also, i was just thinking about how the air brakes worked on my dad's old oil delivery trucks, as well as with the busses that i drive now. they apply the parking break which is air operated and it keeps pressure even with the vehicle turned off. if they make a mechanical style line lock for hydraulics, then i'd say that would work fine for a parking brake. again i don't know how the electric style work, so that might work fine too
someone enlighten me, as i don't have time right now to search the difference