A treatment apparatus for treating receptacles, in particular bottles comprising: - a carousel conveyor adapted to rotate around a central axis to advance the receptacles along a predetermined path; - a plurality of support units arranged on the carousel conveyor at a peripheral portion of said carousel conveyor; wherein each support unit is equipped with a pedestal adapted to support a respective receptacle during advancement of the respective receptacle along the aforesaid path and a support bar carrying the respective pedestal; wherein each support unit further comprises a support housing, in particular a hollow cylinder, having an inner channel, said channel extending parallel to the aforesaid central axis; wherein each support bar is housed in the respective channel and is adapted to slide in the respective channel in a respective predetermined linear direction; and wherein each support unit comprises a locking 2 assembly (40, 40') adapted to interact with the respective support bar and the respective channel and being controllable in at least a locking configuration and in at least a release configuration to respectively lock or release the support bar and respectively prevent or allow sliding of the support bar in the respective channel, wherein each locking assembly is arranged coaxially to the respective support bar and to the respective channel, wherein each interaction portion is interposed between the respective channel and the respective support bar, wherein each locking assembly comprises at least one interaction portion, which partially surrounds at least the respective support bar, characterized in that each locking assembly comprises a control element (47, 55) adapted to carry out an expansion or contraction in a radial direction of the respective interaction portion to respectively lock or release the respective support bar, characterized in that each interaction portion comprises an inner cavity having a ring shaped cross section containing a hydraulic liquid; and wherein the related control element is adapted to control a pressure acting on the hydraulic liquid to expand or contract the respective interaction portion. - a carousel conveyor adapted to rotate around a central axis to advance the receptacles along a predetermined path; - a plurality of support units arranged on the carousel conveyor at a peripheral portion of said carousel conveyor; wherein each support unit is equipped with a pedestal adapted to support a respective receptacle during advancement of the respective receptacle along the aforesaid path and a support bar carrying the respective pedestal; wherein each support unit further comprises a support housing, in particular a hollow cylinder, having an inner channel, said channel extending parallel to the aforesaid central axis; wherein each support bar is housed in the respective channel and is adapted to slide in the respective channel in a respective predetermined linear direction; and wherein each support unit comprises a locking 2 assembly (40, 40') adapted to interact with the respective support bar and the respective channel and being controllable in at least a locking configuration and in at least a release configuration to respectively lock or release the support bar and respectively prevent or allow sliding of the support bar in the respective channel, wherein each locking assembly is arranged coaxially to the respective support bar and to the respective channel, wherein each interaction portion is interposed between the respective channel and the respective support bar, wherein each locking assembly comprises at least one interaction portion, which partially surrounds at least the respective support bar, characterized in that each locking assembly comprises a control element (47, 55) adapted to carry out an expansion or contraction in a radial direction of the respective interaction portion to respectively lock or release the respective support bar, characterized in that each interaction portion comprises an inner cavity having a ring shaped cross section containing a hydraulic liquid; and wherein the related control element is adapted to control a pressure acting on the hydraulic liquid to expand or contract the respective interaction portion.