I gather they do normally have springs...

Apparently one of the significant 'safety' features of this style of vehicle, besides being enclosed all the way round and having an hinged door in the back of the body, is that it has a dropped 'crank' axle, so that you can have high wheels (for comfort on a rough road -- you go over the top of the holes rather than dropping down into each and every one of them) combined with a low centre of gravity. Unlike more sporting vehicles they were supposed to be very difficult to overturn!