GB2236260A

GB2236260A - Concrete mixing vehicle

Info

Publication number: GB2236260A
Application number: GB8922048A
Authority: GB
Inventors: Peter Hale
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-09-29
Filing date: 1989-09-29
Publication date: 1991-04-03
Also published as: GB8922048D0

Abstract

A concrete-mixing vehicle comprises a lorry chassis 10 having a driving cab 11 behind which is a first container 12 for ballast and behind that a second container 13 for cement, a water tank 22 being mounted in the first container. A relatively small concrete-mixing drum 27 having its own engine 30 is mounted on a sub-frame 26 attached to the chassis, which drum is below a conveyer 15 running below the containers 12 and 13. Gates are arranged at the bottom of the containers for controlling the supply of materials from the containers on to the conveyer 15. <IMAGE>

Description

CONCRETE MIXING VEHICLE This invention relates to a vehicle adapted and configured for the mixing and discharge of concrete.

Such a vehicle will hereinafter be referred to as a II "concrete mixing vehicle".

A known form of self-propelled concrete mixing vehicle comprises a lorry chassis having a forward driving cab, behind which there is mounted on the chassis a concrete mixing drum with its axis at some fixed angle to the horizontal. The drum is rotatable about its axis and is able to carry typically from 2 m3 for the smaller vehicles, up to 6 m3 for the larger vehicles. Such vehicles may have an independent engine to rotate the drum, or the drum may be driven by a power take-off arrangement, from the main engine of the vehicle. The vehicle includes a discharge mechanism associated with the drum, to allow the drum contents to be discharged as and where required, but also to allow rotation of the drum without any discharge taking place, so that the drum contents may continuously be mixed, as the vehicle is under way.

Concrete mixing vehicles of the kind described above are used extensively in the construction industry, from relatively small projects right through to very large scale works. Despite that, a disadvantage of the use of such vehicles is that an accurate assessment must be made of the amount of concrete required in advance of a delivery being effected: if too little is ordered it may be impossible to complete a job properly and within a required time scale, but on the other hand if too much is ordered, this leads to unnecessary expense and waste, coupled with the problem of disposing of the excess concrete. In addition, a large scale batching plant must be provided for feeding such vehicles, an appropriate cement/ballast mix being prepared in the batching plant, and then the required volume of that mix is then supplied dry to the drum of a concrete mixing vehicle.Water may be added to that mix in the drum, and mixing is continued by rotating the drum, as the vehicle is driven to the required discharge site.

It is a principal aim of the present invention to provide a concrete mixing vehicle wherein relatively small batches of concrete may be mixed as and when required, and which vehicle does not require the provision of a separate batching plant, for the supply thereto of a cement/ballast mix.

Accordingly, this invention provides a concrete mixing vehicle, comprising a wheeled chassis on which is mounted a first container for holding ballast, a second container for holding cement, a tank for holding water, a power-driven mixing drum, and feed means arranged to feed ballast and to feed cement from the respective containers therefor to the drum, to allow the mixing of ballast and cement within the drum.

It will be appreciated that with the vehicle of this invention, the vehicle separately carries both cement and ballast, and that the cement and ballast are drawn from the respective containers therefor and mixed within the mixing drum, only as and when required.

Since the vehicle carries both the cement and ballast separately, for a given chassis size the power-driven mixing drum inevitably must be considerably smaller than would be the case with a conventional concrete mixing vehicle as described above - but that in turn is an advantage, in that relatively small batches of concrete may be mixed precisely to suit the demand. As a consequence, though the concrete mixing vehicle of this invention may not be best suited for use in connection with large-scale construction works, nevertheless the vehicle is much more suitable for use with small-scale projects, such as housing construction, extensions and so on.

Most preferably, the wheeled chassis comprises a self-propelled lorry chassis including a driving cab.

