Cement mixer with compact rotating mechanism on swivel-bucket arm

Abstract: A cement mixer with a compact rotating mechanism on the swivel-bucket arm, consisting of a base structure (1), an arm (8) which is rotatable about a horizontal axis (X) relative to the base structure (1) in its bushes (6, 7) and a mixing bucket (12) which is rotatable about a shaft (11) fixed to the arm (8), drive means being provided for rotation of the mixing bucket (12), wherein a further bush (10), which is rotatable with respect to the bush (7) of the base structure (1) and is integral with the arm (8), is arranged integrally at at least one of the two ends of the arm (8), the arm (8) moreover having, directed towards the inside thereof, support means (31, 32) for the drive means for rotation of the mixing bucket (12) which comprise at least one belt (41) which is wound around a considerable portion of the mixing bucket (12) and which is driven by at least one pulley (40) with associated transmission (38,36) driven by a motor means (34).

Description: The present invention relates to a cement mixer with a compact rotating mechanism on the swivel-bucket arm. In the present cement mixers which are currently most used, a swivel bucket is supported on a structure, called an arm, relative to a horizontal axis comprising pairs of end shafts which are arranged in two special bushes. This structure has the possibility of rotating about the horizontal axis, which is common to the two base bushes, and moreover has at one end a bevel pinion which meshes with the teeth of a gearing arranged integrally with the external surface of the bucket. In this way an external motor, via a suitable belt transmission, drives the pinion and causes the rotating movement of the bucket. The high noise level of such a cement mixer is well-known to all; moreover, the said pinion and gearing connection requires time-consuming adjustments to ensure that it is correctly set up. Last but not least it is necessary to consider the danger arising from the presence of moving gears in the zone which is accessible to persons during operation. Finally, perhaps the greatest technical problem is that of providing a safe and low-noise transmission between the motor means and the rotating mixing bucket, taking into account the fact that the rotating bucket must also have a swivel action so that it can be overturned or inclined in accordance with operational requirements. A first technical solution to all these problems has been found by the same Applicants of the present application as per the subject-matter of Italian patent application MI97A002765 filed on 15.12.1997. This cement mixer, although eliminating all of the above problems, has a complex structure and is bulky. DE 1 259 756 B discloses a cement mixer comprising the features of the preamble of claim 1. The object of the present invention is that of providing a cement mixer of this latter type which also overcomes all the abovementioned technical problems of a simple design and structure, in particular with regard to transmission of the movement. Another object of the present invention is that of providing a cement mixer which is able to overcome the drawbacks described above and therefore, in any case, that of providing a cement mixer which has a low noise level and minimum danger factor. These and other objects according to the invention are achieved by providing a cement mixer with a compact rotating mechanism on the swivel-bucket arm in accordance with Claim 1. The characteristic features and the advantages of a cement mixer with a compact rotating mechanism on the swivel-bucket arm according to the present invention will emerge more clearly from the following description, provided by way of a non-limiting example, with reference to the accompanying schematic drawings in which: Figure 1 is a partially sectioned side elevation view of a cement mixer according to the present invention; Figure 2 is a top plan view of the cement mixer according to Figure 1; and Figure 3 is a view, on a larger scale, of a detail shown in Figure 1. With reference to the Figures, these show a cement mixer with a compact rotating mechanism on the swivel-bucket arm for mixing mortar, concrete or various mixtures used in the building sector in accordance with the present invention, denoted in its entirety by 50. This cement mixer essentially consists of a fixed base structure 1 - referred to below as base - resting on the ground by means of wheels with tyres 2 and support legs 3. The top part of the base has, fixed to it integrally, two supports 4 and 5 carrying two bushes 6 and 7 with coinciding horizontal axes. A structure 8, referred to below as arm, has at one end a shaft 9 which is coaxial with the bush 6 and inserted inside it and, at the other end, a bush 10 which is aligned and coaxial with the bush 7. The structure 8 or arm has the possibility of rotating about the horizontal axis, referred to below as axis X, which is