Commentary Par XXXI 124

Rhyme forces Dante into synecdoche, the part temo (yoke-beam, or chariot pole [i.e., that to which the horses are attached]) for the whole (chariot).  For other occurrences of this word (timone in modern Italian), see [Purg XXII 119]; [Purg XXXII 49], [Purg XXXII 140], [Purg XXXII 144]; [Par XIII 9].