English to Portuguese Tech/Engineering Electronics / Elect Eng métodos de ensaio

These quieting ramps are flat spots in the contour which occur at 0.008 in. to 0.010 in. rise from the base circle of the lobe and that extend for typically 4° to 6° of crank angle rotation.
Actual valve lift does not take place until valve clearance is overcome and this is essentially coincident with the flat spot of the quieting ramp.
The maximum height of the lobe from the base circle is typically 0.248 in.
A2.1.1  Measurement Principle—It is difficult to define the actual point at which a valve should open or close because the event takes place on the quieting ramp where the rate-of-change of the cam profile is minimal