TECHNICAL FIELD The present invention concerns a device at cas¬ settes for spring members for a machine e.g. a sweeping machine, which in one embodiment can be proposed i.a. for removing of rubber rests, snow and ice from runways for aircrafts, at which spring members are manufactured of steel, and which in another embodiment can be proposed for removing snow from railway tracks and switches, at which the spring members are manufactured of plastic. Thus the device is usable at sweeping machines for seve- ral different purposes. The cassettes are arranged around the periphery of a rotatable roller and extending mainly in the longitudinal direction of the roller and including units of spring members, as radially extending bristles, which ends are brought in contact with the ground, e.g. a runway, at the rotation of the roller. Each cassette in- eludes a longish bar, which is arranged in facing grooves in brackets which extend along the length of the roller. BACKGROUND TECHNICS

A great number of solutions are known for faste¬ ning of cassettes for bristle bunches arranged around the periphery of a bristle roller, which in its turn is ro- tatably mounted on a sweeping machine or the similar. The Swedish patent publication SE-B-421 331 describes a bristle roller which shows longish cassettes in which bunches of bristles are arranged in openings along the length of each cassette. Each cassette is accomodated in grooves extending along the length of the bristle roller and is constituted by two facing U-shaped sheet profiles, which show facing openings, in which bristle bunches are arranged with radially projecting bristles. The sheet profile in the cassette by its weight here constitutes a disadvantage as the cassette is exposed to big mass for¬ ces at the rotation of the bristle roller.

Another embodiment of a bristle roller is known by the American patent publication US 4,538,319. A cas¬ sette similar to the one which is described in the patent publication 5E-B-421 331 here is arranged between brac- kets which in its turn are attached to a longish roller. The brackets show grooves for sliding lists, which in its turn show sliding grooves in which the cassettes are ac¬ commodated. The sheet profiles in the cassette also here make a disadvantage as their weight make them awkward and giving rise to non desirable mass forces at the rotation of the bristle roller. The present invention i.a. consti¬ tutes an improvement of the device according to US 4,538,319 and is described below. DESCRIPTION OF THE INVENTION The purpose with the present invention is to achieve a device according to the preamble above, which constitutes an improvement of a cassette for spring mem¬ bers which is possible to use at a bristle roller similar to the one described in the patent publication US 4,538,319- The device includes a rotatable roller carrying brackets for the cassettes including units of spring members. Each cassette includes a longish, ela- stically and/or plastically deformable bar, which is arranged in facing grooves in the brackets extending along the length of the roller.

The invention is characterized in that each spring member is kept together by means of a resistant ring-shaped member, which surrounds a portion of each spring member being depressed into the bar. The depressed portion of each spring member can be surrounded by an elastic cage outside which the ring-shaped member is arranged. The ring-shaped member also can be arranged inside said socket or constitute an integrated portion of the same. By the ring-shaped member each spring member is kept together discharging the surrounding bar from radial forces from the bristles in the spring member. By that

these forces are prevented from transmitting to the bar and deforming the same at each member. Such deformations otherwise can be permanent and complicate demounting of the bristle cassettes from the roller when these are to be exchanged e.g. when weared out. The ring-shaped member also facilitates the mounting of bristle cassettes in the bar mentioned above in that each bristle cassette by this member is given an exact diameter corresponding to the diameter of the holes in the bar. The varying characte- ristics of the spring members, e.g. regarding radial for¬ ces which arise at the assembly of the elements, are eliminated also by the ring-shaped member.

As the device, which is described in the patent publication US 4,538,319, the brackets for the cassettes preferably are provided with sliding bars, showing grooves in which the cassettes are accomodated. In the device according to present invention each cassette also shows a bar of plastic, which partly makes the manufac¬ turing of each cassette cheaper, partly facilitates the insertion respectively removal of each cassette at ex¬ change. By the invention preferably is avoided a deforma¬ tion of the plastic bar by the inner forces in the spring members mentioned above.

Further characteristics of the invention will be clear from the description to drawings below and the en¬ closed claims. DESCRIPTION TO DRAWINGS

The invention is described below as an embodi¬ ment according to the enclosed drawings. Figure 1 fragmentary shows a rotor with casset¬ tes carrying spring members in a cross section to the longitudinal direction of the rotor.

Figure 2 shows a part of a cassette with spring members mounted in brackets extending along the length of the rotor.

