Chain Casing and Chain Tensioning Assembly

A chain tensioning assembly for providing a tensioning action to a Jane part, such as the pulling chain part or the returning chain part, the chain tensioning assembly comprising:

• a frame tube fastening element for fastening of the chain tensioning assembly to a frame tube, preferably a bottom stay,
• a tensioning arm for providing a tensioning relative to the chain in which the tensioning arm is movably arranged relative to the frame tube fastening element,
• tensioning means for providing a bias to the tensioning arm,
• a first guide sprocket, and preferably a 2nd guide sprocket, for guiding of the chain, in which
• at least one guide sprocket is arranged at the tensioning arm in order to provide a tensioning action relative to the chain, and in which
• the first guide sprocket and the 2nd guide sprocket are functional for guiding under bias during use, of one of the chain parts as tensioned part, preferably the returning chain part, such that the tensioned part is longer than the other part, and
• the frame tube fastening element for fastening of the chain tensioner assembly to the frame tube functions in coaction with a fastening provision of the frame tube, such as the bottom stay.