US2060090A - Concrete mixer - Google Patents

Description

Nov. 10, 1936.

E. E. LONG 2,060,090

CONCRETE MIXER Fi1ed Aug. 11, 1953 2 sheets-sheet 1 mlmlmn' llllmm llmllm 3nventor.

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Nov. 10, 1936. E E LCN@ 2,060,090

CONCRETE MIXER Filed Aug. ll, 1955 2 sheets-smet 2 lnventor,

Patented Nov. 10, 1936 UNITED STATES rATENr OFFICE Application August 11,

5 Claims.

This invention relates to continuous batch concrete mixers and has for its general object to produce a two compartment mixer of such nature that when the mixed concrete is being discharged 5 from one compartment, the other compartment may be charged with a predetermined quantity of aggregates, cement and water.

A further object of the invention is to provide a new type of transfer chute whereby the aggregates may be transferred from the receiving to the discharging chamber by means of a non-rotatable longitudinally slidable rod extending into or through both chambers of the mixer.

Another object of the invention is to produce a two compartment mixer of the revoluble tilting type, so arranged that the weight of the mix may be used to move the mixer to discharging position, and the weight of the aggregates to return the mixer to mixing position.

2O A still further object of the invention is to produce a cable drive mechanism which is particularly iitted for the driving of revolving drum mixers.

With the general objects named in View and others as will hereinafter appear, the invention consists in certain new and useful features of construction and organization of parts as hereinafter described and claimed; and in order that it may be fully understood, reference is to be had to the accompanying drawings, in which:-

Figure 1 is a side elevation of a mixer embodying the invention with parts of the stationary and movable cradles omitted and with the mixing drum broken away to illustrate the interior mechanism.

Figure 2 is a face view of an abutment for effecting the operation or the interior mechanism of the mixer.

Figure 3 is a view similar to Figure 1, but illustrating the mixer in the position of simultaneous charging at one end and discharging at the other.

Figure 4 is a section through the rod controlling the interior mechanism.

'Figure 5 is an enlarged view of the fluid cylinder brake mechanism for control of the speed of the tilting movement of the mixing drum.

Figure 6 is an enlarged view of the other end of the mixer from that shown in Figure to illustrate one form of drive cable take off.

Figures 7 and 8 are respectively side elevations and top plan View of a cable drive mechanism.

In the said drawings, where like reference characters identify corresponding parts in all of the figures, I indicates a stationary cradle which may 1933, Serial No. 684,664

be mounted on any suitable stationary or portable base, said cradle at its upper end being formed with bearings 2 for rotatably receiving trunnions 3 carried by a tiltable or movable cradle d. The cradle d is provided with proper weight support 5 rollers 5 and with abutment rollers 6, on which and between which, respectively, is mounted a rotatable tilting mixer drum, preferably, comprising a cylindrical portion l and a pair of identical end portions 8 and El, respectively, forming the 10 charging or receiving compartment or chamber for the aggregates7 cement, water, etc., and the discharging compartment or chamber for the mix or batch. The compartments are separated by a centrally located partition or dividing disc I0 of sufficient strength to carry the entire load of the mix, if necessary, as will hereinafter appear.

The mixer drum is adapted for continuous rotation as common in the art by any suitable drive mechanism, but in the particular machine illustrated is shown'as being driven or rotated by an endless cable drive II.

Arranged in axial alinement with the center of rotation of the mixer, the receiving chamber is provided with a ared charge receiving mouth l2, the partition or dividing disc has an opening I3, and the discharging chamber is provided with a discharging spout I4, the arrangement being such that when the machine tilts todumping position, as shown in Figure 3, the flared mouth I2 strikes a roller I5 journaled on the end of a rod I6 operatively connected to a gate II controlling the discharge spout of a storage or supply hopper I for aggregates, cement, water and the like (the water, however, customarily being fed from a separate tank). Thevcontents of the hopper thus will ow into the receiving chamber at the same time the previously mixed batch is ilowing out of the discharge spout.

Secured in any suitable manner .on opposite sides of the partition are a pair of spiders I9, provided with suitable openings in which are `iournaled bearing members 20, in which is slidably, but preferably non-rotatably, fitted, a rod or shaft 2| (illustrated as square in cross section, although this is not essential), extending out through the discharge spout I4, said rod being provided with an auxiliary spider support 22 within the discharging chamber and near the exit spout.

