Backlash free shear joint

A backlash free shear joint comprising:

• a flanged hub member having a hub portion adapted to be secured to a shaft and a flange extending from said hub in a direction substantially normal to the longitudinal axis of said hub portion, said flange being provided with at least two colinear radially disposed holes, from the hub;
• a pair of side plate members, each member having at one end a portion dimensioned to encircle said hub portion with a predetermined clearance thereabout and having at its other end attachment means for attaching said side plate to utilization structure, said side plates being provided with holes configured to align with said flange holes, said holes being colinear and at predetermined radii r.sub.A, r.sub.B from said attachment means, where r.sub.B >r.sub.A ;
• at least two shear pins, each shear pin being located in the aligned pair of said flange and side plate holes for preventing relative motion between said flanged hub and said side plate members until a predetermined differential force between the hub and the side plate shears said pins;
• said clearance of said side plates about said hub being selected such that at a predetermined loading between said flanged hub and said side plate member said first shear pin shears prior to the hub engaging the encircling portion of the side plates, and thereafter said side plate members rotate about said second shear pin until the side plate encircling portions engage the hub with said second pin shearing if said loading exceeds a second predetermined value;
• and
• wherein said side plate members are formed of a selected material in a predetermined shape such that they are capable of flexing in a direction parallel to the longitudinal axis of said shear pins whereby galling, reseizing or high friction caused by the sheared edges of a sheared pin is eliminated.