The membrane pumps are designed with B+L's patented membrane positioning system (PDPC), which effectively prevents membrane fractures even in extreme operating conditions. The pumps are lineic and the capacity changes via the stroke length. The regulation can be done both manually, as well as electrically or pneumatically. In the case of multi-head pumps (up to 6 elements on the same drive motor), adjustment can be done individually on the various elements, both during walking and at standstill.