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“FASSI PATENT” WINCH TORQUE LIMITER DEVICE

With issue and enforcement of European safety standards EN12999, the adoption not only of cable limiting devices, but also of a safety device against risks deriving from direct or indirect overload applied to the winch have become compulsory. Most of the methods used are based on devices such as Belleville washers or strain gauges, which read the deformation of the winch fixing plate as a consequence of the cable fall given by the lifted load. However, we know by direct experience that these systems have shown considerable shortfalls in terms of reliability, precision, correct reading of stresses and maintenance of the original settings, often obliging the users to disable them in order to work. In line with its own mission to offer state-of-the-art safety systems that are also safe, precise and reliable, the Fassi R&D department has studied and created an innovative device that responds to all these needs. The Fassi winch torque limiting system is covered by a patent.

The basic features of this system are as follows: the winch (A) is bolted to a plate (B) mounted using tie rods (C) fixed to the underside of the outer boom by means of welded hears (D) and on the front side of the plate, fixed to a lug, a load cell (E) is positioned, connected to a miniaturised electronic card (F). Based on the load lifted by the winch cable, the plate moves slightly forward and acts on the load cell which, on reaching the preset reference value, sends a message to the miniaturised electronic card ( which is fully

resin coated to guarantee maximum reliability and seal). The card processes the message and transmits it to the electronic main control unit (“FX”) which in turn activates or deactivates the crane/winch lifting functions. The load cell also manages activation of the mechanical cable lifting stroke end function. When the counterweight (K) comes into contact with the beak of the pulley with an evolving circular profile (J) and the pull on the cable reaches the preset reference value of the load cell, the electronic card activates blockage of the crane functions related to the limit switch. The system also allows automatic handling of any de-rating of the winch capacities for its use on both the crane and a hydraulic jib.

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A

B

E

F

G

H

D C

The device has the following components: A) Winch B) Sliding support C) Tie rods D) Welded hears E) Load cell F) Miniaturised

electronic card G) Micro switch for

rope stroke end on winch drum

H) System for the activation of the micro switch on winch drum

I) Intermediate cable guide pulley

J) Pulley at boom tip, with evolving circular profile

K) Counterweight

Normal working conditions Activation of the mechanical cable lifting

stroke end

The application of the winch, which is widely used in cranes for the building sector, responds to Fassi’s motto of “Cranes without compromise”: its levels of safety, reliability and performance most certainly make it unique!!! 21-2

E

I

G

H

F

J

K