Cam apparatus for use with valves

An apparatus comprising:

• a valve body defining a chamber and a gland;
• a stem extending into the chamber of the valve body;
• a shaft disposed in the gland of the valve body such that a seal is formed between the shaft and the gland, the shaft having an end that extends into the chamber of the valve body adjacent the stem;
• and
• a cam coupled to the end of the shaft and defining an outer surface to engage an end of the stem, the outer surface having a first portion to engage the end of the stem in a closed position, a second portion to engage the end of the stem in an open position, a third portion adjacent the first portion and defining a curved profile that is to engage the end of the stem in a first intermediate position, and a fourth portion between the second portion and the third portion and defining a linear profile that is to engage the end of the stem in a second intermediate position.

An apparatus comprising:

• means for transforming rotary motion to linear motion;
• means to engage a stem in a closed position defined by the means for transforming;
• means to engage the stem in an open position defined by the means for transforming;
• means to engage the stem in a first intermediate position as the means for transforming rotates between the closed position and the open position, the means to engage the stem in the first intermediate position defining a curved profile and being adjacent the means to engage the stem in the closed position;
• and
• means to engage the stem in a second intermediate position as the means for transforming rotates between the first intermediate position and the open position, the means to engage the stem in the second intermediate position defining a linear profile and being positioned between the means to engage the stem in the open position and the means to engage the stem in the closed position.