Such a chassis may be similar in construction and loadcarrying capacity to those associated with conventional concrete mixing vehicles, described above. However, on the chassis and behind the driving cab, there should be mounted the first and second containers, preferably disposed one in front of the other, and with the ballast container having a volume typically 3 to 5 times as great as the cement container. The tank for holding water may be disposed immediately behind the driving cab, and may conveniently be disposed within the ballast container, at the forward end thereof.

The power-driven mixing drum preferably has a capacity in the range of from 0.18 m3 to 0.20 m3. Such a mixing drum may be mounted on a sub-frame attached to the rear of the vehicle chassis, at a relatively low level. Moreover, the drum may be pivotable about a horizontal axis extending at right angles to the axis of rotation of the drum, whereby the drum may be tipped between a cement and ballast receiving position where the mouth of the drum faces generally upwardly, below the feed means through a mixing position to a discharge position, where the mouth of the drum faces generally downwardly. A separate motor may be provided to effect rotation of the drum, about its own axis, or in the alternative, a suitable power drive arrangement may be provided, from the main vehicle engine.

The feed means preferably comprises a belt conveyer assembly disposed below the ballast and cement containers, suitable gates being provided on both the ballast and cement containers to control the feed of ballast and cement respectively, on to the belt.

Metering arr-angements, such as power driven Archimedian screws, may be disposed in the lower portions of the containers, to assist discharge of the ballast and cement on to the conveyer, and to control the volume supply thereof.

By way of example only, one specific embodiment of concrete mixing vehicle constructed and arranged in accordance with this invention will now be described in detail, reference being made to the accompanying drawings, in which: Figure 1 is a diagrammatic side view of said embodiment of concrete mixing vehicle; and Figure 2 is-a diagrammatic rear view of the concrete mixing vehicle of Figure 1.

Referring to the drawings, there is shown a threeaxle lorry chassis 10 having a driving cab 11 disposed generally at the forward end of the chassis, over the engine. On the load-bearing part of the chassis 10, there is provided a first container 12, and behind that first container there is provided a second container 13, these two containers being supported on the chassis by means of suitable brackets to provide a gap between the undersides of the containers and the principal chassis members 14. Within this gap there is disposed a longitudinally-extending endless belt conveyer 15, including rollers 16 and an hydraulic motor 17.

Hydraulic fluid under pressure is supplied to motor 17 from a conventional form of pump assembly (not shown) driven by the main engine of the vehicle chassis, in a manner well known in the art.

Within the base of the second container 13, there is provided a transverse Archimedian screw 18, driven by a motor 19. An aperture 20 is provided in the base of the second container 13, below the screw 18, and a separate shutter assembly 21 is arranged to allow opening and closing of the aperture 20 in the base of the container. Material contained in the container 13 may thus be deposited on the conveyor by operating the shutter assembly 21 to open the aperture 20, and operating the screw 18.

The first container 12 has an elongate slot (not shown) extending lengthwise in the container base wall, above the belt conveyer 15, that slot being provided with a further shutter assembly (not shown), to allow the opening and closing of that slot. In this way, the depositing of the material contained in the container may be controlled.

A water tank 22 is disposed within the first container 12, at the forward end thereof and in an elevated position. That tank 22 has a pipe 23 leading towards the rear of the vehicle, which pipe is fitted with a stop-cock 24 and is coupled to a hose wound on a reel 25.

A sub-frame 26 is attached to the rear of the vehicle chassis and carries a mixing drum 27, the drum being mounted for rotation about the drum axis and being supported by a pivoting carrier 28 allowing the drum to be tilted about a horizontal axis extending transversely of the vehicle. Such tilting movement is controlled by a hand wheel 29, and a separate motor 30 is provided to effect rotation of the drum, about its own axis.

