Mixer for Concrete, Cement, and other Substances".
Year: 1898

page_text: Reprinted
as amended in accordance with the decision of the Comptroller General,
dated the 29th day of July 1901.
COMPLETĘ SPECIFICATION (AMENDED).
"Mixer for Concrete, Cement, and other Substances".
I, FRANK BUNKER GILBRETH of No. 85 Water Street, Boston, Massachusetts, United
States of America, Contractor, 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 has for its object to provide a novel and improved device for
automatically mixing the various components of concrete, cement, mortar and other
substances of like or equivalent nature where it is desired to effect a thorough
mixture between various elements or substances.
The principal aim I have had in mind in devising a mixer containing my invention
has been to provide a mixer of extreme simplicity and of little cost, and one which
could be erected or put into position with little difficulty and without any previous
elaborate preparation or construction.
The various features of my invention will be hereinafter set forth in connection
with a description of the best embodiment of my invention now known to me, it
being understood, however, at the outset, that my invention is not restricted to the
particular embodiment which I have herein selected for illustration.
In the drawing, Fig. 1, in perspective, shows a mixer embodying my invention;
and
Fig. 2, a horizontal section on the dotted line x-x, Fig. 1.
Referring to the drawing in the embodiment of my invention there shown, A is a
long chute or trough, preferably substantially open at one of its sides, for instance
the front side, and provided at its upper end with a suitable hopper a, and at its
lower end with a receiving box or receptacle, which I shall hereinafter designate as a
receiver a¹.
This chute may be conveniently and cheaply made of wood, but for convenience in
transportation and handling and for durability I have found sheet metal as furnishing
very satisfactory results.
Preferably the front side of the chute A at or near the upper end of the latter, that
is immediately below the hopper a is closed by a front plate a³ to prevent escape of
the sand, cement, etc., when first thrown into the mixer.
At the bottom or outlet of the hopper a is arranged a suitable grating or screen,
herein shown as composed of a plurality of pins b, preferably parallel and also
removable.
These pins are arranged in such a plane and in such proximity as to exclude from
passage through the mixer all stones or lumps of such size as would interfere with the
proper mixing of the various substances or with the efficiency of the completed
mixture when taken from the device.
The angle at which the mixer is most conveniently supported, and the plane in
which the rods b are located are preferably either or both such as to give to each rod
an inclination towards the back or open side of the hopper to thereby cause stones,

page_text: Jumps, etc., excluded from the mixer by the rods to gravitate ont from the hopper
and onto the floor where they will not interfere with the proper use of the mixer.
After the material deposited in the hopper passes therefrom through the sieve or
grate at b, b, it thereafter meets and is acted upon by a succession of deflecting or
mixing members, shown as and preferably in the form of pins c, c, staggered through-
out the length of the mixer so as thoroughly and completely to mix the various
substances, such as sand, cement, stones of the proper size, etc., deposited in the
hopper and permitted to escape therefrom.
These mixing members c, c, are herein shown as arranged in series of two, or it
may be any other desired number, each transversely of the chute, each series of
mixing members c being shown as depending across the interior of the chute from
cleats or supports c¹, c¹.
Preferably these pin-like mixing members will penetrate the bottom back of the
chute, and be provided at the outside of the bottom back with some suitable means
for retaining them in position, but which, when desired, will permit removal of the
pins to facilitate cleaning when necessary.
Adjacent to the sides, and in lateral alignment with the respective series of pins
may be used deflecting plates c*, one for each series, sloping downwardly and
outwardly inwardly from the side of the chute, from which they may derive
support in any suitable manner, as by bolts 5 passing through both plate and chute-
side, the plates being, at their lower extremities, at a distance from the nearest pin
in the series about equal to the distance between the pins of the series.
The plates in respectively adjacent series are on opposite sides of the chute,
and aid in directing the material toward the median line of the chute.
Pins may be substituted for these plates, situated where the inner edge of the
lower extremity of the plate is, but there is a tendency of the material to wedge in
such construction, for the reason that the space between pins so placed, and the side
of the chute, is only one-half the size of the space between pins.
