US2439250A - Transit concrete mixer - Google Patents

Description

Ap 6, 1.948. 1 .G. HlLKl-:MEIER l TRANSIT CONCRETE MIXER Filed DeO. 27, 1943 Louis '/emjez'er` INVENTOR.

BY yf ATTORNEY.

FIG. 3

Patented Apr. 6, 1948 `UNITED STATES PATENT OFFICE TRANSIT CONCRETE MIXER Louis G. Hilkemeier, West Allis, Wis., assignor to Chain Belt Company, Milwaukee, Wis., a corporation of Wisconsin Application December 27, 1943, Serial No. 515,834

7 Claims. 1

This invention pertains to a concrete mixer such as is provided with a rotatable mixing drum and an axial opening at one end for receiving and/ or discharging materials. Where such mixers are provided with a non-rotatable charging hopper, some diliiculty has been encountered in sealing the space around the opening in the drum.

In transit concrete mixers the concrete carried in the mixer drum often occupies more than half of the drum volume particularly where the drum is used as an agitator to haul previously mixed concrete, and even Where the drum axis is inclined with 'a discharge opening at the higher end, it may nevertheless be important to seal the opening to prevent the concrete from escaping from the drum. Concrete being of a very abrasive nature quickly deteriorates materials which it cornes in Contact with, such as the wearing surface between rotating and non-rotating parts,`

and sealing means now in use have generally been unable to resist the action of the concrete for more than a short period of time.

It is an object of the present invention to provide an improved. sealing ring for disposition in structures such as those described above, one Which will more adequately seal the space between the moving parts and last longer in service than seals heretofore employed. A further object of the invention is to provide a sealing arrangement and a separate bearing journal arranged so that closer sealing contact is effected as Wear occurs in other parts of the journal.

Another object of the invention is to provide improved means for mounting and supporting the hopper relative to the drum so as to maintain concentricity between the abutting surfaces of the drum and the hopper.

Still another object is to provide a concrete mixer having a charging mechanism and feeding means so supported with respect to the mixer drum that these parts will better withstand the abrasive action of the ce Lcrete than mixers heretofore employed.

With the foregoing other objects in mind, the invention resides in the novel disposition. and combination of elements as hereinafter described and as shown in an embodiment thereof illus` trated in the accompanying drawings, in which: Figure l is a side elevation partly in section, il

(ci. 25e- 161) 2 i lustrating the assembly of the hopper on the rear portion of the mixing drum;

Figure 2 is an enlarged section of the seal illustrated in Figure 2;

Figure 3 is a perspective View of the seal packing prior to its assembly in the hopper-drum structure.

Figure 4 is a section taken on the line --i of Figure 1; and

Figure 5 is an end view of the shaft closur shown in Figure 4.

Although Figurev 1 of the drawings illustrates only the rear portion of the mixer drum, reference may be made to Ymy copending applicationV Sel'. No. Z2,933 led March 2, 1942, ellttletl` Concrete mixer water supply system, now Patent No. 2,360,344, for a more complete disclosure of the function and disposition of the mixing elements of the mixer drum of a transit concrete mixer. Itis sufficient here to point out that while the drum rotates about its axis, the charging hopper is restrained against rotation in order that it may be held in upright, material-receiving position. In one of its aspects, the present invention is directed. to prevent leakage through the Space between the rotating drum and the non-rotating hopper.

In the embodiment shown in the drawing, the drum I I carries a pilot shaft I2 extending through the charging opening I3 a sufcient distance to adequately support the hopper Id, the inner end of shaft I2 being securely retained in a pair ofend portion adapted to be welded to flanged por tions I9 on the drum blades 2B. The hanged or lip portion I9 of the drum blades form an obtuse anglewith the lifting or web portion of the blades and extend just sufliciently beyond the inner side of the web portion to provide space for a fillet weld I8 as clearly illustrated in Figure 1. The

spokes on the two hubs I5 are at right angles to each other so as to support the shaft in two planes. The shaft is thus securely supported from all sides by a pair of axially spaced, supporting members and its alignment with the drum axis and the machined surface on the drum opening I3 is insured. This construction enables the following assembly operations to be performed:A

