The use of polyarylene sulfides or liquid-crystalline polyesters is described in cooling devices for electrical equipment. After the fuel has been ignited and during the compression of such mixture a quantity of water from a reservoir is injected into the combustion chamber and converted by the heat of combustion into superheated steam, thereby generating within the combustion chamber a force which assists in driving the piston through its power stroke. The actuation portion is adapted to rotate the lever about said pivot between a first orientation in which the engaging portion retains the engaged portion and a second orientation in which the engaging portion does not retain said engaged portion. The hoisting platform is positionable along the platform leg.