IMPROVEMENTS IN CONCRETE MIXER TRUCKS

Abstract: A concrete mixer truck in which the vehicle chassis is provided with a framework (2) which supports a rotary drum (3) in which, in use, a concrete mixture is prepared and transported. The drum (3) is provided with a discharge opening (5) and an underlying discharge duct (6) arranged to allow the transfer of the concrete mixture from the drum (3) to the place of use. The discharge duct (6) has an axial length which is continuously variable between predetermined minimum and maximum values. Manually operable control means (70, 17, 18), when operated, cause a variation in the axial length of the said duct (6). Further control means (71;42;53) are arranged to rotate the duct (6) about a vertical axis and about a horizontal axis.

Description: "Improvements in concrete mixer trucks The present invention relates tocomrete mixer trucks, that is to vehicles for conveying a concrete mixture in which the vehicle chassis is provided with a framework which supports a concrete mixer in the form of a rotary drum, in which the concrete mixture is prepared and transported; the said drum has a.discharge opening and an underlying discharge duct able t9 allow the transfer of the concrete mixture from the drum to the place of use. In concrete mixer trucks of conventional type the discharge duct has a fixed length. To this duct element there can optionally and releasably be connected a further extension duct element,also of fixed length. After the concrete mixer truck has reached the place of use of the concrete mixture prepared therein, the driver of the truck must normally carry out repeated manoeuvres to bring the truck closer to the structure into which the concrete mixture is to be-transferred. This structure may, for example, consist of a wooden or metal formwork. The manoeuvres necessary to bring the end of the discharge duct of the concrete mixer truck into the correct position relative to the formwork are usually complicated to carry out. Indeed, since the opening and the discharge duct of the concrete mixer truck are usually in the rear part of the vehicle,these manoeuvres for bringing the discharge duct closerto the formwork are carried out by driving the vehicle in reverse. Thus the driver cannot directly control The position of the discharge duct relative to the formwork and, consequently, this make-s it necessary for a second operator to intervene from the ground to provide the driver of the doncrete mixer truck with the necessary signals to carry out the manoeuvre correctly. This results in a considerable loss of time both for the driver of the truck and for the operator who assists him during these manoeuvres. A further problem inherent in the stage of transferring a concrete mixture from a concrete mixer truck to the structure intended to receive this mixture occurs when the concrete mixer truck must manoeuvre close to a slope. This situation occurs, for example, when the structure intended to receive the concrete mixture is at a height below the plane on which the truck manoeuvres. This situation arises for example,during the formation of the foundations of a building. In the situation described above, it is necessary to extend the discharge duct of the concrete mixer truck so as to enable the transfer of the concrete mixture from the mixer to the receiving structure located below the plane on which the truck moves. In this situation recourse is normally made to a plurality of duct elements provided with hook or fixing means at their ends to allow their interconnection, and their connection to the discharge duct of the mixer truck. In every case these extension elements are of fixed length. Therefore the entire length of the discharge duct formed by using these elements cannot be varied continuously but only through discrete values corresponding to the length of each extension element. Consequently in this situation the driver of the mixer truck must again manoeuvre the vehicle, in the manner described above, to bring the end of the extended discharge duct into the correct position relative to the structure which is to receive the concrete mixture. The object of the present invention is to provide a concrete mixer truck which allows the problems described above to resolved. In order to achieve the said object, the present invention provides a concrete mixer truck of the type specified above the main characteristic of which lies in the fact that the said discharge duct- has an--axial length which is continuously variable between predetermined minimum and maximum values, and in that first manually operable control means are provided which, when operated are able to cause a variation in the axial length of the said duct. Further characteristics and advantages of the concrete mixer truck according to the present invention will become apparent from the detailed description which follows, made with reference to the appended drawings, provided purely by way of non-limiting example, in which: Figure 1 is a side view of the rear part of a concrete mixer truck provided with a discharge duct according to the: :invention,in its extended configuration, Figure 2 is a side view of the concrete mixer truck of Figure 1, with the discharge duct in its retracted condition, Figure 3 is a perspective view of a discharge duct according to the invention, Figure 4 is a partial perspective view of a duct element forming part of the discharge duct of Figure 3, Figure 5 is a partial side view of the discharge duct of Figure 3, Figure 6 is a partial perspective view of a variant embodiment of control means for the discharge duct of Figure 3, and Figure 7 is a perspective view of the end portion of the discharge duct according to the invention, provided with a terminal curved element. With reference to Figures 1 and 2, a concrete mixer truck is indicated 1, the chassis of which is provided with a framework 2 which supports a concrete mixer 3 in the form of a drum rotatable about an inclined axis lying in the median longitudinal plane of the vehicle. The rear end of the concrete mixer 3 is provided with a loading hopper 4 and a lower discharge opening 5. A discharge duct, generally indicated 6, is supported by the framework 2 beneath the discharge opening 5 of the concrete mixer. As will be better EUescribed below, the discharge duct 6 can be extended and shortened contfnuously in the axial direction. Figure 1 shows the discharge duct 6 in its configuration of maximum length. Figure 2 illustrates the discharge duct 6 in its configuration of minimum length. As illustrated in Figures 1 to 3, a vertical plate 7 is fixed to the rear end of the framework 2 of the truck. A sleeve 8 is fixed to the vertical end edge of the plate 7. Within the sleeve 8 is rotatably mounted a shaft 9, to the upper end of which is fixed an arm 10. A first duct element ii is connected to the upper end of of the arm 10 so as to be rotatable about a horizontal axis X-X. Adjacent the arm 10, the facing side walls of the duct element 11 are connected by a lateral wall 11a. The end portion of the duct element 11 facing the arm 10 is always located below the discharge opening 5 of the concrete mixer 3. To the median portion of the duct element 11 close to the upper edges of the side walls of the said duct element first and second fork elements 13, k4- are connected, so as to be rotatable about a horizontal axis Y-Y parallel to the axis X-X. The fork'elements 13, 14 are connected together by a shaft 15 which extends in the direction of the axis Y-Y through facing apertures formed in the side walls of the duct element 11. By 17 and 18 are shown first and second double-acting hydraulic cylinders supported by the fork elements 14 and 13 respectively so as to be rotatable about respective axes Z1-Z1 Z2-Z2, which are parallel to each other and perpendicular to the axis Y-Y. The hydraulic cylinders 17, 18 have respective rods 19, 20. By 21 and 22 are shown respectively first and second pantograph support structures each constituted by a succession of articulated parallelograms of equal sizes disposed in respective vertical planes. The pantograph structures 21, 22 are similar and parallel to each other. The articulated parallelograms of the structures 21, 22 at the ends adjacent the truck 3 are connected, so as to be rotatable about a horizontal axis, to the ends of the two arms of a fork element -25 which surrounds the lower part of the duct element 11. The fork element 25 is connected to therod26 ofa single acting hydraulic cylinder 27. The end of the body of the hydraulic cylinder 27 opposite the fork 25 is connected to a radial lug 9a at the lower end of the shaft 9, so as to be rotatable about a horizontal axis parallel to the said axis X-X. The lug 9a of the shaft 9 is preferably shaped in the form of a fork. To each articulated joint of the pantograph structure 21 ,common to two adjacent articulated parallelograms of this structure, there is rotatably connected a first end of a respective C-shaped-bracket 30 the concavity of which faces upwardly and the other end of which is rotatably connected to the homologous articulated joint of the other support structure 22. One end of a respective duct element 31 is attached to each bracket 30 for example by welding. The other end of each duct element 31 rests on the upper surface of the adjacent duct element 31. The lower surface of each duct element 31, close to the end opposite the respective bracket 30, has a plurality of longitudinal projections 32 (Figures 3 and 4) for facilitating the relative sliding of the respective duct element and the adjacent duct element. The free ends of the rods 19, 20 of the cylinders 17, 18 are interconnected by a horizontal cross bar 34 which, at the same time, acts as the articulation pin between the first and the second articulated parallelograms of the pantograph structures 21, 22 and the corresponding bracket 30. By 35 is shown an end duct element which is rotatably connected to the end articulated jointsof the pantograph structures-21, 22. The duct element 35 has two parallel arms 36 extending towards the concrete mixer 3, the upper edge of each arm 36 bearing against a respective stop pin 37 carried by the pantograph structures 21 and 22 respectively,close to the articulated joint which is common to the two end articulated parallelograms. By 38 are shown first and second pins carried by the upper edge of the duct element 35 in that end portion opposite the concrete mixer. To the lower end of the shaft there is fixed a disc 40 lying in a substantially horizontal plane and provided with a ring of substantially equispaced holes 41. A handwheel 42, lying in a substantially horizontal plane, is connected to the disc 40 by spokes 43. A bracket 45,disposed in a substantially horizontal