cylinder head four-valve mechanism Roof-shaped combustion chamber with four-valve mechanism. Distribution of the ducts for discharge and intake valves. By turning the camshaft the opening and closing of the valves can be demonstrated. description ordernumber 1230 see also: feed pump, diesel (single-acting) pump with slide-valve control (electronically controlled) Injection timing device, in-line pump turbo-charger with variable geometry and electrical control motor