in the arrangement reproduced in fig1 a material web 1 is guided from an initial roll 2 over a deflection roller 3a to a web guide roll 4 which centers the material web 1 and is supplied with a certain mechanical pre - tension t over a further deflection roll 3b to a roll arrangement 5 , 15 where the material web is subject to a press processing . in addition to the material web 1 , a dewatering felt 18 is also fed through the press gap which is formed by a press roll 15 in accordance with the invention and a hard roll 5 , for instance a granite roll . on weight grounds , the press guide roll 15 and the web guide roll 4 are made from a light roll tube 20 and 6 respectively rotatable about an axis 19 and a respectively , the roll tube being made of , for instance , plastic or light metal . this roll tube 20 and 6 is advantageously wound layer - wise from glass - fiber - reinforced or carbon - fiber - reinforced artificial resin which provides adequate strength even for thin wall thicknesses . in order to protect the relatively soft surface of the plastic guide tube 20 and 6 from too rapid abrasion and wear , a layer 7 made of a material with better strength than the roll tube 20 and 6 is wound around the outer surface of the roll tube 20 and 6 respectively , with advantage from a wire or belt made from a suitable metal , for instance steel , or also from a fiber - reinforced plastic see fig4 n . a single wire or belt winding is , as a rule , sufficient to achieve an improved resistance to abrasion , however a plurality of wire or belt layers can also be wound ontop of one another . in the example of fig2 the wire winding 7 is almost peripherally oriented . here , the wire winding 7 can extend in the axial direction over the entire surface of the roll tube 20 or 6 , in particular for use as a press roll , or can be provided for certain applications only over a part of the outer surface of the roll tube 6 , i . e . gaps 16 may be present between the individual parts of the winding . in many cases an adequate axial guidance of the material web 1 can be achieved for web guide rolls 4 having a peripherally oriented winding 7 and grooves 17 so that further lateral divergence can be prevented without having to provide positional measurement devices for the web edges . it is however of especial advantage to orientate the wire or belt winding 7 over the surface of the roll tube 6 in such a way that the material web is automatically centered , i . e . is automatically guided back to the middle when lateral divergence occurs . in the example shown in fig3 this is achieved in that , although the middle part 7a of the wire winding is oriented peripherally , the windings 7b and 7c on both sides of the middle m are inclined at an acute angle relative to the peripheral direction and moreover in an opposite sense on the one side 7b to on the other side 7c . the winding as a whole is thus constructed mirror symmetrically with reference to the mid - plane m of the roll tube . in this manner , a guiding back of the material web to the roll middle can be achieved as soon as it tries to break out sideways along the axial direction . the cross - section of the material to be wound on can be chosen differently and be tailored to the material web to be transported by the web guide roll . fig4 shows various suitable variants wherein the press rolls 15 preferably have smooth surfaces in order to form a cylindrical roll shape with grooves . in accordance with fig4 a , a wire layer 7 of metal wire of circular cross - section is wound onto the roll tube 6 . flutes 17 are thereby formed between the neighboring wire windings . in accordance with fig4 b , the wire winding 7 is embedded somewhat into the soft surface of the roll tube 6 which is not quite set . here , it is advantageous to condition the surface of the wire prior to embedding to achieve an improved grip between the wire windings 7 and the wire tube 6 . the outer surface of the wire winding 7 is ground and / or polished so that a smoother surface is formed than in the previous example but wherein , however , grooves 17 are still present between the neighboring windings . in accordance with fig4 c and d , the cross - section of the wire 7 can also be constructed to be rectangular or quadratic , whereby various surface profiles can be achieved depending on the specific requirements . various trapezoidal , triangular , oval , elliptical or irregular cross - sections of the wire , such as those shown in fig4 e to 4k , can be of advantage , depending on the conditions and the web material to be transported . instead of wire , suitable belt - shaped material can be used for the production of the winding . as is shown in fig4 l , the wound - on belt 7 can also be wavy , whereby wave - shaped grooves 14 running in the peripheral direction are formed on the surface . as is shown in fig4 m , neighboring belt windings 7 can overlap in the manner of roofing tiles which protects the surface of the roll tube 6 especially well from abrasive and corrosive influences . the mechanical strength and durability and the resistance to corrosion of the material used for the wound - on wire or belt 7 should be chosen with regard to both the press forces and the material web 1 to be transported . generally speaking , steel , optionally with special alloy additives , is adequate , however , in particular cases , the use of hard metal or glass - metal is of advantage , for instance in accordance with u . s . pat . no . 4 , 721 , 154 . in a simple embodiment , the roll tube 6 of the web guide roll can be provided with side cover plates 8 which carry the roll spigots 9 . the roll tube 6 rotates here together with the cover plates 8 and the spigots 9 . in order to produce an individually controllable mechanical pre - tension or an adequate press force in the transported material web 1 over the width of the roll , it is however of advantage to implement the roll tube 20 and 6 so as to be rotatable about a non - rotatable carrier 19 and 13 respectively and to displaceably support the roll tube 20 and 6 relative to this carrier 19 and 13 respectively with a row of supporting elements 10 arranged next to one another in the axial direction and having adjustable supporting force in the supporting direction t . a virtually friction - free running of the roll tube 20 and 6 can be achieved with hydrostatic supporting elements 10 which run on the smooth inner surface of the roll tube 20 and 6 respectively by means of hydrostatic bearing surfaces 11 and are supported displaceably in the support direction relative to the carrier 19 and 13 respectively which contain a pressure volume 12 which is supplied with a liquid or gaseous pressure fluid and is of controllable or regulatable pressure and which enables a controllable or regulatable supporting force of the supporting elements 10 to be produced relative to the roll tube 20 and 6 respectively .