GB2112292A

GB2112292A - A concrete mixer

Info

Publication number: GB2112292A
Application number: GB08231498A
Authority: GB
Inventors: Ian Victor Murphy; Alfred Anthony Cox
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-11-04
Filing date: 1982-11-04
Publication date: 1983-07-20
Also published as: IE812578L; GB2112292B

Abstract

The mixer is self-loading through a pick-up scoop 60, 84 extending around the axis of rotation of the drum 2,81 from an in let mouth 61,88 projecting radially beyond the periphery of the drum 2 to a discharge opening 62, 89 into the drum. A flap 70 is pivotally mounted in the scoop 60, 84 to prevent material flowing back through the scoop on rotation of the drum. In one version the outer wall 63 of the scoop 60 extends around the axis of rotation of the drum 2 to abut the periphery of the drum behind the discharge opening 62 and in an alternative construction the scoop is formed from an enclosed duct 84 having an outer wall 85 which extends within the periphery of the drum 81. In operation, the drum 2 is rotated over a mound of material which is directly into the scoop 60, 84 through the inlet mouth 61, 88 and into the drum through the discharge opening 62, 89. <IMAGE>

Description

SPECIFICATION A concrete mixer The invention relates to a concrete mixer and in particular to a self-loading tractor-mountable concrete mixer.

There are three principal types of concrete mixer known: large capacity permanent concrete plants: medium capacity truck-mounted mixers; and small capacity on-site mixers. Generally, these mixers are externally loaded, from hoppers using feed chutes in the case of concrete plants and truck-mounted mixers, or manually loaded with a shovel in the case of the smaller on-site mixers.

One disadvantage associated with the small site mixers is that considerable manual labour is required to load the mixer. In addition, the output capacity of such mixers is generally limited by virtue of their small size and/or the time taken to fill and mix a load. Another, less significant, disadvantage is that they are not easily transportable without the use of a crane.

One of the objects of this invention is to provide a concrete mixer with increased output capacity and which is readily transportable.

According to the invention there is provided a concrete mixer comprising a pivotally and rotatably mounted mixing drum having an opening at one end thereof and a pick-up scoop extending around the axis of rotation of the drum from an inlet mouth projecting radially beyond the periphery of at least that portion of the drum forward of the scoop to a discharge opening into the drum.

In one embodiment of the invention the scoop includes an outer wall extending around the axis of the drum to abut the periphery of the drum behind the discharge opening formed by a hole in the drum.

Preferably, the scoop has side walls extending between the outer wall and the periphery of the drum.

In another aspect the invention provides a concrete mixer comprising a pivotally and rotatably mounted mixing drum having an opening at one end thereof and a pick-up scoop formed from an enclosed duct extending around the axis of rotation of the drum, from an inlet mouth projecting radially beyond at least that portion of the periphery of the drum forward of the duct to a discharge opening into the drum, the duct having an outer wall which extends from the inlet mouth to a position on or within the periphery of the drum.

In another embodiment of the invention the scoop is formed from an enclosed duct, having an outer wall which extends from the inlet mouth to a position on or within the periphery of the drum.

Preferably, the axial dimension of the duct decreases from the inlet mouth to the discharge opening and the area of the inlet mouth is less than the area of the discharge opening. Ideally, the area of the inlet mouth is substantially less than the area of the discharge opening.

Typically, the periphery of the drum forms part of the scoop. Usually, the scoop has an inner wall which extends beyond the outer wall into the drum.

In one preferred arrangement a closure flap is pivotally mounted in the scoop. Usually, the flap is pivotally mounted in the scoop adjacent the inlet mouth, the flap being pivotal from an open position when material is being picked up by the scoop, to a closed position when material is being delivered into the drum through the discharge opening.

Alternatively, the flap is pivotally mounted in the scoop adjacent the discharge opening, the flap being pivotal on rotation of the drum from an open position for delivery of material into the drum to a closed position preventing discharge of material from the drum.

The drum may include a main frusto-conical portion and the inlet mouth may extend axially along substantially the length of the frusto-conical portion.

Preferably, the drum is pivotal from a lower loading position in which the drum rotates to pickup and lift material into the drum, through an upper, intermediate mixing position, to a lower drum delivery position in which mixed material is discharged through the opening in the end of the drum.

