Understanding the Cam Profile Terms.

The parts of a camshaft lobe that actually initiate the lifting and descending movement of the lifter are called "ramps". Ramps include the lash ramp, the opening ramp, and the closing ramp. Camshaft lobe ramps are ground to have different rates of lifter movement in terms of velocity and degrees of duration, as measured in degrees of crankshaft rotation.

The "lash ramp" of a camshaft lobe is a mid-point location between the opening ramp and closing ramp.

The "opening ramp" of a camshaft lobe is the point where the lifter just begins to lift until the point that it reaches the nose of the lobe.

The "closing ramp" is the point of the camshaft lobe from the nose back down to the lash ramp. 

 

NOSE The "nose" of a camshaft lobe is the top or the highest maximum lift point for the valve. It is where valves are kept open for as long as possible before making the transition to the closing ramp.