For the best results these mixing members c, c, are arranged at an angle within
the chute A. I have found that about the right angle is given to the pins by
carrying the pins depending from one cleat through the perforations in the bottom
back which are directly behind beneath the next succeeding cleat of the series.
This angular arrangement of the mixing members tends constantly to deflect the
material dropping through the mixer towards or against the back or-bottom thereof,
which latter, for the best results, is made concaved or otherwise depressed along its
median or center line, so that the constant tendency of the material from the time
it is deposited in the hopper to the time it is delivered from the delivery end of
the chute is to concentrate or mix along the median or lowest line of the bottom
back of the chute.
This greatly facilitates the thorough mixture of the material and the incorporation
therewith of the proper quantity of water as will he described.
The bottom-of-the receiving chamber, at a', furnishes a suitable receptacle for the
mixture at such times as the removal of the mixture is interrupted. For instance
the bottom of the chamber is contracted, as at a³, to form an opening a*, which may
be conveniently closed by the workman's shovel, the end of which is inserted within
the opening and supported on the inner inclined face of one receiver wall enabling
the workman by lifting the handle to completely close the delivery end of the
inixer.
During such time as it is closed in this manner, for instauce while the workmen
are changing wheel-barrows, buckets, or whatever is used to carry away the mixture,
the receiver a¹ takes care of all the mixture that descends through the mixer.
In the vicinity of the upper end of the mixer I have arranged a suitable water
spraying or delivering device, herein shown as in the form of a transversely arranged
pipe & perforated along its underside so as to deliver water within the mixer at the
proper point, 2.e. downwardly as well as inwardly in order that when the dry
mixture of the various substances has been sufficiently effected further mixing of the

page_text: same by the mixing members, acts to incorporate therewith the proper quantity of
water.
It is desirable for the best results that the mixture be first made while the
substances are dry and when all the stones and sand have been coated with the
cement or other binder used, the water is introduced to complete the mixture and
put it in proper condition for use.
For this reason the water which is discharged from the pipe d meets the dry mixture
approximately at one-third the length of the mixing chute and after the dry
substances have been thoroughly mixed.
The inlet pipe d' which supplies the pipe d is shown as depressed in loop form at
one side of the mixer in order that the controlling point, where is located the con-
trolling valve ², may be brought down into position convenient for the workman
standing at the delivery end of the mixer.
Thus the workman with his skilled eye will detect any variation in the mixture as
it issues from the device, and if it is too dry, he can, by a simple movement of the
valve, add to the quantity of water mixed with the substances, or if the completed
mixture is too wet he can restrict the quantity of water delivered and thus at all times
maintain the mixture at the proper consistency.
For convenience, the valve d² is a well-known three-way valve or cock, whereby the
water may be admitted to the device d or completely cut off therefrom, or while cut
off therefrom may be opened to permit the water in the pipe d, and the branches of
the U leading thereto to drain off through the three-way valve, as is desirable in cold
weather to prevent freezing.
The mixer may be supported in desired inclined position by any suitable supporting
means, I having found it convenient to employ a bar, as e, carried through suitable
eyes or rings el on the front side of the mixer, the normal tendency of this supporting
means being to maintain the mixer in such an angular position as will best tend to
concentrate the mixing operation at the back bottom or one side of the chute, and
thereby prevent its scattering as it would if the chute were truly vertical.
In fact I have found that for the best results the mixer should be as nearly horizontal
as possible and have the material gravitate freely through it without any tendency to
clog, and I have found that means such as herein shown hold the mixer at about the
required angle.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is
1. A In a mixer for concrete and the like, eonsisting of an open front chute or
trough with partly closed reeeiving chambers or spaces at opposite ends thereof
constructed substantially us and for the purpose specified.
2. A-mixer-for-eonerete-and-the-like, consisting-of-n chute or trough provided-at
one-end-with-a-suitable hopper, a-chamber immediately below-the-hopper-to-prevent
seattering of the substanees-shovelled-into-the-hopper, and-a-receiving-chamber-et
the lower-or-delivery end of the box-for-the purpose specified.