In a further embodiment of the invention, the drum is rotatably mounted on a mounting chassis, the chassis being pivotally mounted on an inverted T-frame, and articulating means are provided between the chassis and the T-frame for pivotal movement of the drum.

Preferably, the articulating means comprises a single acting hydraulic ram.

In one particularly preferred aspect of the invention, the extremities of the inverted T-frame are connected to the three point linkage of a tractor, the drum is driven by the power take-off shaft of the tractor and the ram is operated from the hydraulic system of the tractor.

In an alternative aspect of the invention, the drum is mounted on the front lifting arms of a loader.

The invention also provides a tractor incorporating such a concrete mixer.

The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view, from the front of a concrete mixer according to one embodiment of the invention, Fig. 2 is a sectional view in the direction of the arrows Il-Il in Fig. 1, Fig. 3 is a detailed sectional view of portion of the mixer illustrated in Fig. 2, Fig. 4 is a perspective, partially cut-away view of a mixer with a different construction of scoop, and Fig. 5 is a sectional view in the direction of the arrows V-V in Fig. 4.

Referring to the drawings, there is illustrated a concrete mixer indicated generally by the reference numeral 1. The mixer 1 comprises a drum 2 mounted for rotation about a longitudinal axis of rotation on a mounting chassis 3 connected to an inverted T-frame support 5 through a pivot connection 7. The angle of inclination of the drum 2 relative the ground is variable through the action of a ram 10 connected between the chassis 3 and the T-frame support 5 and the T-frame support 5 is mounted on the three point linkage of a tractor (not shown) for raising and lowering of the drum 2. The ram 10 is hydraulically or pneumatically operated, for example from the hydraulic system of a tractor, and the drum 2 is rotated from the power take-off shaft (only portion, 11 of which is shown in Fig. 1) through a drive train 12.

In detail, the drum 2 is rotatably mounted on an axle 20 extending longitudinally through the centre of the drum 2 and journaled in bearings 21 on the mouting chassis 3. The drum 2 is rotated from the power take-off shaft 11 of the tractor through the drive train 1 2 which comprises a toothed pinion wheel 22 intermeshed with a large toothed gear wheel 23 fast on the drum axle 20, the pinion wheel 22 being driven from the power take-off shaft 11 through a drive shaft 24 arranged at right angles to the axle 20. The power take-off shaft 11 is connected to the drive shaft 24 through a universal joint 25 which accommodates relative movement between the two shafts 11,24.

The chassis 3 is formed from a pair of transverse support members 30 arranged at right angles to the drum axle 20, cantilevered to a longitudinal support member 31, the members 30, 31 forming a U-shaped drum embracing frame.

In detail, the inverted T-frame support 5 is formed from an upright strut 33 mounted on a base member 34 having ground engaging legs 35 supporting the chassis 3, the longitudinal member 31 of the chassis 3 being pivotally connected to the strut 33 adjacent the cylindrical portion 13 of the drum 2 through the pivot connection 7. The strut 33 and case member 34 are joined by triangular reinforcing supports 37 which add rigidity to the T-frame 5. The upper end of the strut and the extremities of the base member 34 are formed with links 38, 39, 39(a) for connection to the top link and bottom links respectively of the three point linkage of a conventional tractor (not shown). In some cases it may be necessary to provide an extension arm on at least the top link of the tractor three point linkage to facilitate lowering and raising of the mixer as required.This extension in its simplest form may be provided by a metal bracket or by a hydraulically retractable connector which is extendable under the weight on the drum. It should also be free to float in the event of striking an obstacle.

The ram 10 comprises a piston shaft 40 slidable in a cylindrical housing 41. Actuation of the ram 10 by the hydraulic system of the tractor causes the piston shaft 40 to extend, which pivots the chassis 3, and hence the drum 2 in the direction of the arrow A in Fig. 1, about the pivot connection 7. Calibration lines (not shown) are provided on the shaft 40 so that the angle of the mixing drum 2 with respect to the ground may be set by extending the shaft 40 a pre-set amount from its housing 41.

