Extensible boom mechanism for use with mobile cable salvage apparatus

Apparatus for moving cable into or out of underground and overhead installations, comprising:

• a mobile platform having a cable guiding assembly thereon, including cable pulling wheel means;
• sheave means positionable proximate the location of said cable installation;
• extensible means for movably presenting said sheave means to provide a straight path between said installation and said sheave and a second straight path from said sheave to said wheel;
• said extensible means including master cylinder means having a fixed reference for movement in an extension direction and a retraction direction;
• first piston means in said master cylinder, having means for displacing oil in said master cylinder for movement in said extension direction and a first piston area for movement in said retraction direction;
• an auxiliary cylinder on said fixed reference, including an auxiliary piston means having means for displacing oil in said auxiliary cylinder and an auxiliary piston area for movement in said retraction direction;
• and
• hydraulic means for provided fluid to said master cylinder and said auxiliary cylinder in series, sequential displacement first in said master cylinder and then in said auxiliary cylinder and wherein said auxiliary piston area is greater than said first piston area, whereby fluid pressure in the extension direction sequentially moves said first piston and thereafter said auxiliary piston and fluid pressure in the retraction direction reverses the sequential order of movement of said pistons.

Apparatus for moving cable into or out of underground and overhead installations, comprising:

• a mobile platform having a cable guiding assembly thereon, including cable pulling wheel means;
• sheave means positionable proximate the location of said cable installation;
• extensible means for movably presenting said sheave means to provide a straight path between said installation and said sheave and a second straight path from said sheave to said wheel;
• said extensible means including master cylinder means having a fixed reference for an extension direction and a retraction direction;
• an auxiliary cylinder on said fixed reference, including an auxiliary piston means having means for displacing oil in said auxiliary cylinder and an auxiliary piston area for movement in said directions;
• second nested piston means in said first piston means, having second oil means for displacing oil in said first piston means for movement in said extension direction and a second piston area for movement in said retraction direction;
• and
• hydraulic means for provided fluid to said master cylinder and said auxiliary cylinder in series, to permit sequential displacement in said first oil means, said second oil means and then said auxiliary cylinder, and wherein said auxiliary piston area is greater than said first piston area, whereby fluid pressure in the extension direction sequentially moves said first piston and thereafter said second piston and thereafter said auxiliary piston, and fluid pressure in the retraction direction reverses the sequential order of movement of said pistons.

Apparatus for moving cable into or out of underground and overhead installations, comprising:

• a mobile platform having a cable guiding assembly thereon, including cable pulling wheel means;
• sheave means positionable proximate the location of said cable installation;
• extensible means for movably presenting said sheave means to provide a straight path between said installation and said sheave and a second straight path from said sheave to said wheel;
• stiff-leg means for providing rigid resistance to movement of said sheave toward said installation during operation of said cable pulley wheel means;
• and
• safety means for providing brake force on said extensible means in said extension direction, said safety means comprising (a) a radial tapered groove having a maximum depth in the axial direction toward said sheave means, and (b) circumferentially extending compression resistant means sized to said maximum depth, said compression resistant means being compressed to exhibit drag on said second piston means during movement of said second piston in said extension direction.

Apparatus for moving cable into or out of underground installations, comprising:

• a mobile platform having a cable guiding assembly thereon, including cable pulling wheel means;
• sheave means positionable proximate the location of said cable installation;
• and comprising:
• master cylinder means having a fixed reference for an extension direction and a retraction direction;
• first nested piston means in said master cylinder, having first oil means for displacing oil in said master cylinder for movement in said extension direction and a first piston area for movement in said retraction direction;
• an auxiliary cylinder on said fixed reference, including an auxiliary piston means having means for displacing oil in said auxiliary cylinder and an auxiliary piston area for movement in said retraction directions;
• second nested piston means in said first piston means, having second oil means for displacing oil in said first piston means for movement in said extension direction and a second piston area for movement in said retraction direction;
• and
• hydraulic means for providing fluid to said master cylinder and said auxiliary cylinder in series, to permit sequential displacement in said first oil means, said second oil means and then said auxiliary cylinder, and wherein said auxiliary piston area is greater than said second piston area, which is greater than said first piston area, whereby fluid pressure in the extension direction sequentially moves said first piston and thereafter said second piston and thereafter said auxiliary piston, and fluid pressure in the retraction direction reverses the sequential order of movement of said pistons.