Patent claim: In a machine for painting dyeing or impregnating processes a device for cleaning the lower return section T of a conveyor belt T driven on rollers R from fluid substances sprayed onto it said device being of the type which comprises at least one reverse roller C1 rotating in a direction F opposed to the sliding direction F of the lower section T of the belt T said roller C1 being in contact along a tangent line A with the lower section T of the conveyor belt T to be cleaned so as to scrape it characterized in that at least one first doctor blade 7 for scraping the lower section T of the conveyor belt said doctor blade being arranged to form between the lower section T of the conveyor belt T and the reverse roller C1 a space V conduit means 1 for introducing a cleaning solvent into the space V means 107 for limiting the immediate discharging of the solvent from the space V so that the reverse roller C1 is wetted by the solvent over its entire axial length and further comprising at least one hopper 2 for collecting the solvent exiting from the sides of the space V.

Related passage: Immediately downstream from the preliminary cleaning cylinder 1 there is a vessel 7 provided with a Ushaped front edge 107 which is made from such material and shaped in such a way that it interacts in a sealed way with the lateral surface of the cylinder 1 and which is kept in contact with this cylinder by suitable means the said vessel 7 being provided with lateral and transverse containing walls 207 307 which are integral with each other and with the said sealing edge 107 and having a height such that they are as close as possible to the branch T2 of T so that the vessel 7 in question is essentially closed by the conveyor T.A scraper blade 8 of suitable material is provided on the upper edge of the transverse wall 307 of the vessel 7 and is pressed by suitable means against the branch T2 to be cleaned which is controlled if necessary by opposing rollers 4 of a known type.Solvent 9 is made to flow into the vessel 7 and is kept at a predetermined level the said vessel being provided for this purpose in its opposite lateral walls 207 with corresponding holes 10 one of which is connected to solvent delivery means while the opposite hole is connected to a discharge channel.By rotating in contact with the solvent in the vessel 7 the cylinder 1 transfers a film of this solvent to the branch T2 to soften any residues of paint which are then removed by the scraper blade 8 and fall into theflow of solvent 9 by which they are removed.Clearly the described solution resolves one of the problems of the known art since the solvent vessel 7 the cylinder 1 and the portion of belt T2 in contact with the solvent are form an enclosure for each other to limit the evaporation of the said solvent.To prevent the dispersion of any leaks of product from the sealing edge 107 of the vessel 7 and therefore to enable the device to be made without highly precise tolerances an auxiliary trough 11 can be arranged under the vessel 7 so that the edges of its walls can interact in contact with the vessel 7 and close to or in contact with the cylinder 1 but without touching this cylinder at least with its front transverse edge 111 to limit the amount of exposure of its internal parts to the air.The trough 11 can usefully be utilized as a channel for the return of the solvent discharged from the vessel 7 replacing the channel which makes the return available on the same side of the device as that on which the solvent delivery means operate.Should any traces of paint tend to pass beyond the scraper blade 102 of the trough 2 they would be recovered by the scraping carried out by the edge 107 on the cylinder 1 and would fall into the auxiliary trough 11.