Referring particularly to Figs. 1 to 3, the drum 2 includes a first frusto-conical portion 50, an interconnected second frusto-conical portion 51 the cone angle of the first portion 50 being larger than the second portion 51, a closed end 52 and an open end defining an opening 53 through which water and other material may be introduced into the drum 2 and more particularly, through which mixed material may be discharged from the drum 2. A pick-up scoop 60 is mounted on the first portion 50 adjacent the closed end 52 and extends around the longitudinal axis of rotation of the drum 2 from an inlet mouth 61 projecting radially beyond the periphery of the drum 2 forward of the scoop 60 to a discharge opening 62 into the drum 2.The scoop 60 includes an outer wall 63 extending around the axis of the drum 2 for approximately one-quarter the periphery of the cylindrical portion 50 and is curved inwardly at its rearward end 64 to abut the periphery of the drum behind the discharge opening, which in this case is formed by a rectangular hole 62 in the drum 2. In this instance, the scoop 20 is an enclosed scoop having side walls 65 extending between the outer wall 63 and the periphery of the drum 2. A closure flap 70 is pivotally mounted on pivot pins 71 in the scoop 60, in this case adjacent the inlet mouth 61. The flap 70 is provided with a U-shaped push bar 72 joined at its extremities to the body of the flap 70.

The bar 72 diverges outwardly from the flap 70 at an angle of approximately soa and is lightly spring biased by a coil spring 75 joined at one end to the flap 70 and at the other end to the outer wall 79 of the scoop 60. On rotation of the drum during loading, material bears against the push bar 72 to open the flap 70 (the open position of the flap is illustrated by interrupted lines in Fig. 3) against the biasing of the spring 75 and hence allow material to be introduced through the scoop 60 and discharge opening 62 into the drum 2. When the drum 2 rotates out of engagement with the material the flap returns to the closed position under the biasing of the spring 75 to prevent materi falling back out of the scoop 60. A slot 79 is provided in the outer wall 63 of the scoop 60 to allow any material which may retain in the scoop after the flap 70 is closed to be discharged from the scoop 60.

In use, the drum 2 is initially set from the tractor cab at a lower loading position by extending the ram 10 to the desired position as noted by the appropriate calibration line on the shaft 40. The tractor is then manoeuvred until the scoop 60 is positioned over a heap of material, which may be aggregate, sand and/or cement to be fed into the drum 2. The throttle of the tractor is set so that the power take-off shaft rotates at a speed of 540 revoiutions per minute (r.p.m.) which is stepped down through the drive train 12 so that the drum 2 rotates in the direction of the arrow B at a speed of 37 r.p.m. This speed corresponds to the minimum throttle on a conventional tractor. The drum 2 is then lowered over the heap of aggregate by lowering the control arms of the three point linkage until the scoop 60 is adjacent the top of the heap.The drum 2 is rotated and material is delivered into the inlet mouth 61 of the scoop where it bears against the push bar 72 of the flap 70 to open it against the biasing of the spring 75 and allow the aggregate to flow down the scoop as the drum rotates. When the weight of material against the push bar 72 is reduced as the inlet mouth 61 rotates away from the heap of material, the flap 70 closes under the biasing of the spring 35.

As the drum continues to rotate the material falls under the action of gravity into the drum 2 through the discharge opening 62. Any material remaining in the inlet mouth of the scoop when the flap 70 closes falls out through the slot 79.

When the drum has turned through one revolution all the material picked up by the scoop will be discharged into the drum and the inlet mouth 61 is positioned just over the mound of material ready to pick up further material. Continued rotation of the drum fills the drum 2 to the level where material begins to emerge from the end opening 53. The mixer 1 is raised by raising the hydraulic lifting arms of the tractor to prevent further material being loaded into the drum 2 and is pivoted into an upper, intermediate mixing position as indicated by the appropriate calibration line and the piston shaft 40 at an angle of 300 to the ground by extension of the ram. In this position the appropriate quantity of cement and/or water may be introduced into the drum 2 through the opening 53.Rotation of the drum 2 is continued until mixed concrete of the desired consistency is obtained and the concrete is delivered from the drum 2 through the opening 53 by extending the ram 10 fully to pivot the drum 2 into discharging position with the closed end 52 of the drum 2 uppermost. To return the drum 1 to its loading position, the supply of hydraulic fluid to the ram 10 is cut-off, allowing the drum 2 to pivot about the pivot connection 7 under its own weight.

