Safety plant for a cable stretching machine, corresponding method and stretching machine using said plant

Abstract

Safety plant for a stretching machine (1 1) of the brake type comprising a negative brake (22) which can be selectively activated and de-activated so as to constrain and respectively allow the rotation of at least one capstan (12) which supports cables, a pumping device (24) connected to the negative brake (22) and configured to de-activate the latter during the normal use of the stretching machine (11), putting a working fluid under pressure, pressure energy accumulation means (32) of said working fluid, and a maximum pressure valve (18) configured to regulate the working pressure of a hydraulic motor (13) for controlling the twisting torque applied to the capstan (12). The plant also comprises a motorized drive device (19) connected to the maximum pressure valve (18) and provided to selectively regulate the action of the latter on the hydraulic motor (13), even in a breakdown condition of at least the pumping device (24), in order to maintain the working pressure of the hydraulic motor (13) and to maintain the negative brake (22) de-activated by the intervention of the pressure energy accumulation means (32).

Description

technical field [0001] The invention relates to a safety device for a cable tensioning machine. [0002] In particular, the safety device consists of a hydraulic circuit, preferably but not exclusively applied to a stretching machine of the brake type suitable for applying a controlled tension to the wire during the stretching step. According to the invention, the safety device is provided with a safety device which intervenes in the event of failure of a device component or in an emergency situation. [0003] The invention also relates to a corresponding method for safety control of a cable drawing machine, and a drawing machine using said safety device. Background technique [0004] Stretching machines are known, for example for stretching high voltage electric lines, railway lines or other lines, usually overhead lines; this stretching machine provides so-called "brake" stretching of cables by means of a plurality of winches, The cables to be stretched or respectively r...

AI Technical Summary

Problems solved by technology

However, the action to preserve the tension is not coordinated with the stop of the moving device

[0017] Thus, there is an overload on the cable, and the possibility of damaging or breaking the cable, which has serious implications for operators, especially those on overhead or railway equipment, and also for everything connected to or under the cable. Obvious safety risk and problem: this defeats the safety function of negative brakes in practice

[0022] In particular, when electrical or hydraulic components of the stretching machine fail, and if the distributor valve is of the non-holding action type, the pressure of the working fluid generated by the pressure energy accumulator prevents the capstan rotation from being suddenly blocked, thereby following The negative recoil is cleared, but in any case opening the maximum pressure valve will cause a loss of tension in the cable

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