theoretically hydraulics can be regenerative. Whilst lowering a heavy load to the ground, the pump is being 'sucked', and the engine could be consuming no fu

theoretically hydraulics can be regenerative. Whilst lowering a heavy load to the ground, the pump is being 'sucked', and the engine could be consuming no fuel during such an operation. Practically they rarely are, because the way a piston is moved 'slowly' is to have a half-open valve with a pressure drop across it, and that half open valve wastes all the energy into heat in the fluid.