Drive key for rotating equipment accommodating center line misalignment while minimizing hysteresis

A drive key for use in a rotary valve, the drive key comprising:

• a first square side surface;
• a second square side surface opposite the first square side surface;
• a first rectangular side surface extending from the first square side surface to the second square side surface;
• a second rectangular side surface extending from the first square side surface to the second square side surface;
• a third rectangular side surface located opposite the first rectangular side surface, the third rectangular side surface extending from the first square side surface to the second square side surface;
• and
• a fourth rectangular side surface located opposite the second rectangular side surface, the fourth rectangular side surface extending from the first square side surface to the second square side surface,
• wherein the drive key comprises a square prism, and
• wherein the drive key has a non-uniform thickness, and
• wherein a first thickness proximate a middle of the drive key is less than a second thickness proximate a first outer end of the drive key and a second outer end of the drive key.

A method of assembling a rotary valve, the comprising:

• obtaining a first ball valve comprising a first stem extending from a first proximal stem end to a first distal stem end outward from the first ball valve, the first stem comprising a first slotted opening extending from the first distal stem end into the first stem;
• obtaining a second ball valve comprising a second stem extending from a second proximal stem end to a second distal stem end outward from the second ball valve, the second stem comprising a second slotted opening extending from the second distal stem end into the second stem, wherein the second stem extends towards the first stem;
• and
• inserting a drive key into the first slotted opening and the second slotted opening, the drive key extending from the first slotted opening of the first ball valve to the second slotted opening of the second ball valve to operably connect the first ball valve to the second ball valve,
• wherein the drive key comprises a square prism,
• wherein the drive key has a non-uniform thickness, and
• wherein a first thickness proximate a middle of the drive key is less than a second thickness proximate a first outer end of the drive key and a second outer end of the drive key.