Referring to Figs. 4 and 5 there is illustrated an alternative construction of mixer indicated generally by the reference numeral 80. The mixer 80 is similar to that described above with reference to Figs. 1 to 3 and like parts are identified by the same reference numerals however, for iliustrative purposes the drum support, the flap, and the end closure plate of the drum have been omitted from the drawings. The mixer 80 comprises a drum 81 closed at one end 83 and open at the other end to provide an opening 82 simiiar to the opening 53 in the drum of Figs. 1 to 3. The scoop in this case comprises an enclosed duct 84 having an outer wall 85, an inner wall 86, side walls 87 spaced-apart to define an inlet mouth 88 at one end and a disharge opening 89 at the opposite end.The duct 84 is shaped to extend through a peripheral opening in the drum 2 so that the outer wall 85 extends from the inlet mouth to a position on the periphery of the drum while the inner wall 86 extends beyond the outer wall 85 into the drum 81 to provide a lip 90 which helps prevent material falling back into the scoop from the drum. Portion of the centre wall 85 could be cut-away so that the periphery of the drum forms part of the outer wall 85 of the duct 84.

The drum 81 comprises a main first frustoconical portion 91 and a second frusto-conical portion 92, the cone angle of the second portion 92 being greater than that of the first 91. The duct 84 is mounted on the first portion 91 adjacent the closed end 83 and the leading edge of the outer wall 85 of the duct 84 is substantially parallel to the periphery of the first portion 91, which during loading is arranged parallel to the ground. This position of the inlet mouth of the duct facilitates pick-up of material into the scoop.

The inlet mouth 88 extends along substantially the length of the first frusto-conical portion 91 of the drum 81 to provide a large area through which material may be delivered into the drum. The side walls 87 of the duct 84 converge and the inner and outer wall 86, 85 diverge from the inlet mouth 88 to the discharge opening 89 so that the axial dimension of the duct 84 decreases, and the other, substantially radial dimension, increases along the duct 84. However, the area of the inlet mouth 88 is less than the area of the discharge opening 89. For illustrative purposes the area of the mouth 88 is shown in Fig. 4 relatively larger than that of the opening 89. The area of the mouth 88 may be substantially less than that of the opening 89 for maximum pick-up and free flow of material through the duct.

One advantage of the invention is that the self loading operation of the mixer is significantly faster than manual loading and hence the time taken to mix a load is decreased over present site mixers and thus the output of the mixer is substantially increased. In addition, because the mixer may be conveniently mounted on a tractor it is readily transportable.

It will be appreciated that the scoop does not necessarily have to be an enclosed scoop. Indeed, to assist the free flow of material into the drum it may be advantageous to leave the sides of the scoop open. For example, the scoop could be formed from a plate extending forwardly from behind the discharge opening into the drum to define together with the periphery of the drum an inlet mouth. The plate may extend for any length around the axis on the drum. However, a plate extending circumferentially for approximately one quarter the periphery of the drum has been found to be particularly advantageous with enclosed scoops.

It will also be appreciated that instead of, or in addition to providing a flap at the inlet mouth, a closure flap may be provided adjacent the discharge opening into the drum. In this case, it is envisaged that the flap would not require to be spring biased but would operated under gravity on rotation of the drum from an open position for delivery of material into the drum to a closed position preventing discharge of material from the drum.

It is envisaged that many other arrangements may be used for mounting the drum to allow it to rotate and pivot as required. For example, both ends of the drum may have cross-beams to provide a mounting means for a sub-axle located at the centre of both ends of the drum and the axle could be driven through appropriate gearing to eliminate the need for an axle extending through the drum. In pivoting the drum the articulating means could comprise a double-acting hydraulic or pneumatic ram.

It will also be appreciated that while the mixer has been described as tractor-mounted, it could also be mounted on any appropriate means such as the front lift arms of a loader, to facilitate raising and lowering the drum and hence discharge directly into shuttering for casting in situ.

