Abstract: An improved bundle conductor stringing block having a main frame constructed essentially of structural steel components and including a cantilever suspension yoke positioned to form a tow-line receiving passage through which a helicopter can dispense a conductor tow-line onto a central one of multiple sheaves. Guide members pivoted to the opposite sides of the tow-line passage guide the tow-line onto the central sheave and include toggle spring device engageable by a running board at the trailing end of the tow-line to engage these members and pivot them in either direction to retracted positions along the block side frame.

Abstract: Stringing block threading apparatus for use in uncoupling a junction in a conductor hauling line and inserting a threading loop therein previously assembled through the throat of a stringing block. The hauling line is advanced along power line towers by a helicopter and the advance sections of this line are separably joined by a double ended coupling. This coupling is deposited into the threading apparatus atop each tower where it is automatically disconnected from the hauling line allowing enlargements on the released section ends to separate and become trapped in respective mating couplings at the opposite ends of the threading loop and the leading one of which is of the same double ended construction as the one deposited in the threading apparatus by helicopter. This coupling is deposited in the next threading apparatus for a repeat threading operation.

Abstract: A conductor stringing block adapted to be threaded with a hauling line dropped by helicopter and having a suspension yoke connected at its ends to the opposite sides of the block frame. The yoke includes a threading passage which is normally closed by a latch effective to transmit load forces crosswire of the passage. The upper end of the threading passage is equipped with an outwardly and upwardly inclined extension to receive and feed a helicopter-dispensed hauling line into the passage. Upright extensions projecting downwardly from the lower end of the passage flex to pass a power line running board and guide the hauling line as it drops from the threading passage onto an underlying sheave of the stringing block. The yoke assembly is securable crosswise of the upper end of a conventional stringing block in lieu of the conventional suspension yoke thereby converting the conventional block to use with helicopter threading equipment.

Abstract: A releasable connector is provided in an aerially placed pulling cable which is deposited in a catching device wherein the connector is disconnected and reconnected to connectors carried by the ends of a preplaced loop cable passing through the area to be strung, all responsively to forces of cable stringing. The particularly configured catcher provides a guiding through to support the pulling cable and its connector and upon appropriate positioning of the cable therein to release the connector so that the rearward portion of the pulling cable moves rearwardly by reason of its gravity bias to connect with one end of the preplaced loop cable and the forward end of the pulling cable moves forwardly to connect with the forward end of the loop cable to reform a continuous compound pulling cable with the loop cable incorporated therein.