plane, is rigidly connected to the lower part of the plate 7. This bracket has a hole 46 for receiving a stop pin 47. The lower end of this pin is adapted to engage a hole 41 in the disc 40 connected to the lower part of the shaft 9 to lock this disc, the hand wheel 42 and the shaft 9 in a predetermined angular position. In use, during the stage of transporting the concrete mixture, the discharge duct 6 is maintained in the retracted condition, in a position rotated through 900 (about the vertical) relative to that illustrated in Figure 2. Under these conditions the discharge duct 6 has a minimum extent. When the place of use is reached, the concrete mixer truck is stopped close to the formwork or other structure intended to receive the concrete mixture contained in the concrete mixer 3. The driver leaves his driving position and orientates the discharge duct 6 by operating the handwheel 42. Close to the rear part of the concrete mixer truck there are located first and second manually controlled hydraulic pumps 70, 71 (Figures 1 and 2) arranged to actuate the cylinders 17, 18 and the cylinder 27 respectively. By actuating the pump 70, the operator can cause the rods 19, rio to extend out from the cylinders 17, 18. Consequently the pantograph structures 21, 22 extend, causing the duct elements 31 to slide relative to each other. The overall length of the discharge duct 6 increases continuously. The operator stops the actuation of the cylinders 17, 18 as soon as the duct 6 has reached the desired length. When necessary the operator can rotate the discharge duct 6 upwardly or downwardly about the axis X-X by actuating the hydraulic pump 71 connected to the cylinder 27. The actuation of this cylinder effects translational movement of the rod - 26 of this cylinder and consequently rotation of the dudt 6 about the said axis X-X, by means of the fork element 25. If necessary the operator can also change the angular position of the duct 6 relative to the longitudinal median axis of the concrete mixer truck. For this purpose it suffices for the operator to unlock the handwheel 42, by extracting the pin 47 from the hole 46 in the bracket 45. Once this operation has been effected, the operator can change the position of the duct 6 by rotating the handwheel 42. When the desired angular position is reached, the handwheel 42 can again be locked in position by the introduction of the pin 47 into the hole 46 of the bracket 45 and into the hole 41 of the disc 40 corresponding to the desired position. From what has been explained above,clearly the discharge duct according to the invention eliminates the problem of carrying out the manoeuvres for positioning and bringing the concrete mixer truck close to the formwork (or other structure) intended to receive the concrete in the concrete mixer. Moreover, only a single operator is needed to position the end of the discharge duct 6 correctly relative to the formwork. Once the concrete mixture has been transferred from the concrete-mixer to a receiving structure, the discharge duct 6 illustrated in Figure 3 may easily be cleaned. This cleaning operation may be carried out simply by means of a jet of water and is facilitated by the possibility of rotating each duct element 31 upwardly independently of the adjacent duct element,as illustrated in Figure 5. According to a partially varied embodiment, illustrated in Figure 6, the rotation of the discharge duct 6 about the vertical axis may be controlled by means of a worm 50 rotatably supported by two arms 51 fixed to two brackets 45 rigid with the vertical plate 7 described above. The worm 50 is provided at one end with a handwheel 53. To the lower end of the shaft 9 there is connected a helically toothed worm wheel 54 the peripheral teeth of which engage the qp Worm - 50. The coupling between the worm 50 and the worm wheel 54 is preferably of the irreversible type. Rotation of the wheel 53, through the-worm 50 and the worm wheel 54, effects rotation of the shaft 9 and hence of the discharge duct 6. If, as has been indicated above, the coupling between the worm 50 and the worm wheel 54 is of irreversible type, no further means are necessary for locking the discharge duct 6 in the desired angular position. As illustrated in Figure 7, the discharge duct 6 described above may be fitted with a further duct element 60 provided, at one end, with a pair of lugs 61 each of which is forired with a hole for engagement by a respective pin 38 carried by the end duct element 35. As illustrated in the said Figure 7, the duct element 60 is curved and may be used for the lateral discharge of the concrete mixture from the concrete mixer 3 towards a receiving structure. More particularly, the duct element 60 may be used for directing a jet of concrete mixture into a lateral receiving structure, with the concrete mixer truck moving along this receiving structure. The curved duct element 60 preferably has a second pair of lugs 62 also provided with respective holes,andat the opposite end from the lugs 61.Thanks-to this device,it is possible to use the same curved duct element for discharging the concrete mixture on one side of the vehicle or on the other side. The duct elements 31, 35 and 60 may conveniently be formed in plastics material (polymer) to allow improved sliding of the mixture, a lighter structure for the discharge duct and easier cleaning of the latter.