It will further be appreciated that for ease of cleaning the scoop may be readily detachable from the drum or means may be provided for cleaning the inside of the scoop, for example in the case of an enclosed scoop the side walls may be easily removable.

It will also be appreciated that the drum may be driven by an hydraulic motor. The drive may be a direct drive mounted on the end of the drum or an indirect drive through a chain and sprocket arrangement or gearing. The drive may also incorporate a gear reduction unit.

The arms 30 of the chassis may be provided with skids projecting downwardly beyond the outer periphery of the drum to present the drum being rotated when resting on the ground.

It is envisaged that at least the leading edge of the scoop will be reinforced to prevent excessive wear.

Claims

1. A concrete mixer comprising a pivotally and rotatably mounted mixing drum having an opening at one end thereof and a pick-up scoop extending around the axis of rotation of the drum from an inlet mouth projecting radially beyond at least that portion of the periphery of the drum forward of the scoop to a discharge opening into the drum.

2. A mixer as claimed in claim 1 in which the scoop includes an outer wall extending around the axis of the drum to abut the periphery of the drum behind the discharge opening formed by a hole in the drum.

3. A mixer as claimed in claim 2 in which the scoop has side walls, extending between the outer wall and the periphery of the drum.

4. A concrete mixer comprising a pivotally and rotatably mounted mixing drum having an opening at one end thereof and a pick-up scoop formed from an enclosed duct extending around the axis of rotation of the drum, from an inlet mouth projecting radially beyond at least that portion of the periphery of the drum forward of the duct to a discharge opening into the drum, the duct having an outer wall which extends from the inlet mouth to a position on or within the periphery of the drum.

5. A mixer as claimed in claim 1 in which the scoop is formed from an enclosed duct, having an outer wall which extends from the inlet mouth to a position on or within the periphery of the drum.

6. A mixer as claimed in claim 4 or 5 in which the axial dimension of the duct decreases from the inlet mouth to the discharge opening and in which the area of the inlet mouth is less than the area of the discharge opening.

7. A mixer as claimed in claim 6 in which the area of inlet mouth is substantially less than the area of the discharge opening.

8. A mixer as claimed in claim 7 in which the periphery of the drum forms part of the scoop.

9. A mixer as claimed in any of claims 4 to 8 in which the scoop has an inner wall which extends beyond the outer wall into the drum.

10. A mixer as claimed in any preceding claim in which a closure flap is pivotally mounted in the scoop.

11. A mixer as claimed in claim 10 in which the flap is pivotally mounted on the scoop adjacent the inlet mouth, the flap being pivotal from an open position when material is being picked up by the scoop, to a closed position when material is being delivered into the drum through the discharge opening.

12. A mixer as claimed in claim 10 in which the flap is pivotally mounted in the scoop adjacent the discharge opening, the flap being pivotal on rotation of the drum from an open position for delivery of material into the drum to a closed position preventing discharge of material from the drum.

13. A mixer as claimed in any preceding claim in which the drum includes a main first frustoconical portion and the inlet mouth extends axially along substantially the length of the frusto-conical portion.

14. A mixer as claimed in any preceding claim in which the drum is pivotal from a lower loading position in which the drum rotates to pick-up and lift material into the drum, through an upper, intermediate mixing position, to a lower drum delivery position in which mixed material is discharged through the opening in the end of the drum.

1 5. A mixer as claimed in any preceding claim in which the drum is rotatably mounted on a mounting chassis, the chassis being pivotally mounted on an inverted T-frame, and articulating means are provided between the chassis and the T-frame for pivotal movement of the drum.

1 6. A mixer as claimed in claim 1 5 in which the articulating means comprises a single acting hydraulic ram.

17. A mixer as claimed in claim 16 in which the extremities of the inverted T-frame are connected to the three point linkage of a tractor, the drum is driven by the power take-off shaft of the tractor and the ram is operated from the hydraulic system of the tractor.

18. A mixer as claimed in any of claims 1 to 16 in which the drum is mounted on the front lifting arms of a loader.

1 9. A tractor incorporating a mixer as claimed in any of claims 1 to 17.

20. A mixer as claimed in any of claims 1 to 18 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

21. A mixer substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.