Permanently secured to the rod within the charging chamber is a gate, door o-r closure 23 oi suflicient diameter to close the opening I3 in the partition I0, and in iront of said gate and integral therewith if desired, is a discharge chute 55 24. The chute must have means to hold it in predetermined operating position at certain times and to this end in this embodiment of the invention, it is non-rotatably mounted on the rod 2|. The parts are so proportioned that when the machine is in mixing position the receiving end of the chute 24 is within the receiving chamber 8, while its opposite end extends downwardly into the discharging chamber 9. Inserted between the back of the gate or door, or of the chute if it also forms the gate or door, and the adjacent spider I9 is an expansion spring 25 which tends to thrust the door or closure to closed position, but as the structure, as here illustrated, is designed ior automatic operation, this closing thrust of the spring is resisted by contact of an L shaped foot 26 on the end of the rod 2| with a fixed abutment 21 carried by a pair of arms 28 secured to one leg of the fixed cradle, it being understood, however, that the spring 25 is not essential to proper operation, als gravity and the weight of the charge iiowing into the receiving chamber 8 may be utilized to completely close the gate as will hereinafter appear.

The two chambers of the mixer are each equipped with suitable flights 29 for working of the mix, and in addition to said flights, the receiving chamber is provided with a series of concrete elevating buckets 38, whereby the concrete in said receiving chamber, as it is being worked, is lifted by the buckets and discharged onto the end of the chute 24 and delivered to the discharging chamber 9 of the mixer.

The parts are so proportioned that when the mixer is empty, it will be in balance on its trunnions, with the axis of mixing rotation in substantial horizontal position. Assuming that the mixer, as shown in Figure 1, has an equal load on opposite sides of its trunnions and that the drum, as common with this type of equipment, is in constant rotation (it being here understood, that by preference, the parts are so proportioned that the time required for perfect mix corresponds with the rate at which the buckets transfer the load from one chamber to the other, the mix being completed simultaneously with the completion of transfer), it will be evident that finally the entire load will have been transferred by the buckets and chute to the discharging chamber. This overbalancing of the load tends to swing the mixer to dumping position, and in order to control such movement, one of the trunnions of the movable cradle is provided with a brake mechanism, which, as here illustrated, comprises, a lever 3| xed to the trunnion. The other end of the lever is pivoted to the end of a piston rod 32, which leads into a fluid pressure cylinder 33, having its opposite end pivoted at 34 to a fixed part of the machine, as to a leg of the stationary cradle. The piston rod 32 is equipped with a double acting piston 35 within the cylinder 33 (see Figure 5), and communicating with the opposite ends of the cylinder is a by-pass pipe 36 having a slow-action adjustable valve 31, and a manual quick acting control valve 38, the cylinder and by-pass being lled with fluid on both sides of the piston 35.

As the load is transferred to the discharging chamber by the operation of the buckets 30, the drum tends to tilt, but this operation is resisted by the compression of the fluid on one side of the piston 35. It is apparent that these parts must be heavy to stand up in service. When the operator is ready to discharge the mixer, he throws valve 38 to open position and the weight of the mix acting against the uid brake control mechanism, immediately commences to force the fluid to the opposite side o-f the brake piston, and the mixer will commence to tilt in accordance with the speed of uid transfer as set by the adjustable slow acting valve 31. As the machine tilts to discharging position, the gate rod foot 26 passes out of contact with the abutment 21 and the spring 25 or gravity, starts to close the gate 23, the parts being so arranged that by the time the receiving mouth l2 has opened the gate i1 controlling the charging hopper I8, the mixer gate 23 is closed or partially closed. In any event, if the gate is open, the weight of the load discharged from the hopper I8 will force it shut.

As the weight is now on the opposite side of the trunnions, the valve 38 having been previously closed, said valve is again opened to permit reverse flow of fluid with the consequent return of the mixer to mixing or horizontal position, it being understood that the drum is being continuously rotated through the movement described, the mixer gate 23 being opened through contact of the foot 26 of rod 2| with the fixed abutment 21.

