Lubrication pump

A lubrication pump comprising:

• a housing defining an internal housing bore having a longitudinal axis, the housing having a supply fluid passage and an exhaust fluid passage;
• a cylinder sleeve disposed within the internal housing bore, the cylinder sleeve having an internal cylinder surface defining an internal cylinder bore;
• a piston slidably movable within the internal cylinder bore along the longitudinal axis, the piston cooperating with the internal cylinder surface to define a fluid chamber;
• and
• a drive shaft having an eccentric cam, the eccentric cam being rotatable with the drive shaft relative to the housing and configured to drive the piston in reciprocating motion along the longitudinal axis within the internal cylinder bore between an upstroke position and a downstroke position;
• where the cylinder sleeve has an inlet fluid passage in fluid communication with the supply fluid passage of the housing for permitting fluid to enter the fluid chamber, and the cylinder sleeve has an outlet fluid passage in fluid communication with the exhaust fluid passage of the housing for permitting the fluid to exit the fluid chamber;
• and
• where the cylinder sleeve is axially adjustable relative to the internal housing bore to vary an axial location of the inlet fluid passage relative to the piston in the upstroke position to thereby vary an amount of fluid output flow from the fluid chamber.