Chain Wear Indicator 1

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In this mechanism one Sprocket Wheel (yellow), two pulleys, and a Synchronous belt are added to the main Sprocket Wheel (Blue). Because of the presence of spring in the end of the shaft, and a pair of helical gears (internal and external), the chains between two Sprocket wheels and synchronous belt are permanently under tension. The yellow pulley is attached to the shaft, but the red pulley can rotate around the shaft. Also, the internal helical gear and the wear indicator can have axial displacement on the shaft. If the chain length increases due to wear happened , the yellow sprocket and green shaft wheel can rotate inside the red pulley. As a result, the internal helical gear and the wear indicator move in the direction of the shaft. This movement shows the amount of wear in the chain ( The colorful Pin is fixed in hoist body ) and triggers the limit switch. If the chain wears too far, the switch turns on and the alarm sounds. By periodical measuring of the changes in the location of the indicator, we can measure the wear rate in the unit of time and we can estimate the replacement time of the chain before its final breakdown. According to the ISO 7592 standard and empirical experiences the indicator and pin can be calibrated and the limit switch can be adjusted. During setup, chain guide and hold down should be installed around sprocket wheel to ensure the correct installation according to the drawing. The synchronous belt must be inextensible by internal fiber and install with pre load ( Maybe need Belt tensioner ). Some of the other benefits of this system are the following: • Both visual and electrical limit switch are applicable; • This design increases the engagement between the chain and the sheave ; • and it decreases the shock load in chain and sheave drive and reduces the chain wear ( because the load of the chain increases in 2 steps) • All the elements of this mechanism are mechanical . • We can add the linear encoder the indicator for monitoring the wear rate in duration of usage .