Rechamus.
Vitruvius (De Architectura 10.2): Alligatur in summo trochlea, quem etiam nonnulli rechamum dicunt. The pulley block, which some also call rechamus, is fastened at the top. This mysterious word rechamus appears to be very rare, and I would quite like to know its etymon. [For trochlea.]
Also tagged rechamus, translation, trochlea, Vitruvius