The object of the invention is a system for spreading a wet mass, which consists of a vehicle and a tank carried by it for the temporary storage of e.g. asphalt, concrete, or oil gravel, and a spreader section for spreading the mass over the surface of a base. The invention intended in particular for spreading asphalt or oil gravel, but is also applicable to the spreading of concrete. Here a wet mass means mainly asphalt and concrete masses, but may equally well concern other masses requiring to be spread, and which tend to adhere to the surfaces of the equipment.

US patent publication 3,820,914 shows a truck intended for the manufacture and repair spreading of asphalt, which is equipped with two tanks for bitumen and mineral substances. The system includes a complicated mixing equipment with a screw conveyor. From the point of view of cleaning and maintenance the solution is unsatisfactory. The manufacture of the mass in the spreader vehicle itself considerably slows the spreading work as such.

In general a machine specially designed for the purpose is used for spreading asphalt mass used as a road surface. A mass spreader of this kind is an essential machine both for the flexible treatment of the mass, and from the point of view of the high quality of the surface. The principal components of the asphalt spreader are a tractor section and a gliding section attached to it by a drawbar. The tractor section pulls the glider or spreading bar behind it, and at the same time pushes a truck in front it, which raises its bed to discharge it load of mass onto the spreader. In tractor section includes in addition a box-like mass reception funnel, two pusher conveyors and portioning opening to move the mass forwards, as well as two screw conveyors or spirals, which move the mass laterally, so that it comes in front of the glider over its entire length for forming and levelling.

Present types of asphalt spreader systems cannot work in rain, because rainwater mixing with the mass reduces its quality. The asphalt mass is transported from the asphalt station by ordinary

trucks, which tip their load into the silo of the asphalt spreader. Even though a cover is always used on top of the mass during transportation, the surface of the hot mass always oxidizes to some extent, which corresponds to several years aging on a road. One problem in handling asphalt is grading, which the separation of the different fractions, first of all when the mass is loaded onto the bed of the truck, and secondly when it is tipped from the bed into the silo of the spreader.

At present the distance of the asphalt station from the point of work is quite limited, because the storage silo of the asphalt spreader is very small and must be filled often.

The transportation and temporary storage of a concrete mass demand its continual mixing. In addition the aforementioned known devices are difficult to service and clean.

The intention of this invention is to create a new type of mass spreader system, with a greater efficiency than before. This means a smaller transportation capacity and a greater possible distance from the asphalt station. In addition the system in accordance with the invention reduces the oxidation referred to above, or the problems relating to grading. The system in accordance with the invention is easy to maintain and the washing of the equipment causes no problems. The characteristic features of a wet mass spreading system in accordance with the invention are presented in Patent Claim 1. From the point of view of the invention it is essential that closed, cylindrical tanks, which are equipped with internal spirals to move the mass from the front to the back, are used. A system of this kind is easy to maintain and clean, because it contains only a few moving parts. The oxidation of the mass in a cylindrical tank is less than in an open tank. In addition, the work of spreading the asphalt can also be carried out in rain. In accordance with the invention, the tank of the spreading machine itself can be made large, in which case a large transportation truck can also be used, which is able to fetch the mass from quite far away.

A spreading system in accordance with the invention can also be applied versatilely to the spreading of different kinds of wet masses, and not just to an asphalt mass.

Other advantageous forms of application of the invention are described in connection with the example of performance presented later.

In what follows the invention is illustrated by reference to the accompanying figures, which shown one example of performance of the invention.

Figure 1 shows the principal machines of a mass spreading system in accordance with the invention. Figure 2 shows a mass-spreading machine seen from the rear.

The mass spreading system in accordance with the machine consists of a spreading vehicle 1 and one or more transportation vehicles 10. These transportation vehicles can be realized for example in accordance with publications WO 90/08021, EP 240594, and DE-0- 2,263,088. The transportation vehicles 10 can discharge their loads in a known manner by pushing their conical points into the feed opening of the truncated conical end 11 of the tank 2 of the spreader vehicle 1 and by rotating the tank, when the spiral inside it pushes the mass out. The vehicles include control members 8, 9 to centre the cones.

The spreader vehicle 1 consists of a chassis 5 carried on wheels

6, and a motor and control devices to move it. A rotatable tank 2 is attached to top of the chassis 5 by means of bearing rings

4. Spreader 3, which is also connected over its entire length to the rotating tank 2, is attached to the rear of the chassis

5. The support of the chassis 5 from the wheels 6 is arranged by means of an adjustable air spring 7, by means of which the spreading height can be adjusted.

Because when the asphalt mass cools its adheres to the inner surface of the tank 2, this is avoided by equipping the whole tank with heat-resistant heat insulation to prevent the cooling,

and with heating devices to heat the surfaces and loosen the bitumen from it.

The advantageous net capacity of the tank 2 of the spreader vehicle 1 is 20 tonnes. This is considerably greater than the capacities of the silos of known spreaders, in which case considerably heavier transportation equipment can be used. This in turn makes possible quite long transportation trips, when the asphalt station can be far away. The net capacity of the trailer shown in Figure 1 can be e.g. 34 tonnes, when the maximum amounts of present asphalt loads are 13 tonnes.

Because the asphalt mass is not in contact with the open at¬ mosphere during transport or work, the danger of oxidation is smaller than before. In addition, the openings of the tanks can be closed with suitable covers if required. Work is also possible during rain, because rainwater does not get into the tank. The conical end 11 can be fitted with a funnel section by means of a joint permitting rotation, when other kinds of transportation vehicles than that shown in Figure 1 can be used for the feed. A funnel of this kind is, as such, known from the aforementioned publications.

It should in particular be noted that the transfer spiral inside the transportation tanks continually mixes the mass, and grading does not take place. The feed channel of the screw in the spreader vehicle fills continually by gravity with new homogenous mass, and thus avoids grading at this stage. The system can also be used to spread a pavement on a road-bed.

It is easy to clean the tank and spread section of a spreader vehicle in accordance with the invention, because the washing liquid is able to circulate freely over all the tank surfaces, directed by the spiral, and a large maintenance hatch can be arranged in the spreader section, from which it is easy to gain access to the moving parts.