[Mark McLeod]

Yea, I take back what I said about Maxi, they do look like a fit.
They match the dimensions of the 40a slot in the PDB.
I was mixing them up with the ATO fuses.

P.S.
Found supporting evidence in a snap action 40a breaker spec sheet quote
"Direct replacement for "MAXI" automotive style fuses"

So the question becomes how close to the 40a fuse maximum does your non-FRC robot run?
If it draws less than no problem. If it regularly draws over 40a, in a starting stall condition for instance, then it'll be a question of how often do they need replacement before the $6 breaker would be the better bargain.