---the unit has to get towed to the shop.
Preventative maintenance prevents most catastrophic failures. If a failure does occur, we try to catch it early and limp it to the shop under it's own power. Sometimes, stuff happens and the tow company smiles.
When it does happen, my boss and the maintenance chief don't smile. That's $400 or so that the district could use for something else.
As long as it isn't your rig, there is some giggle value involved. One can always bust somebody's chops when that somebody's rig is on a flatbed or a hook. In this age of camera phones, the event almost always gets documented for a chop-busting at a later date.
Of course, since I always have a camera with me, I don't have to use my phone.
Thanks for reading,