US 4,252,214 A · Safety descent device

Abstract

A fall prevention safety device for attachment to a harness worn by a workman for providing a safely controlled descension rate from an elevated structure includes a cable having one end connected to the harness and strung around a double pulley system having an upper pulley mounted to the elevated structure and a lower pulley mounted to the upper end of a vertically reciprocal plunger which falls substantially unimpeded into a hydraulic cylinder. The cylinder substantially resists upward withdrawal of the plunger. The other cable end is connected to the upper pulley yoke such that during ascent of the workman up the structure, the lower pulley and plunger move downwardly and take up cable slack. If the workman slips and falls at any point during ascent, the cable immediately and automatically provides descension at a controlled rate determined by the resisted withdrawal rate of the plunger as the cable now pulls the lower pulley upward. The hydraulic cylinder includes a bypass line with ports communicating with the hydraulic cylinder at upper and lower compartments above and below the inner plunger end having a seal therearound defining the two compartments. The inner plunger end also carries a one-way valve which is in an open condition during downward plunger movement and is closed by fluid pressure upon initiation of workman descent.

Claims20

Dependent claims

A fall prevention safety device for attachment to a harness worn by a workman for providing a safely controlled descension rate from an elevated structure comprising:

retraction means anchored relative to said elevated structure and having a reciprocal actuator having one preferred direction of motion, and means resisting the other direction of motion of said actuator;
interconnection means connecting said harness to said actuator such that during ascent of said workman along a predetermined ascension path up said elevated structure said actuator moves in said one preferred direction for continuously adjusting to the increasing height attained by said workman during said ascent and for compensatingly maintaining a taut non-slack condition of said interconnection means, descent from any and all points along said path being immediately and automatically dynamically limited to a descension rate controlled by said means resisting motion of said actuator in said other direction.

A fall prevention safety device for attachment to a harness worn by a workman for providing a safely controlled descension rate from an elevated structure, comprising:

fluid cylinder means anchored relative to said elevated structure and including plunger means reciprocally movable therein and one-way valve means actuatable to an open position by movement of said plunger means in one direction and actuatable to a closed position by movement of said plunger means in the other direction, said open position of said one-way valve means providing minimal fluid resistance to movement of said plunger means, said closed position of said one-way valve means providing substantial fluid resistance to movement of said plunger means;
interconnection means connecting said harness to said plunger means such that ascension of said workman along a predetermined path up to said elevated structure enables movement of said plunger in said one direction whereby to open said one-way valve means and afford free ascension of said workman along said predetermined path, and such that descension of said workman moves said plunger means in said other direction whereby to close said one-way valve means and afford slow descension of said workman controlled by said resisted movement of said plunger in said other direction.

A fall prevention safety device for attachment to a harness worn by a workman for providing a safely controlled descension rate from an elevated structure, comprising:

an elongated cylinder vertically mounted to said structure and having a closed bottom end;
an elongated plunger extending through the top end of said cylinder and vertically reciprocal therein, said top end of said cylinder being sealed around said plunger;
fluid contained in said cylinder;
sealing means carried by said plunger adjacent the end thereof interior of said cylinder and defining upper and lower separate sealed compartments on either side of said sealing means within said cylinder adjacent said top and bottom ends thereof, respectively, which compartments change in volume as said plunger reciprocates;
one-way valve means actuated to an open condition by fluid pressure in said bottom compartment in response to downward movement of said plunger to permit substantially unimpeded downward movement of said plunger, and actuated to a closed position by fluid pressure in said upper compartment in response to upward movement of said plunger to substantially resist upward plunger movement;
a pulley and cable system comprising a lower pulley connected by a yoke to the upper end of said plunger and an upper pulley connected by a yoke to said elevated structure at a position spaced above said lower pulley, and a cable having one end connected to said harness and then strung at least once around said upper and lower pulleys and then connected at its other end to said upper pulley yoke, such that during ascent of said workman the separation of said pulleys increases and said plunger falls substantially freely in said cylinder, and during descent of said workman the separation of said pulleys decreases as said lower pulley is pulled upwardly by said cable which upward movement is substantially retarded by fluid resistance to upward plunger movement, said substantially free downward movement of said plunger enabling said lower pulley to take up slack in said cable during said ascent of said workman to provide a continuously taut condition of said cable and provide immediately retardation upon descent.

3 more elements

Dependencies are inferred from the claim text.

Safety descent device

Life of this patent

Safety descent device

Life of this patent

Abstract

Claims20