Positioning carrier for vertical rail

A positioning carrier for attaching to a rail having a rib, said carrier comprising:

• a housing, said housing including a bore formed in said housing,
• a frame attached to said housing, said frame being engaged onto said rib of said rail and to be moved up and down along said rail, said frame including a compartment formed in said frame for receiving and engaging with said rib of said rail, and said frame including a hole formed in said frame and aligned with said bore of said housing,
• a bracket engaged into said compartment of said frame and contacted and engaged with said rib of said rail,
• a seat attached to said housing, said seat including a passage formed in said seat and aligned with said hole of said frame and said bore of said housing, and said seat including a curved surface formed in said seat,
• a latch engaged through said hole of said frame and said bore of said housing and said passage of said seat,
• a shaft attached to said latch,
• a spring biasing member engaged onto said latch and engaged between said shaft and said seat, and
• a cam member including a groove formed in said cam member for receiving and engaging with said shaft and for contacting and engaging with said curved surface of said seat, and for actuating and forcing said frame and said housing and said seat toward each other in order to anchor and retain said frame and said housing to said rib of said rail when said cam member is rotated in one direction relative to said seat and said housing, and for releasing said frame and said housing and said seat from each other when said cam member is rotated in another direction relative to said seat and said housing.