While the drum is mounted on its fixture for welding, a supporting arbor which fits snugly within hubs I5 is mounted axially of the drum. Brackets I8 are then adjusted on the spokes until the bevelled` end portion fits snugly against the blade flange I9. The brackets are next welded to the blades and a Weld is also deposited between the spoke and the bracket as indicated at 2| to rigidly connect them together. As the drum cools following the various welding operations which are performed on the blades and' on its shell, there is apt to occur distortion so as to make the hubs slightly eccentric with respect to the true axis. Shaft I2, which replaces the supporting arbor, the latter used only while mounting' the hubs, is sufficiently smaller in diameter than theV hubs by means of a through-bolt 22' extending through one of the hubs and the shaft I2. Should it be necessary to remove shaft I2, the through bolt is removed and collars I6, which are now integral with the hubs will form aligned openings for a replacement shaft and insure that the latter will be axially disposed in the drum when it is inserted through hubs IS.

Hopper I4 carries an internal sleeve 23 extending for substantially the full length of the hopper through its rear wall and the hopper is supported thereby. This sleeve is mounted on spaced bushings 24 each of which is protected against the entrance of abrasive material from the outside by means of packing rings 25. Grease may be supplied to the space between the shaft and the sleeve through a grease fitting 23 which extends from the under side of the sleeve and through the back wall 2'I of the hopper adjacent thereto. Provision is made for taking up the packing at the inner end of the sleeve by a packing nut 28 threaded on the sleeve, said nut having a notched portion 29 which may be aligned with a locking bar 30 removably secured to the under side of the hopper sleeve. The sleeve may be protected and the weight of the hopper distributed over the sleeve by any suitable connecting or covering meansrsuch as the plates shown in U. S. Patent 2,265,751 issued December 9, 1941 to Charles F. Ball.

The rear packing may also be taken up by adjustment of bolts 3! extending through a plate 33 enclosing the outer end of shaft I2. said screws being threaded into a pair of ears34 projecting from either side of a sleeve member 23, the latter serving as a housing for the packing gland 32 which encloses the shaft l2 with its inner end arranged to press against the rear packing ring 25. In this arrangement, which is best illustrated in Figure 4, plate 33 is provided with a centrally disposed opening 35 to vent air from the space between the end of shaft I2 and plate l33 during inward movement of the hopper on its supporting shaft. Sleeve member 32 is welded or otherwise made integrally secure to plate 33 and therefore when bolts 3| are tightened drawing plate 33 toward the hopper, sleeve 34 moves to the left as shown in Figure 1 causing the rear packing 25 to tightly seal the space between the shaft and its tubular housing. Shoulders 33 on the inner side of tubular member 23 limit movement cf bushings 24 toward each other, their movement away from each other being prevented by packing retaining means 28 and 33 respectively as previously described. Lubricant may be supplied to the space between packing rings through suitable means such as grease fitting 23,

As illustrated in the drawings, the hopper is somewhat elbow-shaped' and terminates in a lower portion which is substantially annular and somewhat smaller than the drum opening. This terminal portion of the hopper is spaced a distance axially outside the end of the drum and carries on it the sealing mechanism illustrated in more detail in Figure 2. Mechanism for sliding space is provided between the drum opening and the sealing mechanism for discharge of the mixed concrete from the drum, whereas, when the hopper is forced toward the drum, the sealing mechanism engages the end of the drum and rotates with it in closed, sealed engagement.

The sealing mechanism comprises a dished or frusto-conical closure ring 4i] having a flanged portion 4 Il abutting at substantially right angles a Wear ring 42 surrounding the drum opening. Since there is some relative movement between these two abutting surfaces, caused by the fact that closure ringv 4i) when brought into engagement with the drum may not be engaged sufficiently to cause rotation, a replaceable wear ring 42 may be skip welded or otherwise removably secured to the flange of the closure ring in position to engage the end of the drum. This ring may well be constructed in two semi-circular parts so that either may be replaced independently of the other for ease in assembly and also in the event wear should be localized on one of the parts.

