Actuating mechanism for fluid displacement and pressurizing device

An actuating mechanism for pressurizing a device, said mechanism comprising a housing;

• a carrier member disposed generally in the housing and removable therefrom, said housing and said carrier member being non-integral, distinct components;
• a threaded screw structure slidably displaceable through the housing;
• a nut member generally in the carrier member, said nut member having partial threads and being selectively engageable and disengageable with the threaded screw structure;
• at least one link member engaged with the nut member;
• and link structure which couples the carrier member to the at least one link member, wherein the nut member and at least one link member are pivotable relative to the carrier member, wherein said actuating mechanism is configured such that the nut member is selectively moveable relative to the screw structure to provide selective threaded engageability of the partial threads with the screw structure, said nut member and said carrier member being distinct components wherein said nut member is shiftable to selectively engage and disengage the threaded screw structure while said carrier member remains stationary.