Known compactors are used especially on landfill sites, to effectively crush and compact garbage. For this purpose, the compactors are heavy, their wheels being rollers equipped with spikes. Due to their large masses and slow speeds, hydrostatic transmissions are preferably used in these compactors. To rationalize the manufacture of compactors of varying power, their transmissions are assembled from a single type of module, the number of modules varying according to the power required.

Such a compactor series including a compactor is known from US patent publication 4,854,772. In it, there is a diesel engine, which continues in a transfer gearbox, to which from one to four hydraulic pumps are connected as required. The hydraulic pumps rotate the rollers'hydraulic motor units. In the largest compactor of the compactor series, there are hydraulic motor units at both ends of both rollers. Thus, each roller end has its own hydraulic pump, when all four hydraulic pumps are used.

Generally, one hydraulic pump is thus required for each motorized end part of a roller.

Despite the modular construction, this compactor transmission is disadvantageous. The transfer gearbox used in each compactor

must be dimensioned according to the largest compactor. Thus, the transfer gearbox is clearly over-dimensioned in all except the largest compactors. In addition, the transfer gearbox itself is an expensive and complex component, which requires a great deal of maintenance. However, from the point of view of driving the compactor, the difficulty of controlling the roller hydraulic motor units is even more significant, in situations in which there are hydraulic motor units at both ends of the roller. Despite highly-developed hydraulic motors and their control technology, there are always differences in the rotation speeds and moments of hydraulic motor units rotated by two different hydraulic pumps. In practice, the hydraulic motors at one end of the roller brake the rotation of the roller. This increases the compactor's energy consumption and strains the transmission. In addition, full pressure and return lines must be made from each hydraulic pump.

The invention is intended to create a compactor and compactor series, the compactors of which have simpler transmissions and are more easily steered than previously. The characteristic features of the present invention appear in the accompanying Claims. By means of suitable transmission connections and components, it is possible to manage with the smallest possible number of hydraulic pumps. At the same time, a separate transfer gearbox is not needed at all. In addition, the control of the hydraulic motor units is simpler than previously and no braking effect appears. A construction solution according to the invention also leads to saving in the amount of hydraulic piping.

In the following, the invention is disclosed in detail, with reference to the accompanying drawings showing some embodiments of the invention, in which Figure la shows a simplified side view of a compactor according to the invention,

Figures lb-2b show simplified top views of a compactor series according to the invention.

Figure la shows a simplified side view of a compactor according to the invention. The compactor includes a chassis-steered base and rollers 11 and 11'arranged in both of its chassis sections 10 and 10'. There are spinous protrusions 12 in rollers 11 and 11', which improve the crushing and compacting power of the compactor. In addition, essentially identical hydraulic motor units are arranged in connection with rollers 11 and 11'. The hydraulic motor units, more briefly referred to as the units, are located in the end parts 14 of rollers 11 and 11'. However, the figures do not show the individual hydraulic motors. In the front chassis section 10 there is a driving cab 15 and in the rear chassis section 10'there is an engine 16 with its auxiliary equipment and fuel tanks. In addition, hydraulic pumps are connected to engine 16 and are connected by suitable pipelines to the hydraulic motor units arranged to rotate rollers 11 and 11', in order to drive the compactor.

In a compactor according to the invention, there are two hydraulic pumps, which are arranged in tandem as a direct continuation of the engine. In this case, a separate transfer gearbox is not required, thus simplifying the construction of the transmission. In addition, each hydraulic pump is arranged to rotate the units of different rollers. Thus, a suitable hydraulic pump can be selected for the roller to suit individual cases. The selection of the hydraulic pump is described in greater detail in connection with Figures lb-2b.

Figure lb shows a compactor, with units 13 only in one end of its rollers 11 and 11'. In this case, both hydraulic pumps 17 are preferably identical and they each rotate a different roller. In the figures, the same reference numbers are used for components that are functionally similar. The number of units thus varies according to the size class of the compactor. In

the compactor of Figure lb, the oil pipes between the units 13 and the hydraulic pumps 17 are conventional.

Figure 2a shows a compactor that is larger than the previous one, and which has a rear roller 11'that is longer than the front roller. At the same time, the power requirement of the rear roller 11'increases, so that units 13 are placed in both end parts. The driving of an originally advantageously module- dimensioned compactor with the same units thus requires double the power. In this case, a hydraulic pump, which has double the power of the short roller's pump, is used for the long roller.

In other words, in the compactor in question, a large hydraulic pump 17 and a hydraulic pump 17 half of its size, are used in tandem as a continuation of the engine. Naturally, the engine's power must then also be greater. In addition, the units of the longer roller are connected in parallel to a correspondingly large hydraulic pump 17. Hydraulic oil, at a pressure and volume flow that are essentially the same, flows to the units at both ends of the long roller. In addition, the unified roller keeps the speed of the units always the same, so that it operates as a kind of differential lock. Thus, the units of the same roller always rotate at the same speed, without a braking effect. This makes the compactor easier to steer and reduces energy consumption. At the same time, the transmission pressure and return lines are shorter than in known solutions. In Figures lb-2b, the pressure pipes are only shown diagrammatically by broken lines.

In the compactor of Figure 2b, there are units 13, at both ends of both rollers 11 and 11', which are connected in parallel to a corresponding hydraulic pump. In this case, both hydraulic pumps 17 have thus a higher output. In the compactor in question, an even greater saving is achieved in the lengths of the piping, compared to the previous compactors, especially in the case of the front roller 11.

A compactor according to the invention allows the creation of a compactor series, which comprises at least a small, medium, and large compactor. Each compactor in the compactor series has always two hydraulic pumps. In addition, the hydraulic pumps are set in tandem directly as a continuation of the engine, so that a separate transfer gearbox is not required. Further, both hydraulic pumps are arranged to rotate the units of different rollers, which facilitates the steering of the rollers and the selection of the output of the hydraulic pumps. In practice, in the compactor series, from two to four essentially identical units are arranged in the end parts of the rollers. There is a single unit, according to Figure lb, in both rollers of the small compactor. Correspondingly, in the medium compactor, there is one unit in one of the rollers and two units in the other roller (Figure 2). There are two hydraulic motor units in both rollers of the large compactor, as shown in Figure 2b.

The hydraulic pumps are preferably of two different output classes. The output classes are arranged in such a way that the hydraulic pumps of the larger output class are arranged to feed two hydraulic motor units connected in parallel in the same roller. Correspondingly, the hydraulic pumps of the smaller output class are arranged to feed a single hydraulic motor unit of a single roller. The larger output class is preferably two times greater than the smaller output class. Thus, the outputs of the hydraulic pumps always correspond to the power requirements of the various compactors in the compactor series.

In addition, only two different sizes of hydraulic pump are needed in the entire compactor series, the combination of which provides the necessary output classes.