It has been found that in the automatic operation of the machine as described, when the rod 2| has moved out of Contact with the abutment, friction of the parts will cause the rod, gate and chute to rotate with tlV mixing drum. The consequent result of such rotation is that it becomes possible for the chute 24 to be in improper position upon the return of the mixer to horizontal position. To guard against this, it has been found desirable for automatic operation, to make the abutment 21 in two sections: the upper portion being in the shape of a U, and the lower portion in the shape of an L, in cross section and facing the discharge spout of the machine. It is also essential that the flange of the L, which is at right angles to the axis of mixing rotation, shall be to the right or left of the machine in accordance with its direction of rotation. Now as the L foot 26 on the rod 2| contacts with the L portion of the abutment 21, and while it is being rotated by the mixer, the L foot on the rod will continue to rotate until it strikes the adjacent flange of the abutment, at which time it will point vertically upward. The position of the chute 24 on the rod 2| is in accordance with the position of the foot 26. The rod can no longer rotate, so it slides vertically upward with the chute in proper position and enters between the legs of the U portion of the abutment, where it is reliably held against accidental rotation in either direction by the rotation of the drum, or by the pouring of a load off its center line by the buckets 30.

As a convenient means of driving the drum, the endless cable Il, passes out through a hollow trunnion 4Q on the opposite side of the machine from the brake control, and said trunnion is provided with a pair of guide sheaves 4| in contact with the cable. The cable may then encircle the following driving mechanism: 42 is a driving shaft from any suitable source of power. Said shaft is equipped with a driving pinion 43 enmeshed with a pair of identical gear wheels 44, keyed or otherwise secured to shafts 45 and 46. The shaft 45 carries a pair of identical side by side drive sheaves 41, and the shaft 45 is equipped with a single drive sheave 48 arranged with its transverse center line in the center line between sheaves 41, and being of similar diameter to that of said sheaves. The drive cable Il leads from the mixer around one of the sheaves 41, thence around the sheave 48 and then back around the other sheave 41 from whence it returns to the mixer. With this construction, it will be apparent that all of the cable sheaves 41 and 48 are driven, and that all will apply power to drive the cable I l for the rotation of the mixing drum.

From the above description, it will be apparent that while I have described the preferred construction, it is to be understood that I reserve the right to all changes within the spirit of the invention and without the ambit of the prior art.

I claim:-

l. In a concrete mixer, a tiltable rotatable drum provided with a partition dividing same into a receiving and a discharging chamber, a door controlling communication between said chambers, and means controlled through tilting movements of the drum, arranged to hold the door open and non-rotatable during a mixing operation and to permit said door to close and rotate with the drum during a charging operation.

2. In a concrete mixer, a tiltable rotatable drum provided with a partition dividing same into a receiving and a discharging chamber and having an axial opening, a longitudinally slidable rod extending through said opening, concrete lifting appliances in the receiving chamber, a discharge chute and opening closure carried by said rod and moved thereby, and means for effecting movement of the rod to open the closure and place the discharge chute in operative position and to hold same against rotation when the mixer is in mixing position and to permit closure of the opening and rotation of the closure and discharge chute when the mixer is moved to tilted position.

3. In a concrete mixer, a tiltable rotatable drum provided with a partition dividing same into a receiving and a discharging chamber, the partition having an opening and said receiving and discharging chambers being respectively provided with openings in their opposite end walls, means for transferring the material from the receiving to the discharging chamber, a spring operated door to close the partition opening, and an abutment to hold the door open when the drum is in horizontal mixing position; movement to tilted position for simultaneous charge and discharge permitting operation of the door to closed position.

4. In a concrete mixer, a tiltable rotatable drum provided with a partition dividing it into a receiving and a discharging chamber and adapted to be tilted by the gravitative force of a preponderating weight on either side of the partition, a door in the partition controlling communication between the chambers, said door rotating with the drum during the charging and discharging operations, and means to hold the door against rotation during the mixing operation.

5. In a concrete mixer, a rotatable drum, a tiltable cradle rotatably supporting said drum, a pair of trunnions supporting the cradle, one of said trunnions being formed with a longitudinal passageway, and an endless cable drive passing through the hollow trunnion and encircling said drum.

EDWARD E. LONG.

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