common to the two bushes 6 and 7 of the base as well as to the shaft 9 and to the bushes 10 of the arm 8. The arm 8 has, integral with it, in a suitable position vertically with respect to the axis of rotation of the arm, a shaft 11 which is integral with the structure of the arm and on which a mixing bucket 12 of the cement mixer is mounted by means of ball bearings. The bucket 12 therefore has the possibility of rotating about the shaft 11 of the arm 8 and the arm 8 has the possibility of rotating on the supports 4 and 5 about the horizontal axis X of the bushes 6, 7 and 10 and the shaft 9. The end part of one (or two) external component(s) 31 of one (or two) telescopic arms is integrally attached, according to the invention, in a suitable position and in the vicinity of the bush 10, to the inside of the arm 8, alongside the bucket 12. The end part of one (or two) more internal component(s) 32 of the telescopic arm itself, which has the possibility of sliding axially inside the external component 31, is fixed integrally to a sleeve 33. These two components 31, 32 form support means for drive means. These drive means comprise a motor means 34, of the electric, diesel or internal-combustion type, which is fixed to a support bracket 35 in turn fixed integrally in a suitable position to the sleeve 33 and to the internal component 32 of the telescopic arm. This fixing arrangement is formed so that, when the arm 8 rotates about the axis X, the components 31 and 32 of the telescopic component and the support bracket 35 also perform the same rotational movement, integrally and about the axis X. A pulley 36, which is keyed onto one end of the motor 34, transmits the rotational movement of the motor by means of one or more belts 37 to a second pulley 38. This second pulley 38 is keyed to one end of a shaft 39 which is supported by ball bearings inside the sleeve 33. A third pulley 40, which has a diameter smaller than that of the second pulley 38, is keyed to the other end of the shaft 39. Moreover, according to the invention, one or more belts 41 are wound onto the pulley 40 and around a considerable portion of the external surface of the mixing bucket 12, in a central zone with a larger diameter. An element 42 is fixed integrally at one end to the sleeve 33 and at the other end to a bush 43 having the possibility of sliding inside the bush 10 integral with the arm 8. The support bracket 35 for the motor 34 is fixed integrally in a suitable position to the element 42. The external surface of the bush 43 is provided with a thread of suitable pitch so as to receive a nut or a threaded ring 44. By screwing the nut or the threaded ring 44 onto the bush 43, when this nut or ring comes into contact with the end of the bush 10, the bush 43 is axially displaced inside the bush 10 in the direction of the axis X. The axial displacement of the bush 43 causes the axial displacement of the element 42, the internal component 32 of the telescopic arm, the sleeve 33 and the support bracket 35. In this way, by screwing the nut or the ring 44 onto the threaded bush 43, the belts 41 wound onto the external surface of the bucket and onto the pulley 40 are tensioned. Similarly the possibility of tensioning the belts 37 is achieved by means of a tensioning device which is positioned in the vicinity of the support bracket 35 for the motor 34 and schematically indicated by 45 in Figure 2. The motor 34 and all the support structures and mechanisms arranged between the motor and the belts 41 are contained inside a cabinet 46 which is integral with the arm 8. This cabinet has the function of providing protection against adverse weather conditions and of preventing accidents by isolating the moving and movable parts. The body of the cabinet 46 is provided with suitable slits (not shown) so as to allow both any mixing materials conveyed inside by the movement of the belts and any water which may have penetrated to fall to the ground. Moreover the slits provide, at the same time, efficient internal ventilation so as to allow disposal of the heat produced by the motor during operation. The electric power supply cable of the motor 34, in order to pass from the rotating part to the fixed part of the cement mixer on which the stop and start switch is arranged, is introduced inside the bush 43 so as to avoid any possibility of becoming entangled between the fixed parts and the rotating parts of the machine. Starting rotation of the shaft of the motor 34 therefore causes rotation of the bucket 12 with a suitable reduction in speed. Performing, via suitable and conventional actuating and locking devices (not shown), rotation of the arm 8 about the horizontal axis X causes the inclination or overturning of the bucket and rotation about the axis X of all the mechanisms arranged on the arm 8. The pulley 36, the belts 37, the pulley 38, the shaft 39 and the sleeve 33 may alternatively by replaced by a gear reducer or by a simple pair of gears or