A New Form of Worm Gear.
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A worm gear possessing a considerable amount of originality, and for which important claims are made, has been produced by Messrs. Fleury and Gauthier, and is now being tested by a leading French factory with a view to its adoption on both pleasure and commercial vehicles. The Fleury gear has a worm operating on the side of the worm wheel, as in the ease of a bevel gear, this lateral mounting reducing the overall dimensions of the housing considerably compared with the ordinary worm having a tangential action on the worm wheel. While it is admitted that this conception is not entirely new, it is maintained that this mechanism has never been worked nnt theoretically nor constructed with the necessary precision. There are worms operating between two worm wheels, but this arrangement is theoretically incorrect, and can only be made to work by leaving a considerable amount of play in the gearing. The Fleury lateral-worm gear makes use of but one worm wheel ; the worm places itself in the required position, at the correct distance from the centre of the wheel, and it is impossible to place it otherwise.
The Fleury gear has a thread of unequal nitch, the variation being constant • and regular. The result gained by this variation is that the worm follows up the retreating tooth, and thus the full power of the worm is always exerted on the full strength of the tooth. Another important feature is that the teeth in contact with the worm are always immersed to-their full depth. In the ordinary worm-wheel gear only one tooth can he in full contact, while the others vary, the amount of contact before and after the tooth in B10 full contact depending on the size or diameter of the wheel.
Several of these gears have been subjected to prolonged tests, twin which it is evident that they are as silent as the,most carefully cut worm gears, and that their efficiency is not less than 95 per cent. Lubrication offers no difficulty whatever. In one particular case a gear with a reduction of 1 to 4 was run continuously for a week under full load without any signs heating and without an appreciable wear.