How about the airport trolley?
The luggage in the car, the cart is braking, pushed very hard, need to press the rower, normal, push up.
A cart down, can be pushed away, the cart can only push to security, such as hand luggage into the cart and security needs.
The airport is called baggage car, usually 3 wheels, when the handle down, release the brake. Enter security cannot cart (in the lounge there are carts, but generally have large luggage checked, so there is no need for the hand cart cart), downward pressure, not loose, loose natural implementation can; drove the bus stopped, the brake function.
