Provided are methods for automatically positioning ramps in a station for the heating of preforms. The method includes acquiring an image of a preform traveling along a slot delimited by a pair of ramps, where at least one of the ramps is transversely mobile to vary the width of the slot (56) and where a motorized device transversely moves the at least one mobile ramp and is controlled automatically by an electronic control unit. The method further includes automatically determining the diameter below the neck of the preform by computer processing the image and automatically adjusting the width of the slot by moving the at least one mobile ramp according to the determined diameter below the neck.

An apparatus for heating plastic preforms includes a first transport device that transports the plastic preforms in a separated manner, wherein said first transport device has a plurality of recesses for receiving the plastic preforms, and a second transport device that takes over the plastic preforms transported by the first transport device and transports said plastic preforms along a predetermined transport path. The second transport device has a plurality of holding elements for holding the plastic preforms. The apparatus also includes at least one heating device that heats the plastic preforms transported by the second transport device, wherein at least the first transport device is a circulating transport device, wherein a relative position of the recesses of the first transport device in the circulation direction of the first transport device relative to a position of the holding elements in respect of the transport path can be changed.

An apparatus for heating plastic preforms includes a first transport device that transports the plastic preforms in a separated manner, wherein said first transport device has a plurality of recesses for receiving the plastic preforms, and a second transport device that takes over the plastic preforms transported by the first transport device and transports the plastic preforms along a predetermined transport path. The apparatus has at least one sensor device that detects at least one measured value that is characteristic of at least one of the two drive devices, and a control device that is designed to control the drive device for moving the holding elements as a function of this characteristic measured value.