The inner periphery of the dished closure member 4i! carries a channel 43 opening toward the charging passageway, said channel comprising two members 44 of Z-shaped cross section, with abutting surfaces 45 secured by a plurality of bolts 4S to the closure ring. Bolts 46 which are angularly spaced also support a bearing ring 41 spaced axially outwardly from the channel just described. As illustrated herein bearing member 4'I is an integral annular` casting having sleeve portions enclosing bolts 45, the sleeve portions being spaced angularly about the drumV axis as hubs in the manner and for the purposes set forth in Patent No. 2,281,820 to Charles F. Ball. As explained in said patent, should any grout work through the seal, it will esceape to the ground and not enter the bearing members.

Bearing portion 41 has an inner annular face and an outer, radial face for engagement with an annular member 48 of L-shaped cross section surrounding and secured to the lower portion of the hopper. The inner` annular bearing surj face is provided with two annular grooves 49 for reception of grease, the bottom of these grooves communicating with a recess in the outer radial bearing face for the transmission of the lubricant.` The radially hanged portion or` L shaped member 4l is secured to a skirt plate 5U, the latter being mounted on the hopper and secured thereto as' by the weld 5l. Plate Eil is recessed as at "52 for insertion of a grease litting 53 which extends 'through it and L-shap'ed member 48 in alignment with the groove in the outer radial face of bearing member 41.

Referring specifically to Figure 3j it will be seen that L-shaped member 4B carries on its outer annular face, packing elements arranged for retention in channel 43, which as previously described., is carried by the closure plate All. The packing element assembly comprises a ring member 54 which lits snugly around the rim or cylindrical portion of l.shaped member 43 and a pair of radially spaced bands 55 of normally hat but llexible material, the medial portion of the' inner band contacting and flexing about the convex outer surface 'of ring 54. The' two bands 55 are spaced slightly apart by a spacer ring 55,

which `may also be of flexible or yielding material, the bands,` spacer ring and supporting ring being retained in assembled relation by a plurality of radially spa-'ced rivets 5l extending through these elements and located in counterbored holes 53' in supporting ring et. These same counterb'ored holes 55 may loe employed to lock ring 54 against axial displacement or rotation with respect to its supporting member te, in which case tapped holes are arranged in menon ber 48 and cap screws can be inserted through appropriately disposed apertures in the walls of the hopper and threaded through member 43 till the ends of the screws extend into holes 5s to lock the supporting ring 54 in its desired position. l

The width of the retaining channel i3 which is associated with the closure ring 4l) is slightly less than the width of ilexible bands 55 and consequently when the bands are inserted in the channel they assume an arcuate form with their l end edges tightly pinched against the inner sides of the channel, the direction of flexing being such as to oppose and prevent the passage of material from the 'de 'of the hopper through the seal which is thus formed ybetween the packing bands and the channel.` As previn ously stated, when the hopper is moved into charging position, closure plate di! rotates with the drum due to frictional engagement, whereas bands 55 remain stationary since they 'are associated with the hopper which is held against rotation by the actuating arms 3l.

To further inhibit passage of concrete through the seal and to lubricate the rotating sealing sur faces, provision is made for packing the space between the outer of the sealing bands 55 and the web of channel 43 with a concrete setting inhibitor and lubricant. This is accomplished :by providing a grease tting 59 which communi cates through a hollow tube Sil with a specially constructed cap screw 6i havingprovision for receiving tube 60 and itself having a hollow portion for transmitting grease into opening 58. In this instance the rivet 5l which retains the packing assembly is hollow so that the grease may be forced back of the seal and will then work in opposition to material trying to pass the seal. One or more such grease ttings and hollow riv ets may be employed, it being understood that the remaining rivets are solid so that the only 6 place the grease may passout ofthe channel is through the space between the edges of the bands and the inner walls of the channel. Caip screw Si may also function as a retaining device for ring 54 with its head end accessi-ble` from the inside of the hopper the same as the' other rei taining cap screws.

