A pneumatic system with multiple air reservoirs (22,24,26) is connected to the bellows (18) of a load elevator (10). A plurality of valves (28,30) enables the optional pneumatic connection of different combinations of reservoirs so as to change the range of operation of the elevator to meet the self-adjusting weight requirements of a particular job at hand. In the preferred embodiment, the air actuator (18) is pneumatically connected to a main air reservoir (22), which in turn can optionally be coupled in series with one or two additional reservoirs (24,26) of different capacities. As a result of this configuration of its pneumatic system, the elevator (10) can be switched between and operated at three different load levels, at the convenience of the operator, without changing the amount of air in the system.