The drum 27 has a volume of approximately 0.19 m3, and the drum is so-dimensioned that it may be disposed as shown in Figure 1, with its mouth 31 below the rear end of the conveyer 15, to receive ballast and cement discharged from the belt conveyer 15. From there, the mixing drum may be pivoted in a counter-clockwise manner (in Figure 1) to a mixing position, and from there the drum may be further pivoted counter-clockwise to a position where the contents of the drum may be discharged.

In use, the first and second containers 12 and 13 are filled with appropriate grades of ballast and cement, respectively, having regard to the nature of a given construction and the water tank 22 is filled with water. The vehicle is then driven to the site where the concrete is required, and the drum 27 is then filled with both cement and ballast, in the required proportions. This is achieved by opening the shutter assemblies associated with the containers, and operating the conveyer 15. The proportioning of the ballast and cement may be performed by appropriate use of the shutter assemblies, and screw 18, though it may be sufficient to use simple volumetric proportioning - for example, manually using a spade or a large container, to Another possibility is for the drum to be marked both internally and externally, to indicate various volumentric filling capacities.

Once filled, as required, the drum 27 is then rotated to mix the ballast and cement, and at the same time water and any other additives may be fed into the drum, to provide the required concrete mix. Once the vehicle has been positioned adjacent the discharge site, the drum is tilted to discharge the first batch of mixed concrete. This procedure may be continued until the particular works are complete - and it will be appreciated that only the exact amount of concrete need be mixed, without there being any waste.

A further advantage of the concrete mixing vehicle described above is that the sub-frame 26 may readily be detached from the chassis 10, and then the belt conveyer 15 operated in conjunction with the opening of at least one of the shutter assemblies, either to discharge just ballast, or a dry mix of ballast and cement, from containers. The vehicle may even be driven over a trench, continuously to discharge a lean dry mix over groundworks in such a trench, without the need need to use the mixing drum 27 whatsoever.

Claims

1. A concrete mixing vehicle comprising a wheeled chassis on which is mounted a first container for holding ballast, a second container for holding cement, a tank for holding water, a power-driven mixing drum, and feed means arranged to feed ballast and to feed cement from the respective containers therefor to the drum, to allow the mixing of ballast and cement within the drum.

2. A concrete mixing vehicle according to Claim l, wherein the wheeled chassis comprises a self-propelled lorry chassis including a driving cab.

3. A concrete mixing vehicle according to Claim 2, wherein the first and second containers are disposed one in front of the other, the ballast container having a volume of 3 to 5 times as great as the cement container.

4. A concrete mixing vehicle according to Claim 3, wherein the tank for holding water is disposed within the ballast container, at the forward end thereof.

5. A concrete mixing vehicle according any of the preceding Claims, wherein the power-driven mixing drum has a capacity in the range of from 0.18 m3 to 0.20 m3.

6. A concrete mixing vehicle according to any of the preceding Claims, wherein the mixing drum is mounted on a sub-frame attached to the rear of the vehicle chassis, at a relatively low level.

7. A concrete mixing vehicle according to any of the preceding Claims, wherein the drum is pivotable about a horizontal axis extending at right angles to the axis of rotation of the drum, whereby the drum may be tipped between a cement and ballast receiving position where the mouth of the drum faces generally upwardly, through a mixing position to a discharge position, where the mouth of the drum faces generally downwardly.

8. A concrete mixing vehicle according to any of the preceding Claims, wherein a separate motor is provided to effect rotation of the drum, about its own axis.

9. A concrete mixing vehicle according to any of the preceding Claims, wherein the feed means comprises a belt conveyer assembly disposed below the ballast and cement containers, with respective gates being provided on both the ballast and cement containers to control the feed of ballast and cement on to the belt.

10 A concrete mixing vehicle according Claim 9, wherein metering means are disposed in the lower portions of the containers, to assist discharge of the ballast and cement on to the conveyer, and to control the volume supply thereof.

11. A concrete mixing vehicle according to Claim 10, wherein the metering means of each container comprises an Archimedian screw.

12. A concrete mixing vehicle according Claim 1 and substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.