The end positions of a crane hoist are defined by the corresponding angle of rotation of the drive shaft. These revolutions can be translated into the angle of rotation of a cam limit switch. If, for example, the defined angle of rotation for the lower operating position of a crane is now reached, a signal can be transmitted to the cabin so that the lowering of the crane can be interrupted. If the crane operator reacts too late, a predefined angle of a so-called emergency end position is reached, whereby the drive is automatically stopped and the downward travel is interrupted. The rotation of the winch shaft is transmitted to the shaft of the gear limit switch, thus actuating the corresponding switch contacts at the previously set position.
In addition to the gear limit switch for limiting the lifting heights, cross lever limit switches can also be used. These are used to limit the movement of the trolley and/or the crane. In addition to the basic stop function of the cross travel for each direction via 2 contacts, we are also able to implement a slow down and stop function via 4 contacts. Furthermore, special switching configurations allow the exclusion of defined areas outside the travel range of the crane.
On installations with jibs, the jib must be mechanically limited. Here, geared limit switches can provide safe pre- and limit switching of a respective jib stage. Especially our FCN gear limit switches are used in crane construction.
Each cam is equipped with its own adjusting screw (planetary gear). The individual screws operate only the cam connected to the screw without affecting the position of the other cams. The adjustment is made by simply turning the screw with a normal screwdriver. In this way, all cams can be adjusted safely and precisely to the desired position. As an additional service, we also offer pre-adjustment of all cams for our customers. Here, after the cams have been set, the shaft is fixed and only released again after installation at a predefined position in the system. This saves time and avoids errors during commissioning.
A completely new system of connecting the individual cams in the cam switch unit minimizes friction and at the same time increases the switching accuracy and reliability of the cams. The gear limit switches of the FCN series can be equipped with a maximum of 5 contacts. More than 15 different actuating cams are now available for actuating each contact. The following is an excerpt of our most frequently used cam types: