This invention relates to small tilting tub-type concrete mixers and is a continuation in part of the co-pending abandoned application of Michael V. Gilson, Serial No. 515,355, filed December 23, 1943, and entitled Concrete mixer.
In mixers of this type the mixing drum is rotatably mounted on a yoke by means of a suitable bearing structure carried by the closed bottom of the drum and the adjacent central portion of the yoke. The drum is driven for rotation by a pinion meshing with a ring gear encircling the side wall of the drum, and the yoke is swingingly mounted to enable tilting the drum to and from its discharging position.
Inasmuch as mixers of this type are generally of small capacity for low cost and portability, simplicity of construction is a highly important factor.
It is, therefore, an object of this invention to provide a concrete mixer of the general type described which is so constructed and designed as to simplify its manufacture to thereby effect a considerable reduction in manufacturing costs.
In accomplishing this end, this invention contemplates the provision of a novel ring gear for the mixing drum which can be economically made from ordinary bar stock, whereas in the past, expensive cast and cut ring gears have been employed in the drive for the drum.
With a further view toward the reduction of manufacturing costs, it is another object of this invention to provide a novel two piece drum construction which enables the ring gear on the drum to be guarded in an extremely simple manner.
Still another object of this invention is to so associate the ring gear and its guard that the guard not only protects the gear from materials that may spill over the edge of the mixer drum but also carries part of the axial thrust imposed upon the ring gear by the drive pinion with which it meshes, thereby securing added strength in a simple and inexpensive manner.
With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination, and arrangement of parts substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.
The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which: Figure 1 is a front view of a concrete mixer embodying the features of this invention and having parts thereof broken away and shown in section to better illustrate the structure thereof; Figure 2 is a partial top view of the mixer shown in Figure 1; Figure 3 is a view illustrating a portion of a notched bar from which the ring gear of this invention is made; and Figure 4 is an enlarged detail sectional view through a portion of the drum wall showing the manner in which the guard for the ring gear also provides for attachment of the gear to the drum. Referring now more particularly to the accompanying drawings in which like numerals indicate like parts, the numeral 4 designates a supporting frame which, in the particular type of mixer shown, is customarily mounted on skids 5. The mixer drum 6 of this invention is rotatably carried by a yoke or cradle 7 having trunnions 8 at its opposite ends by which the yoke is tiltably supported on axially aligned bearings 9 on the upper portion of the supporting frame. The drum is of novel construction and comprises a relatively cup-shaped sheet metal bottom section 10 having its bottom wall II disposed adjacent to the yoke 7 with its open end facing upwardly away from the yoke, and a frusto-conical outer section 12 having its large diameter end portion fitting and telescoped into the open end of the bottom section and welded thereto as at 13.
The upper frusto-conical drum section 12 thus provides, in effect, a continuation of the side wall of the bottom section so that the side wall of the drum is formed jointly by the circumferential wall portions of the upper and lower drum sections with the open small diameter end 14 of the frusto-conical section 12 providing a discharge mouth for the mixing drum.
The center of the closed bottom wall II of the drum is provided with a hub 15 to receive a shaft 16 with the shaft projecting down axially of the drum beneath the bottom wall thereof to be stepped into a bearing .1 carried by the yoke or cradle 7. A collar 18 secured .on the end of the shaft at the underside of the yoke holds the shaft and consequently the drum against axial displacement and thus permits the yoke to be swung to tilt the mixing drum to its discharging position, a handle 19 being provided for this purpose.
Prior to assembly of the two drum sections the upper edge of the lower drum section is spun substantially radially outwardly to provide an annular flange or rim 20 projecting from the side wail of the drum. The flange or rim 20 is disposed substantially normal to the drum axis but has its outer edge portion bent downwardly as at 21 so that the underside of the flange is hollow giving it substantially a channel shaped cross section. This flange not only has the function of reinforcing the drum adjacent to the connection between the two drum sections, but also provides a guard for the ring gear 22 of this invention.
The ring gear is of novel construction and comprises a relatively flat ring shaped bar bent edgewise into circular shape from a piece of flat bar stock, indicated at 23 in Figure 3, in which equispaced tooth forming notches 24 are formed entirely along one side edge of the bar. After formation of the notches 24 in the bar, the same is bent edgewise so that its opposite ends abut, it being assumed that the length of the bar has been predetermined in accordance with the circumference of the mixer drum and so that all portions of the ring thus formed lie between two parallel planes defined by the opposite fiat sides of the bar.
The ring thus formed has its gear teeth disposed on its inner edge, and is applied to the side wall of the bottom drum section with the extremity of the gear teeth lying closely adjacent to the drum wall and with one flat side of the gear against the downturned outer edge 21 of the annular flange 20.