Claims: CLAIMS 1. Concrete mixer truck in which the vehicle chassis is provided with a framework (2) which supports a concrete mixer (3) in the form of a rotary drum, in which, in use, a concrete mixture is prepared and transported; the said concrete mixer (3) being provided with a discharge opening (5) and an underlying -discharge duct (6) arranged to allow the transfer of the concrete mixture from the concrete mixer (3) to the place of use, characterised in that the said discharge duct (6) has an axial length which is continuously variable between predetermined minimum and maximum values, and in that first manually operable- control means (17, 18, 70) are provided which, when actuated, are arranged to cause a variation in the axial length of the said discharge duct (6). 2. Concrete mixer truck according to Claim 1, characterised in that the said discharge duct (6) has a telescopic structure. 3. Concrete mixer truck according to Claim 1 or Claim 2, in which the discharge duct (6) is connected at one end to the vehicle, for rotation about a horizontal axis (X-X) ,characterised in that it includes second manually operable control means (27) arranged, when actuated, to change the inclination of the discharge duct (6) relative to the horizontal plane. 4. Concrete mixer truck according to Claim 3, in which the discharge duct (6) is connected to the vehicle for rotation about a vertical axis, characterised in that it also includes further control means (42, 53, 5Q, 54) arranged, when actuated, to -effect rotation of the said discharge duct (6) about the said vertical axis. 5. Concrete mixer truck according to any one of Claims 2 to 4, characterised in that the said discharge duct (6) includes at least one pantograph support structure (21, 22) connected to the said first control means (17, 18) and having a length which is variable due to the effect of actuating the said first control-means (17, 18), and a plurality ofduct shaped elements (31) supported by the said pantograph structure (21, 22); each duct element (31) being interposed between a respective pair of duct elements (31) adjacent thereto and slidable axially relative to the said pair of adjacent duct elements due to the effect of a variation in the length of the said pantograph support structure (21, 22). 6. Concrete mixer truck according to Claim 5, characterised in that it includes first and second pantograph support structures (21, 22) disposed parallel to and facing each other, each of which forms a succession of articulated parallelograms; each articulated parallelogram having at least one articulated joint in common with an adjacent articulated parallelogram; and a plurality of C-shape brackets (30) connected, with the concavity facing upwardly, between an articulated joint common to two adjacent parallelograms of the said first pantograph structure (21) and the homologous articulated joint of the said second pantograph structure (22); there being connected to each said bracket (30) a respective duct element (31) of the said plurality of duct elements (31). 7. Concrete mixer truck according to Claims 5 or 6 characterised in that the said duct elements are of polymeric material. 8. Concrete mixer truck according to any one of Claims 5 to 7, characterised in that the said first control means comprise a pump (70) and at least one fluid cylinder (17, 18) connected to the said pump (70) and, the cylinder body being supported by the said framework (2) and its rods(19,20) being connected to the said at least one pantograph support structure (21, 22). 9. Concrete mixer truck according to Claim 8, characterised in that the said second control means comprise a pump (71) and at least one fluid cylinder (27) connected to the said pump (71) and having its body supported by the said framework (2) and its rod (26) connected to the said discharge duct (6). 10. Concrete mixer truck according to Claims 4 and 9, characterised in that the said discharge duct (6) is connected to one end of an arm (10) supported by the - said framework (2) for rotation about a substantially vertical axis, and in that the said further control means comprise a handwheel (42) connected to the said arm (10) and arranged, when rotated, to cause an angular displacement of the said arm about the said vertical axis. 11. Concrete mixer truck according to Claim 10, characterised in that it further includes stop means (47, 46, 40, 41) arranged to lock the said handwheel (42) in one or more predetermined angular positions. 12. Concrete mixer truck according to Claims 4 and 9, characterised in that the said discharge duct (6) is connected to one end of an arm (10) supported by the said framework (2) for rotation about a substantially vertical axis, and in that the said further control means comprise a helically toothed wheel (54) connected to the said arm, and a worm (50) coupled together in an irreversible manner.

Inventors: BRUNI, BRUNO
Applicants: BRUNI, BRUNO
Application year: 1982
Main classification: B60P3
IPC codes: B65G11, B28C5