3. A-mixer-for-concrete-and the like, consisting of a-chute-or-trough-through
which the material to-be-mixed-may gravitate, a-sieve or-sereen at the supply-end
of the said chute, and mixing-means arranged in-said chute below-said-screen-for-the
purpose specified.
2. In a 4. A mixer for concrete and the like, consisting of a chute or trough, and
having a plurality of mixing members distributed in the length thereof, and staggered
to cause thorough mixture of material gravitating through the said chute sub-
stantially as hereinbefore described.
5. A-mixer-for-concrete-and-the-like, consisting of a-chute-having--a-trough-like
bottom-to-concentrate-therein-the-material-to be mixed.
6. A mixer-for-concrete-and-the-like; consisting of a chute-with mixing members
introduced along the length of said chute and at-an-angle-with one side of the
ehute, whereby the material is deflected by-caid--members-towards-suid side-of
the-chute-for-the-parpose-specified.

page_text: 3. 7. In a mixer for concrete and the like, the combination with a chute having a
or trough-like-bottom; of deflecting members arranged in said chute and inclined
with reference to the said trough-like or bottom to co-operate with the latter in the
concentration-and mixing of the material, substantially as and for the purpose
hereinbefore described.
4. 8. In a mixer for concrete and the like, the combination with a chute and
mixing members distributed along the length thereof, of a receiving chamber at the
delivery end of the chute, said receiving chamber having converging walls, and a
delivery opening between the latter, substantially as hereinbefore described.
9. In a mixer for concrete-and the like, a-chute-provided at its lower end with a
receiving-chamber-having-a-delivery-opening of less area than the--eross-sectional
area of the chute-and-chamber-to-enable-the-workman to control the delivery from
the chute.
10. In a mixer for
conerete-and-the-like,-the-combination-with-a-mixing-chute, of
water-supplying means-arranged-to-deliver-water-to-the-material-being-mixed in the
ehute.
5. H. In a mixer for concrete and the like, the combination with a mixing chute
provided with mixing members, of the type set forth of a water supplying device
constructed and arranged to spray water upon the material, being-mixed. substantially
as hereinbefore described.
6. 12. In a mixer for concrete and the like, the combination with a chute through
which the material gravitates during the process of mixing, a water supplying device,
and mixing members arranged in said chute both above and below the water supply-
ing device, whereby both dry and wet mixing may take place simultaneously within
the same chute or trough constructed and operating substantially as hereinbefore
described.
13. A-mixer-for-concrete-and-the-like, consisting of a chute-through--which--the
material-to-be-mixed gravitates, mixing-members within-said chute, water delivering
means-arranged-at-one-side-the-said-chute, and-means-to-hold-the-latter-in normally
inclined-position, whereby the-water-delivered-from-the-said-water supplying-means
is-enused-to-meet-the-mixture-within-the-chute-at-a-level below that of-the-water
supplying-device.
14. A-mixer for-concrete-and-the--like,-consisting-of-a-chute, mixing--members
arranged therein,a water-supplying device-arranged adjacent the upper portion of the
said-chutes-and-a-conduit-for-supplying said-water supplying device, said conduit
being carried-first-to-a-point-in-the-vicinity-of-the-delivery-end of the chute, then
upwardly-to-said-supplying device,-and-a-controlling-valve-located-at--or--neur--the
lowest-point-in-said supplying-conduit.
7. 15 Apparatus of the class described comprising an elongated chute transfixed-by
and mixing member therein consisting of parallel pins arranged in a plurality of
transverse series, said pins being staggered respectively with relation to the pins in
adjacent series; and deflecting plates, extended extending downwardly into said
chute from, and at an angle to, the walls thereof, said plates being arranged
in-staggered-relation alternately on opposite sides of said chute, one for each of said
series, each plate having its lower-extremity free edge in horizontal alignment with
the-pins-of-its-corresponding-series and placed relatively to the nearest adjacent pin
at a space corresponding to that between said pins, constructed and operating sub-
stantially as hereinbefore described.
1000