In internal combustion engines with pistons, the camshaft is used to operate poppet valves. It consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes protruding from it, one for each valve. The cam lobes force the valves open by pressing on the valve, or on some intermediate mechanism, as they rotate.
what does a camshaft do for your car
used to operate poppet valves