US2276125A - Loading device for concrete mixers - Google Patents

Description

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LOADING DEVICE FOR CONCRETE MIXERS Filed Jan. 29, 1940 5 Sheets-Sheet 5 5 45/ i I :11: H 1% I 1 l Patented Mar. 10, 1942 UNITED STATES PATENT orricei LOADING DEVICE FOR CONCRETE MIXERS Application January 29, 1940, Serial No. 316,095

8 Claims.

This invention relates to a concrete mixer having a rotatable drum and a pivoted loading device or skip adapted, when lowered to receive material and when in elevated position, to discharge the material into the drum. It has been common practice to raise and lower the skip by a cable and pulley arrangement and when raised to vibrate it by mechanical means, such as a cam driven by the source of power rotating the drum, the cam co-acting with elements carried by the skip to give it a shaking or vibrating motion which loosens sticky material adhering to its sides and bottom and thus provides a clean discharge. In so mounting the skip that it may be vibrated, it may be pivoted on a horizontal bar which, through suitable supporting linkage carried on the mixer frame, is free to move under vibratory action. An illustration of a mixer and loading device of this type is shown in U. S.

Patent 1,742,420 issued January 7, 1930, to Samuel Shafer, Jr., in which vibrations of the skip are occasioned by camming lugs mounted on the charging end of the mixing drum in order to vibrate the supports in which the pivot rod of the skip is journalled and which are, in turn, pendently hung from the mixer frame. Because vibrations are horizontally obtained, this arrangement gives very desirable shaking action.

Instead of a pulley-cable arrangement for hoisting the skip, it has been proposed to use hydraulic means for this purpose. In the latter construction, a hydraulic cylinder is pivoted on the mixer frame, and a piston working therein for raising and lowering the skip has its piston rod operatively connected to the bottom of the skip. Since the thrust of the piston rod in elevating the skip to discharge-position is away from the mixer, it is necessary that the raised skip be retained in proper proximity to the drum to enable the material to be discharged therein. This may be accomplished by attaching the dis charge throat of the skip or hopper to a horizontal shaft journalled in bearings that are fixed on the frame of the mixer in definite relation to the mixers charging opening. Shaking of a skip so mounted has been accomplished by swinging the skip on its pivoting rod, but this has resulted in complicating the hydraulic system because the piston rod is being forced to mov with the skip.

Vibrations are therefore transmitted through the hydraulic system to the mixer frame and the shaking which has been obtained has created undesirable strain in the machine.

It is an object of the present invention to provide a loading device for concrete mixers which will produce better shaking action than has heretofore been known. In accomplishing this object, it has become possible to elevate the loading device by hydraulic means, and when elevated to vibrate it by means independent of the hydraulic system used for raising the skip. In

this manner the advantages of hydraulic elevation may be obtained in combination with improved shaking action.

Other objects and advantageous features will be disclosed in the accompanying drawings and detailed description, wherein like numbers will be used to designate like parts, and in which drawings:

Figure 1 is a side elevation of a concrete mixer with a loading device shown in lowered or charge receiving position;

Figure 2 is a fragmentary side elevation with the loader in an elevated or drum-charging position;

Figure 3 is a front elevationof the loading device shown in Figure 2;

Figure 4 is sectional view taken on line 4-4 of Figure 2;

Figure 5 is a cross section taken on line 55 of Figure 2 showing the resilient mounting for the throat of the hopper; I

Figure 6 is an enlarged sectional view of the upper portion of the hydraulic cylinder, showing the relief valve mechanism;

- Figure 7 is an enlarged detailed perspective view showing the drum ring on which the camming lugs are mounted;

Figure 8 is a detailed side elevation of the arm and roller which actuates the skip vibrating mechanism.

Figure 9 is a sectional view taken on the line 9-9 of Figure 4.

The concrete mixer shown in the drawings has a drum l0 mounted on a frame I I, the drum being rotated by any suitable source of power such as the engine l2. One end of the drum is provided with a charging opening, and arranged to cooperate therewith is a loading device l3 having a throat portion l4 arranged to co-operate with the drum opening when the loading device is in elevated position.