Figure 3 shows a sliding list to each bracket in a cross section.

Figure 4 shows a part of a spring member enlarged.

Figure 5 shows a mounting of spring members in a part of a cassette. Figure 6 shows a cross section through the cas¬ sette with spring members along the line A-A in figure 5.

Figure 7 separately shows a secion of a bar to the cassette according to figure 5 and 6.

Figure 8 shows an alternative embodiment of brackets for spring members.

Figure 9 shows a cross section of the brackets along the line B-B in figure 8.

A rotor for e.g. a sweeping machine comprises a cylinder-shaped, longish roller 1 which carries brackets 2 for longish cassettes 3 with spring members 4 extending along the length of the roller 1 and are arranged close to each other along the periphery of the roller 1. Two adjacent brackets 2 is shown in figure 1 and enlarged in figure 2. The brackets 2 are kept to the roller 1 by means of wedge members 5 which are situated between each bracket 2 and equally spread along the length of the rol¬ ler 1. These bracket 2 and belonging wedge members 5 are known earlier from the patent publication US 4,538,319 which is mentioned above. The brackets 2 show grooves 6 on each side, extending along the full length of each bracket 2, in which sliding lists 7 of plastic are arranged. The sliding lists 7 show facing rectangular sliding grooves 8 in which a cassette 3 is accomodated and thereby filling up the space between two brackets 2. A gap 8.1 is arranged between each sliding bar 7 and the intermediate cassette 3.

Each cassette 3 includes a bar 9 of plastic, which shows mainly cylinder-shaped, cup-shaped means (cups) 10 equally spread along the length of the bar 9. The cups 10 in its turn carries sections of mutually connected cages 11, which are brought into the cups 10 and in which spring members 4 are collected in a way

making their free ends projecting from each cage 11. The number of projecting spring members 4 in each cage 11 is 100 - 400 and has a diameter of 0,1 - 2,0 mm, particular¬ ly 0,3 -1,0 mm. Each spring member 4 is constituted by a steel wire showing a characteristic diameter (d), waves with a wavelength (1) and a waveheight (h) as shown in figur 4 and with the following dimensiones: 1 = (2 to 20) x d, particularly max 5 x d, h = +. (1,5 to 3) x d. A bar 9 to a cassette 3 is shown in a section in figure 5 and in a cross section in figure 6. The bar 9 which is shown in the figures shows a mainly rectangular downwards open cross section. The cups 10 are arranged projecting down from the upper side of the bar 9 and are provided with a bottom 10.1. Between the cups 10 two mu¬ tually parallel supporting walls 10.2 extend, which part¬ ly serve as a stiffener of the bar 9, partly constitute a guide for a locking wire 10.3 which at mounting of the cages is brought through holes in facing sides of the cups 10 and through cages 11 with spring members 4 which are brought down into the cups 10. Further the cages 11 are provided with uppwards projecting basket-like means (baskets) 12, which in its turn are mutually connected with a connecting wall 13- The bar 9 with the cups 10 and the cages 11 with spring members 4 attached therein is known earlier as well as the device to lock the parts together to a cassette 3«

The cages 11 shown in figure 5 and 6 further are provided with ring-shaped members, here called dischar- ging rings 14, projecting down into the openings at each cup 10 in the bar 9. The discharging rings 14 are keeping the spring members 4 together and discharges the cages 11 from radial forces from the bristles in the spring mem¬ bers 4. By each discharging ring 14 these radial forces are prevented from being transmitted to the bar 9 and deforming the same at each spring member 4. The dischar¬ ging rings 14 in this embodiment also can be mutually

connected in groups or along the full length of the bar 9. In the case in which the discharging rings are collec¬ ted in sets each such set is corresponded by a set of cages 11 and baskets 12 for the same number of spring members 4.

In an alternative embodiment of the invention, shown in figure 8 and 9, the discharging rings 14 are arranged inside each cage 11 directly contacting the spring members 4. In this embodiment the cages 11 also are completely discharged from radial forces from the spring members 4.

The embodiments of the invention described give a very solid cassette which is easy to exchange as it does not show said deformations at the spring members 4 and which permits high rotation speed of the roller in use. A roller of a diameter of 300 mm can be given a rotation speed of 600 - 1000 r/min, which corresponds to a periphery speed of about 600 - 1000 m/min.