Abstract: An equalizing rigging block for use with a synthetic roundsling is disclosed. The rigging block includes in preferred embodiments (a) a flatter and wider sheave to better accommodate a wider or flatter cross-section synthetic roundsling; (b) higher side sections for the sheave; and (c) a plurality of stacked bearings along the rigging block axis to provide enhanced lateral stability of the rigging block. In preferred embodiments, the rigging block sheave is manufactured from a synthetic material, such as plastic. The equalizing rigging block exhibits improved characteristics of holding a synthetic roundsling within the rigging block, and of reducing wear and tear on the roundsling.

Abstract: The outer race of a roller bearing sheave is omitted so that the bearings are in direct engagement with a line. A retainer for the ends of the bearings is provided to allow the bearings to rotate and recirculate around an inner race. The rollers deflect portions of the line equally to equalize the load and to prevent high stresses on individual rollers.

Abstract: A cable made up of a plurality of conductors twisted together is drawn through the extrusion head of an extruder which applies a sheath of plastic or elastomeric material to the cable. From the extruder, the cable passes through a tube having a heated section in which the sheath material is cured followed by a cooling section. The sheathed cable is rotated about its axis to twist the cable. Guide wheels over which the cable passes have on their circumferences a multiplicity of pairs of rollers which are engaged by the cable and have their axes tangential to the circumference of the wheel so as to support the cable while permitting rotation of the cable about its axis. In one embodiment, a device for drawing the cable from the extruder, while twisting it, has a pair of endless belts which grip the cable between them and a motor for driving the belts. The belts and driving motor are mounted in a motor driven rotatable cage which rotates about the axis of the cable.

Abstract: An apparatus for retrieving marine seismic cable uses an endless traction member which defines a helical path of at least two turns for pulling the cable in a uniform fashion without forming overlapping layers.

Abstract: A pulley or sheave that is lagged with rubber or rubber-like material, has two disc-like members which are disposed broadside to each other and secured together to form an annular groove for receiving and guiding a strand of material. At their centers, the members have bearing means to accommodate a spindle. In the annular groove for the strand of material the members have oppositely disposed wall portions characterized by re-entrant side walls. A wear strip of relatively soft, resilient material such as rubber having an elongated rib occupies the annular groove, the rib being accommodated in and frictionally seized by the reentrant side walls. The wear strip has abutted ends, and presents an annular exterior space for engagement with the strand of material that is being handled.