The latest Flottmann engine, which is fixed directly to the conveyor trough, differs materially from the foregoing, but is, strictly speaking, a single-acting engine. Figs. 227 to 229 give a good idea of the details of the working parts. The cylinder is open at both ends, and in it move two pistons connected by rods to the junction of two pairs of toggle levers. The illustration represents the two pistons at the beginning of their cycle of movements, that is, close together and with the port for the admission of compressed air open; the pistons are now forced apart, and with them the toggle levers.