The loading device l3 comprises a hopper l5 and a supporting frame Hi, the latter being disposed beneath the hopper and forming a cradle therefor. The frame [6 includes the side bars II, the ends of which adjacent the drum ID are pivotally mounted on a horizontal tube l8 journalled in bearings l9 mounted on mixer frame H. The rear or opposite ends of the side bars l1 form a housing for bearings journalling a shaft 2| to which are rigidly attached brackets 22 welded or otherwise secured to the bottom or underside of the hopper l5.

Supporting the throat or forward end of the hopper l5, and at either side thereof, are a pair of coil springs 23 seated on lugs 24 extending upwardly from the loader frame IS, the upper ends of the springs being seated against plate 25 extending laterally from the throat of the hopper. Brackets 28 mounted on the loader frame are provided with flanges 21 to limit upward thrust of the coil springs 23 and provides a bumper against which plate 25 may act.

For elevating the skip there is a hydraulic cylinder 30 encasing a piston 3| to which is'attached a connecting rod 32, the outer end of which carries a cross head pin 33 pivotally attached to the loader frame It. Cylinder 30 is pivotally supported on pins 34 mounted on the mixer frame I and when the skip is in lowered position, the cylinder may assume an approximately horizontal position with one end extending under the'mix ing drum.

Hydraulic fluid enters the cylinder 33 rearwardly of the piston 3| through a flexible hose or high pressure line 35 communicating with a pump 36 driven by the power plant |2 of the mixer. Fluid on the forward or low pressure side of the piston communicates through a flexible connection 31 with a reservoir 38, the latter communicating through a pipe 38 with the inlet side of the pump 36. A suitable by-passing valve 4| is inserted between the high pressure line 35 .and the return line 31. When valve 4| is opened and the fluid is lay-passed, the pressure against opposite sides of the piston is equalized and the skip may lower under its own weight.

To limit outward movement of the piston 3|, a relief valve 42 is provided in the piston, this valve being actuated by an adjustable setscrew 43 threaded in the outer end of the cylinder 30. Another adjustable setscrew 44, also threadedin the head of the cylinder 30, serves as a stop to limit outward movement of the piston. Consequently, when the skip reaches, the desired angle of elevation, valve 42 is opened, through contact with stop 43, and hydraulic pressure back of the piston forcing the skip upwardly is relieved, but sufficient pressure is maintained to hold the skip in elevated position while the load in the skip is discharged into the drum, after which the valve 4| is opened and the skip lowers under its own weight.

For shaking the skip, camming lugs 45 are provided on the face of the drum H] in accordance with Shafer Patent 1,742,420 previously mentioned. These lugs co-operate with a roller 46 carried by an arm 4'! mounted on the end of a shaft 48 journalled within tubular member l8. Rigidly secured to the underside of the throat portion M of the hopper H5 is a depending ear 49 connected through a link 50 to an arm 5| secured to the inner end of shaft 48. For adjusting the position of the roller 45, arm 41 is made in two parts lla-47b) with arcuate slots 52 in part 41b to permit relative displacement and adjustment of the parts when bolt assemblies 53 which connect them are loosened.

In operation the loaded skip is elevated by closing the valve 4| to build up hydraulic pressure in back of the piston 3|. When the desired elevation is obtained, upward movement is arrested by the automatic opening of valve 42. In this position skip I5 is pendently supported on its tilting frame I6 by shaft 2| and through lever system 4'|485|--5049, camming action between roller 46 and rotating cams 45 pulls hopper throat l4 downwardly against compression springs 23. As each cam passes the roller, springs 23 snap the hopper throat upwardly against arresting stops 21 and since there are a number of cams on the drum face (Figure 7 shows eight but more or less may be attached to the drum face as desired) a series of rapid hammer-like blows or vibrations are imparted to the skip at its throat portion without setting up undue or abnormal pressure strains in the structure itself. The impulses resulting are transmitted throughout the hopper, including the portion beyond the end of the frame, and promote a very efficient discharge of all material into the drum. Springs 23 normally keep the throat of the hopper away from the loader frame, except when compressed by the cam actuating mechanism.