by a chain and gearwheel transmission which receive the rotational movement from the motor and transmit it, suitably reduced, to the belts wound onto the external surface of the bucket. The present invention has provided a swivel-bucket cement mixer for mixing mortar, concrete or various mixtures used in the building sector, which is operated by a motor of a suitable nature provided with a system for transmission of the movement from the motor to the bucket, with an entirely novel and original design. This cement mixer, in addition to overcoming the general complications of the known art, also undoubtedly has particular features which are advantageous and useful. In fact, compared to a solution in which the bucket 12 was also moved by means of belts, with this new technical solution a series of advantages is possible. It has a constructional simplicity with a consequent reduction in the working times and materials used and in turn a consequent reduction in the production costs. It allows elimination of all the belt drive rollers of the preceding solution, which were subject to a significant degree of mechanical stress and which, being arranged in a necessarily unprotected position, represented a probable source of malfunction. It results in elimination of fatigue stressing of the belts which, in the preceding solution, being wound first in one direction and then in the opposite direction, were subject to rapid deterioration. In this new solution there is the possibility of performing adjustment of the tension of the bucket-pulley belts without the need for access to the inside of the motor protection cabinet. And this operation is now possible also with the bucket in movement, without exposing the operator to the risk of getting caught by the rotating parts inside the drive cabinet. Provision of the drive system inside the arm results in a reduction in the overall length of the cement mixer. This saving in space allows the loading of a greater number of machines onto the platform of a motor vehicle and consequently a reduction in the costs of transportation of the cement mixers. Without doubt, the machine is less noisy as a result of the reduction, to a minimum, of the number of moving parts.

Claims: A cement mixer with a compact rotating mechanism on the swivel-bucket arm, consisting of a base structure(1),an arm(8)which is rotatable about a horizontal axis (X) relative to said base structure (1) in its bushes (6,7) and a mixing bucket (12) which is rotatable about a shaft(11) fixed to said arm(8), drive means being provided for rotation of said mixing bucket (12), characterized in that a further bush (10), which is rotatable with respect to said bush(7)of the base structure (1) and is integral with said arm (8), is arranged integrally at at least one of the two ends of said arm (8), said arm (8) moreover having, directed towards the inside thereof, support means (31,32) for said drive means for rotation of said mixing bucket (12) which comprise at least one belt (41) which is wound around a considerable portion of said mixing bucket (12) and which is driven by at least one pulley (40) with associated transmission (38,36) driven by a motor means(34), said motor means (34) is fixed to a support bracket (35) which is in turn fixed integrally to a sleeve (33) displaceable in an adjustable manner with respect to said bush (10), said sleeve (33) is integral with a bush (43) having a threaded end which engages with a ring or nut (44) located on the other external side of said bush (10). Cement mixer according to Claim 1, characterized in that said arm(8)carried said transmission comprising one or more belt drives (37) and pulley (36,38) for transmitting the rotational movement, suitably reduced, to said mixing bucket (12). Cement mixer according to Claim 1, characterized in that said arm (8) carrying said bucket (12), said motor means (34) and said transmission from said motor-means to said bucket rotate integrally together about said horizontal axis (X). Cement mixer according to Claim 1, characterized in that said at least one belt (41) for transmission of the rotational movement to said bucket (12) is wound directly onto an external surface of said bucket. Cement mixer according to Claim 1, characterized in that said support means (31, 32) for said drive means comprise two telescopic components, one (32) being fixed on one side to a sleeve (33) which carries said at least one pulley (40) and the other (33) being fixed on the other side to said arm (8). Cement mixer according to Claim 1, characterized in that said drive means for rotation of said mixing bucket (12) are arranged inside a cabinet (46) integral with said arm(8). Cement mixer according to Claim 6, characterized in that said cabinet (46) comprises associated slits.

Inventors: CERUTTI CARLO, CERUTTI, CARLO
Applicants: SAN MARCO INTERNAT S R L, SAN MARCO INTERNATIONAL S.R.L.
Application year: 1999
Main classification: B28C5
IPC codes: B28C5