Cams and Followers Eccentric Cam Pear Cam Drop Cam A cam is a mechanism that converts rotary motion into reciprocating motion. There are 3 basic types of cam that you need to be able to recognise and you should know the specific type of reciprocating motion and common uses for them. Eccentric Cam Circular in shape with an off-centre axle. Gives simple harmonic motion (the follower is always moving at a constant speed) Used in fuel and water pumps or in sewing machines. Pear Cam Follower is stationary for a proportion of the rotation as the bottom of the cam is circular. This is a dwell period. The follower then rises up the lobe and down the other side. This type of cam is commonly found in car engines to control the opening and closing of the inlet and exhaust valves. Drop Cam The follower gradually rises up the profile of the cam and then drops quickly. Used on industrial press machines.

Followers The follower is the part of the mechanism which is in contact with the cam. There are different followers depending on the type of cam being used and the complexity of the profile. Knife follower Can accurately follow a complex cam profile but will wear very quickly Flat follower Relatively simple but can only follow simple concave profiles. High in friction Roller follower Low in friction but requires maintenance.

This video gives a brief overview of the manufacture of a racing car camshaft. How many processes can you recognise? What QC checks take place?