Since the happier is under pressure to maine tain sealing engagement with the drum, movement of the hopper toward the left as shown in Figure 1 will cause sealing bands 55 to iloe pressed into closer contact with the inner flange of the channel c3, thereby making more eiective the seal which is relied upon to oppose the initial effort of the concrete tio escape. Furthermore as wear occurs between the radial face of the bearing member :il and the L-shaped supporte `ing ring, the `hopper will move also toward the left, thereby improving the seal and conxpensat ing in elect for suchlwear as may take place on the edges of the sea-ling bands.

While I have disclosedvpacking memberse as separate bands spacedby` a separate* member 55, they may well be moldedas one piece. Similarly instead of two such bands being employed, one band or even more than two bands might be substituted without departing from the spirit of the invention. I have found that belts made of canvas cut at a bias provide an end grain which is highly satisfactory due to the fact that the threads run diagonally across th'ebelt and thereby provide greater .resistance to wear at the edges which contact the inner sides of channel 43.

For supporting the drum il there is provided alim or track 53 spaced a short distance ahead of the charging and discharging opening I3 and surrounding the conical discharge portion of the drum. This rim or track is adapted to run on rollers mounted on the frame of the mixer which therefore provide a bed for the drum and support the rear `portion thereof. Reference may be made to aforesaid Ball Patent 2,265,751 for a showing of the disposition of said rollers with respect to the frame. Since the drum is mounted for rotation about an: inclined axis, the rollers exert axial as well as radial thrust on the track and dliiiculty has been experienced in providing a `track which can be so secured to the drum that it can withstand the strains inim parted in the regions where it is connected to the drum, said strains being especially severe when the mixer is transported over rough or irregular roads. I have found that by spacing track S3 a slight distance outwardly from the wall of the drum connecting only the medial portion of the track to the drum wall lby the use of a Supporting ring or web Se of sufficiently light section that Ythe web may flex or yield under variations in pressure on the track that these di'liculties can be` largely overcome and the welds provided they are suiciently limited in area so as not to build up the section when securing web et to the drum Il will stand up better under actualservice conditions. Furthermore, due to the less rigid construction employed, full contact is obtained between the track and the drum rollers.

"The supporting means for the drum constitutes thesubject matter of applicants copending application Serial Niunber 753,333, filed June 7, 1947.

From the foregoing it should be clear that there is provided an improved arrangement for supporting the mixing drum and the charging instrumentalities associated therewith whereby the charging element may be disposed concentrically with respect to an axial opening in the end of the drum. This is accomplished by a pilot shaft mounted on the true axis of the drum through the provision of hubs having a slightly larger aperture than the diameter of the shaft to compensate for eccentricity caused by manufacturing and assembly operation, said shafts coacting with a collar journalled on the shaft and secured to the hub after the shaft has been aligned with the true axis of the drum. In order to support the charging hopper adequately and resist the bending movement which it exerts on the pilot shaft, a pair of axially spaced hubs are provided with spokes rigidly secured thereto, which spokes comprise telescopic members which are adjustable prior to welding to locate the shaft axially of the drum. The outer ends of the spokes ,are rigidly secured to the blade flanges, said ends being bevelled in order that they may abut against the inclined outer surfaces of the blade flanges. Y i

Proper alignment between the charging hopper and the drum improves the sealing relation which is provided between their contacting surfaces and enables closure ring 46 to rotate with the drum and insures that bearing pressure will be transmitted through bearing member 41 which is disposed between the charging hopper and the rotatable closure ring. As previously described sealing bands 55 are pressed into sealing contact with the aforesaid closure ring, the closure ring being supported through bearing 4'! independently of the sealing bands, whereby the sealing members are maintained in floating relation and protect the bearing against abrasive action which would result if concrete could come in contact therewith.