While the invention has been illustrated in one particular form, it is recognized that various modifications maybe made in order to adapt it for use with vibrating mechanism other than the type shown in the aforesaid Shafer patent and described herein. The provision of an independent tilting frame for the hopper permits means to be utilized to suspend the hopper pendently adjacent its basal part so that it may be vibrated when in raised position. The method of suspension selected will depend upon the direction of movement imparted to the skip by the vibrating mechanism.

The pivotal suspension described herein is considered desirable when horizontal vibrations :are imparted to the-throat of the hopper, since the impulses created during pivoting of the pendent skip on the frame cause material to be thrown from the portion of the hopper which extends beyond the point at which the hopper is pivoted on the frame, as well as from the throat portion and the dry material, once loosened from the hopper, slides downwardly into the drum. In some in stances, however, it may be desirable to pendent- 1y hang the hopper upon the elevated frame by means of springs, and in other cases to so hang it that it may be oscillated vertically in the frame. Considering possible variations, the invention is not intended to be limited except in accordance with the following claims.

I claim:

1. In combination with a frame for a concrete mixer, a rotatable mixing drum-mounted thereon and power means for rotating the-same, a second frame member tiltably supported on the mixer frame, a loading hopper pendently hung on said second frame member when in elevated position, hydraulic means for elevating said second frame to position said hopper for discharge into said drum, and means for vibrating said hopper independently of said second frame member while said hopper is in load-discharging position.

2. A loading for concrete mixers comprising a frame, a loader carriage tiltably mounted at one end to said frame, a loading hopper pendently supported on said loader carriage when in elevated position, spring means for supporting the forward end of said hopper on said loader carriage, a stop mounted on said loader carriage for limiting movement of said hopper under pressure from said spring means, and means operatively connected to said hopper to overcome the pressure of said spring means and cause a periodic bumping of said hopper against said stop.

3. A loading device for concrete mixers comprising a tiltable frame and a charging hopper pivotally mounted thereon, said hopper having a throat portion resiliently mounted on said frame, and said frame carrying a bell crank one end of which may be oscillated by a source of power while the other end is linked to the throat of said hopper to transmit vibrations produced by the oscillations of said crank.

4. A loading device for concrete mixers comprising a tiltable frame and a charging hopper pivotally mounted on said frame intermediate the ends of said hopper, resilient means for supporting the throat portion of said hopper, a pivot bar at the end of the loader frame adjacent the concrete mixer and a bell crank journalled on said pivot bar, with one arm linked to the throat of said hopper and the other arm disposed to be oscillated by an actuating mechanism.

5. In combination with a rotatable drum for mixing concrete and a frame for supporting the same, a loading skip for charging said drum, a loader carriage mounted on said frame and resiliently supporting said skip, hydraulic means carried by said frame for elevating said carriage and maintaining it in elevated position, and means for vibrating said skip independently of said hydraulic means while said carriage is maintained in elevated position.

6. A loading device for concrete mixers comprising a pivotal frame and a charging hopper cradled therein, adapted to be elevated as a unit from load-receiving to load-discharging positions, said hopper when in load-discharging position being pendently supported on said frame at a point considerably removed from the lower or throat portion of the hopper, and means associated with the hopper for receiving impulses causing said hopper to strike said frame at a point intermediate the pivot point of the frame and the point of pendent mounting of the hopper. 7

7. A loading device for concrete mixers comprising a tiltable frame and a loading hopper pivotally mounted thereon, a spring supporting the discharge portion of said hopper on said frame at a point removed from the pivot point of the hopper, whereby said hopper and said frame may be tilted as a unit, a stop mounted on the frame for limiting spring action, and means associated with the hopper for receiving impulses which will overcome said spring and cause a pivoting of said hopper on said frame followed by a bumping of said hopper against said stop,

8. In combination with a rotatable drum for mixing concrete and power means for rotating the same, a frame for the mixer, a loader frame tiltably mounted on the mixer frame, a charging hopper cradled in the loader frame and arranged to be tilted therewith from load-receiving to drum-charging positions, said hopper when in the latter position being free to move with respect to the loader frame, means for tilting the loader frame, and means actuated by the power means for vibrating the hopper while the loader frame is stationary and the hopper is in drumcharging position.

GEORGE K. VIALL.

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