A special piston/valve system is used to isolate the two pressure chambers in the spring, enabling effortless variable locking. If the tappet is released from the outside, the exchange between the pressure chambers is interrupted and the air spring locks, holding the load reliably in place, even for heavy loads. When the valve is opened, the linear spring characteristic curve of the BLOC-O-LIFT locking air spring provides a balanced increase in force over the entire range of motion.