, The invention having been described what is claimed is:

1. In a concrete mixer having a rotatable mixing drum provided with an axial opening at one end and a non-rotatable charging hopper varranged to feed material through said opening,

a Vrotary seal disposed between the hopper and the drum comprising a flexible band medially supported so that its edges may flex and a retaining channel rotatable with respect to saidV band, the web of said channel being concentric with said band and said channel being of width less than the width lof said band whereby the edges of the band are flexed into arcuate shape while retained by the flanges of the channel, the tendency of the band to straighten while so exed causing pressure to be exerted against the channel by said edges and opposing the passage of material through the seal.

2. A seal for concreteor like material between two concentric members one lof which is rotatable with respect to the other, comprising a ring secured to one of said members, a flat band of flexible material substantially wider than said ring having its medial portion secured to said ring, and an annular channel rotatable with the other member and arranged to Vretain the aforesaid band, with its web portion concentric with said band, the width of said band being greater than the width of said channel, whereby the edges or the band are flexed into arcuate form when pressed into the channel and each edge of the band forms sealing contact with the inner side of the flanges of the channel so that the material must pass seriatum through the sealing surfaces before it can escape through the seal.

3. In a concrete mixer having a charging chute held in non-rotating position and a rotating mixer drum with an opening at one end for receiving materials fed through said chute, a seal disposed between said chute and said drumcomprising a ring associated with the chute, a normally at band of flexible material mounted on said ring, an annular spacer element disposed between the medial portion of said bandY and the outer surface of said ring, a retaining channel rotatable with said drum havingits open end facing said ring and the inner sides of its anges contacted by the edges of said band and a hollow tubular member extending through said ring and said band for transmitting lubricant into the space between the band and the web of said channel.

4. In a concrete mixer, a rotatable mixing drum having an axial opening at one end and a charging device cooperating with said opening, a shaft axially disposed with respect to said drum and extending through said opening to slidably mount said charging device, a spiral blade mounted in the drum extending to said opening, said blade having a carrying lip formed at an obtuse angle to the blade, the surface of said lip being radially spaced from the axis of the drum, a hub supporting said shaft, a spoke oomprising two parts telescopically arranged with one end bevelled to abut against said lip and the other end locating said hub axially with respect to the drum, and means securing said telescopic parts against telescopic movement after location of said hub as aforesaid.

5. A seal as set forth in claim 2 comprising a plurality of such bands arranged concentrically and radially spaced from each other.

6. In a concrete mixer having a rotatable mixing drum and an axial opening at one end thereof, a shaft disposed axially of said drum and adapted to support instrumentalities concentrically associated with said opening, a fabricated assembly for supporting said shaft and permitting its accurate alignment with the drum axis comprising a hub having an opening larger than said shaft and through which the shaft may be extended, supporting means connected to the drum including at least one spoke made up of telescopic members, means securing the telescopic members in predetermined position, and a collar having an aperture suflicient to `ust contain said shaft, said collar being secured to said hub and locating the shaft on the true axis of the drum.

7. A seal between two members one of which is rotatable with respect to the other, comprising an annular member, a ring mounted on said member, a flat band of flexible material substantially wider than said ring having its medial portion secured to said ring, and an annular channel rotatable with the other member and disposed to retain the aforesaid band, the edges of the channel flanges being in close contacting position with respect to said annular member, and the web of said channel being concentric with said band,

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 529,831 Peckham Nov. 27, 1894 549,419 Wright` Nev. 5, 1895 937,359 Clark Oct. 19, 1909 944,423 Felix Dec. 28, 1909 1,246,089 Greenoe Nov. 13, 1917 Number Number Name Date Wege Mar. 26, 1918 Stromier Feb. 14, 1928 Nathan Mar. 3, 1936 `Funke Feb. 28, 1939 Ball Dec. 9, 1941 Ball May 5, 1942 Shafer June 9, 1942 Visser Apr. 6, 1943 Viall et al Sept. 7, 1943 FOREIGN PATENTS Country Date Holland Oct. 18, 1913 Sweden Sept. 30, 1941 Germany Apr. 10, 1930 France May 16, 1938

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