English to French Tech/Engineering Engineering (general)

device for the processing of plant stems containing cellulose fibres
Between the top rollers there is placed a stripper slate whose bottom part is shaped into radius and its sides are flat. The stripping slate is fixed to the *lead* of the upper roller which is hinged to and it is as well as the top roller vertically movable.

que peut signifier "lead" dans ce contexte ?
merci d'avance