As indicated in Figure 4, the ring gear is secured to the drum by welding the extremities of the teeth directly to the drum wall as at 25, and by welding the downwardly bent outer edge portion 21 of the lip to the upper face of the ring gear at the unbroken outer periphery thereof as at 26. Thus, it will be noted that the ring gear augments the annular flange 20 in reinforcing the drum adjacent to the juncture between the two drum sections and that the flange acts as a guard for the ring gear teeth.
The drive for the drum is provided by a pinion 27 fixed to a drive shaft 28 passing through one of the trunnions 8 on the yoke so that the axis of the drive shaft extends at right angles to the axis of the drum. The toothed edge of the drive pinion thus lies in juxtaposition to the side wall of the mixing drum and between the ring gear 22 and the bottom of the lower drum section.
With this disposition of the drive pinion the teeth thereof lie closely adjacent to the drum wall and engage in the tooth forming notches 24 of the ring gear from underneath the gear to transmit rotation from the drive shaft 28 to the drum.
It is to be noted that by virtue of the relative disposition of the ring gear and the guard provided by the flange 20 part of the axial thrust imposed upon the ring gear is carried by the guard. Added strength is thus achieved in an extremely simple and inexpensive manner.
From the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in the art that this invention provides a small tilting concrete mixer which by reason of its novel construction features low manufacturing cost; and that the ring gear for the drum is exceptionally well guarded by the annular rim which reinforces the drum wall medially of the ends of the drum.
What I claim as my invention is: 1. In a concrete mixer of the type having: a mixing drum provided with a relatively cupshaped bottom section and a frusto-conical extension for the side wall of the bottom section defining the mouth of the drum, said frustoconical section being telescoped inside the bottom section and welded thereto: an annular lip curled outwardly from the upper edge of the bottom section adjacent to the juncture of said sections; a ring gear encircling the side wall of the bottom drum section adjacent to the underside of said annular lip to be protected by said lip, said ring gear having its teeth projecting substantially radially inwardly toward the side wall of the drum from an unbroken rim portion constituting the outer peripheral section of the gear; said teeth being secured to the side wall of the drum and a connection between the outer edge portion of the annular lip and said unbroken rim portion of the gear whereby the lip carries part of the thrust imposed on the gear by meshing engagement thereof with a drive pinion at the unguarded side of the gear.
2. In a concrete mixer of the type having a mixing drum provided with a circumferential side wall: an annular flange fixed on the side wall of the drum having a substantially channelshaped cross section with the open side of the channel facing in the direction of the closed end of the drum; a ring gear encircling the side wall of the drum adjacent to the open side of said channel-shaped flange with the teeth of the gear projecting substantially radially toward the side wall of the drum from an unbroken rim portion of the gear; means securing the teeth of the gear to said side wall of the drum; and means securing the portion of said flange remote from the drum wall to the unbroken rim portion of the gear whereby the gear is supported at radially spaced points from the drum and the flange acts as a guard covering one side of the gear and carries part of the thrust imposed on the gear by meshing engagement thereof with a drive pinion at the unguarded side of the gear.
3. In mixing apparatus of the type having a rotatable drum open at one end and closed at the other and having a circumferential side wall: an annular reinforcing flange encircling the drum and fixed on the side wall thereof intermediate its ends; a ring encircling the drum and fixed on the side wall thereof between the flange and the closed end of the drum, said ring and flange being in juxtaposition, and the ring having equispaced apertures along its inner portion to define a ring gear, the teeth of which are adapted for meshing engagement with the teeth of a drive pinion at the side of the ring facing the closed end of the drum; the flange acting as a guard covering the ring gear teeth to shield the same from materials charged into the open end of the drum for mixing; and means securing the periphery of the flange to the outer imperforate portion of the ring remote from the side wall of the drum so that the flange carries part of the axial thrust imposed on the ring by meshing engagement thereof with a drive pinion at the unguarded side of the ring.
1ICHAEL V. GILSON.
60 REFERENCES CITED The following references are of record in the file of this patent: UNITED STATES PATENTS Number 267,368 748,653 1,327,575 1,714,359 1,766,582 1,789,224 1,920,154 1,920,354 Name Date Preston----------- Nov. 14, 1882 Richter ----------- Jan. 5, 1904 Jaeger ------------Nov. 25, 1919 Gambon ----------May 21, 1929 Ball --------- June 24, 1930 Edlund ------------ Jan. 13, 1931 Carlson ----------- July 25, 1933 Carpenter --------- Aug. 1, 1933