Pressure roll for a tire building apparatus for preparing pneumatic tire blanks with a building drum for receiving tire layers. The pressure roll cooperates with the building drum has a plurality of discs mutually slidable with respect to one another and on a shaft so as to extend radially with respect to the building drum, the discs being mutually uniformly shaped, and each disc having an interior part and an exterior ring surrounding the interior part and being rotatable about a ball bearing, the interior part having a recess whose sidewalls slide radially on the sidewalls of the shaft and whose length is greater than the corresponding size of the shaft. The shaft extends in the longitudinal direction of the pressure roll. The shaft is provided with a number of radially directed bores equal to the plurality of discs, and in each bore a piston is disposed that engages the interior part of the respective disc concerned. The shaft is provided with pressure medium channels for feeding a pressure medium to a bore.
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