Apparatus for controlling movement of a tether in a conduit

Apparatus for controlling movement of a tether in a conduit comprising, in combination:

• a. a frame;
• b. means mounted on said frame for deploying and retrieving a tether;
• c. a plurality of frictional braking systems operable during tether deployment, each said system being able to exert a different, continuously variable range of constant resistance against deployment;
• and,
• d. means for engaging an opening in a conduit.

Apparatus for controlling movement of a tether in a conduit, wherein said conduit has an opening in a generally horizontal surface, said apparatus comprising, in combination:

• a. a frame;
• b. means mounted on said frame for deploying and retrieving a tether;
• c. means extensible from said frame for engaging said conduit opening's rim;
• and,
• d. a plurality of braking systems operable during tether deployment, each said system being able to exert a different, continuously variable range of constant resistance against deployment.

Apparatus for controlling movement of a tether in a conduit, wherein said conduit has an opening in a generally horizontal surface, said apparatus comprising, in combination:

• a. a frame;
• b. means mounted on said frame for deploying and retrieving a tether;
• and,
• c. means extensible from said frame for engaging said conduit opening's rim, wherein said opening engaging means comprises a pair of rigid parallel members extensible from said frame and mating securely with an elongate member placed across said opening, said elongate member having a length exceeding the width of said opening and having a plurality of projections preventing lateral movement of said elongate member in said opening, and wherein at least one of said rigid parallel members includes means for securely binding an air gap thereto.

Apparatus for controlling movement of a tether in a conduit, wherein said conduit has an opening in a generally horizontal surface, said apparatus comprising, in combination:

• a. a frame;
• b. means mounted on said frame for deploying and retrieving a tether;
• and,
• c. a member extensible from said frame, said extensible member mating securely with an elongate member placed across said opening, said extensible member having a distal end and means for raising said end with respect to said elongate member, thereby using the force of the weight of said apparatus in securely mating said extensible member with said elongate member.