Coupling apparatus

An assembly for coupling a traction member to a second member and adapted to effect release therebetween in delayed response to tractive force exerted between said members which exceeds a predetermined limit, comprising in combination:

• axially slidable coupling portions on said members, one of which is defined by an opening in said traction member and the other by a tongue forming part of said second member and inserted into said opening, said tongue having an abutment surface facing in the direction of axial withdrawal of said tongue from said opening;
• a housing slidable with respect to said traction member back and forth along said direction of axial withdrawal, a lock bolt movably carried by said housing for movement into and out of engagement with said abutment surface and resilient means normally urging said lock bolt in a direction to engage said abutment surface, and spring means connecting said housing and said traction member for urging said housing in that direction opposite to said direction of axial withdrawal, said housing being guided within said traction member and said housing and traction member having mutually engageable stop portions whereby to allow movement of said housing only to a certain point in opposition to said spring means which corresponds to partial withdrawal of said tongue, and said spring means being of sufficient strength to prevent movement of the housing to said certain point unless a tractive force is exerted between said traction member and said second member which exceeds said predetermined limit;
• time delay means carried by said traction member for moving said lock bolt out of engagement with said abutment surface only after a predetermined time delay after said housing has reached said certain point and has returned to its initial position;
• and
• means connected to said time delay means and moved by said housing member for actuating said time delay means only in response to movement of said housing at least substantially to said certain point, whereby initiation of automatic release action cannot be effected except in response to tractive forces exceeding said predetermined limit, said time delay means including a first member shifted in one direction in response to movement of said housing in the withdrawal direction and return spring means opposing such shifting of the first member to urge it in return direction opposite said one direction, motion-retarding means engaging said first member for slowing its return motion as effected by said return spring means, and a second member adapted to participate in return motion of said first member ultimately to engage and release said lock bolt, said means for actuating said time delay means comprising latch means for connecting said first and second members when said housing is substantially at said certain point.