Kaushitakagrihyasutra 2.8.3

2.8.3

atha ceda daṇḍamekhalopavītānāmanyatamadviśīryeta cchidyeta vā tasya tatprāyaścittiḥ yadudvāhe rathasya \3\

Now if any of the staff, the girdle, or the sacred thread should break or be cut, its expiation is the same as that for the chariot at marriage.