Rolling the car backwards was an inadvertently interesting comment to me. A Story I called the system design she-brakes. Back in the 'big block shooting brake' days when rich America was in the middle of a roads and housing boom new towns just off motorways were built with big wide boulevard's and the roads were deliberately sunk low so drives were up a slope to allow drainage from the property. There was a rash of insurance claims made for 2 1/2 ton cars rolling unattended backwards into traffic so the 'top hat' shoe was redesigned to grab the trailing rather than the leading edge - after all it's a parking brake design not a handbreak. This still exists as far as I'm aware to this day.