
revolving in different directions or to explain the combining of two or more apparatus,
fans, &c. behind or in front of each other whether all of different diameters &
revolving in one direction or of different diameters & revolving in different directions.
The drawings here given do not shew the many modifications which can be made in
a blade constructed as first mentioned & which can be made therein without departing
from the invention.
:
Fig. 1. shews a boss, hub or centre A and a blade Z Y X if the blade be bent,
curved or inclined away from the direction of rotation indicated by the arrow B. the
air, &c. will be wedged-up the blade from the centre in the manner previously
described & about as shewn by the small arrows C. If the saine blade be revolved in
the opposite direction, which is equivalent to using a blade having an inclination in
the direction of rotation as indicated by the arrow D, the air is then driven down
towards the centre of rotation, somewhat as shewn by the small arrows E. The centre
of work of the blades will be at about two-thirds or seven-tenths the radius from the
centre of rotation as before described & situated on a circle of which F G H
represents a portion.
In the construction of blades as first described in this specification, I make the
portion below the circle of greatest work incline away from the direction of rotation
and the portion above the circle in the direction of rotation. The section of a blade
so constructed will be more or less similar to Fig. 2, where similar letters denote the
corresponding parts of Fig. 1. The bending, inclination or curvature of each part will
of course he varied according to the work required to be done.
The blades are so placed & formed that their surfaces are at an angle to the plane
of rotation and as before described the angle increases from the boss in the case of the
lower part of the blade and from the periphery in the case of the upper part of the
blades, until each meets the circle of greatest work at which point they attain their
greatest (but not necessarily exactly similar) angle as regards the plane of rotation.
A blade in back view would then appear similar to Fig. 3. in which Z Y X represents
the leading edge and Z¹ Y₁ X' the trailing edge of the blade. The leading edge of
the blades of any of the apparatus, arrangements or combinations described in this
specification may have fastened to, or forming part of it, a piece of sheet metal or
the like, with a flat, curved or twisted or partly flat, curved or twisted surface and
having a form somewhat like Z Y X (Fig. 3) on the back or trailing edge and like
the dotted line from Z to X on the front or leading edge: this additional piece may

page_text: if desired be at an angle to the plane of rotation & be of such a form as will produce a
propelling effect as well as, & in addition to the blade proper.
As before mentioned the two parts of the blade need not meet abruptly on the
circle F G H, but may be run into each other with a curve as shewn by or similar to
the dotted portions of circles in Figs. 2 & 3. Fig. 4 shews the plan of the blade
shewn in Fig. 3. W. represents the axis of rotation & the arrow the direction of
rotation for propelling the air in the direction of arrow U.
Y. Y shews the
approximate angle the blade makes with the plane of rotation on or about the circle of
greatest work. The dotted line ZTY shows about the position which the sheet of
metal above referred to would occupy when fastened to the leading edge of a blade
of this form, when it (the plate) is at an angle to the axis of rotation for the purpose
already mentioned.
The lower part of the blades may be prolonged above the circle of greatest work &
the upper part may be continued below that circle & in some cases a space may be left
between each part of the blades on the circle of greatest work, in which case provision
must be made by rods, bars, rings, or the like for supporting each part of the blade at
its proper distance from the axis of rotation.
The root of the blade shewn in the drawings is shown as tangential to the boss ;
is obvious that they may be made and fastened more or less radially thereto.
it
The bends, curves, inclinations, proportions details & other inatters may be
considerably varied from what is described in the specification or partly shewn in the
drawings without departing from the principles of my invention.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same may be performed I declare that what I claim is
(1) The use and manufacture of improved apparatus for the purposes of this
Invention as set forth in the title and specification, the said apparatus having blades
each of which is so formed that one part pushes up the air (or other medium acted
upon) from the centre of rotation towards the circle of greatest work herein before
mentioned and the other part pushes the air or other medium, down from the periphery
of the apparatus towards the circle of greatest work. Such blades having their
leading and trailing edges perpendicular to, or forming an angle with, the longitudinal
projection of the axis of rotation, and their surfaces being at a constant angle or at an
angle varying at a constant or changing rate (either axially or radially, or both) to
the plane of rotation. The whole substantially as and for the purposes herein before
mentioned and partly shewn in the drawings or any more modification or imitation
thereof.
(2) For the purposes of this invention and as a modified method of carrying it out,
the combination and use of two or more sets of blades, one or more set or sets being
inclined, curved, or bent away from the direction of rotation, and one or more of the
remaining sets being inclined, curved or bent towards the direction of rotation, the
said sets of blades being behind or in front of one another and revolving in one
direction and so formed as to have a propelling effect axially. The inclination &c. of
each set of blades extending from the boss to the periphery & the sets being sometimes
of different diameters to one another. The whole substantially as and for the purpose
herein before mentioned and described or any mere modification or imitation thereof.
(3) In connection with the combination described in Claim 2, the use & application
of the methods of preventing the radial escape of the air by wholly or partly
surrounding the set or sets of blades which are curved, inclined or bent away from
the direction of rotation, by a ring, cone, cylinder or the like or by turning over the
tips of those blades or fastening to them pieces of metal or the like to answer the
same purpose as turning them over, or by covering the tips of those blades by a
suitable piece of sheet metal or the like attached to or forming part of the other set
or sets the inclination, curvature or bending of which is towards the direction of
rotation substantially as herein before described or any nere modification or imitation
thereof.
(4) In connection with any of the apparatus constructed in accordance with the

page_text: principles of my invention the use and application of a wholly or partly inclined,
twisted, curved or flat plate or sheet of metal or the like, attached to the leading
edges of the blades of said apparatus, substantially as hereinbefore described with
reference to two forms of my apparatus and partly shewn with reference to one form
of apparatus in Figs. 3 and 4 of the accompanying drawings or any mere modification
or imitation thereof.
(5) The use and arrangement of two or more apparatus, fans or propellers or parts
of apparatus, fans or propellers revolving behind or in front of one another in opposite
directions, substantially as and for the purpose hereinbefore set forth or any mere
modification or imitation thereof.
(6) The combination and use of two or more apparatus, fans or propellers or parts
of apparatus, fans or propellers behind or in front of one another, having different
diameters & when necessary different pitches and each revolving in the same or
different directions, substantially as and for the purpose hereinbefore set forth and any
mere modification or imitation thereof.
(7) In the construction of either a single apparatus or of any of the arrangements
or combinations referred to & mentioned in this specification the use of only certain
parts of the blades above and below the circle of greatest work, supported, or sliding
on rods, bars, rings or the like as and for the purpose herein before described and any
mere modification or imitation thereof.
(8) The use and application of a revolving or stationary ring, cone, cylinder or the
like, wholly or partly surrounding any or all of the apparatus, arrangements or
combinations substantially as hereinbefore mentioned or any mere modification or
imitation thereof.
(9) The general arrangement, construction and combination of the several and
respective parts (or any mere modification of them) together forming my improved
apparatus, arrangements or combinations substantially as hereinbefore described and
partly illustrated by the drawings.