Machine drawing; a practical guide to the standard methods of graphical representation of machines, including complete detail drawings of a duplex pump and of a direct-current generator . cessive amount of rubbing on the sidesof the belt, as well as strain caused by the twisting. Crossing and Quarter- Twisting. It is well to use as few crossedand quarter-twist belts as conditions will permit. In quarter-twistbelts, the side angle, where the belt leaves the pulley, should be keptunder 25°, as considerable power is lost in side slipping. For the leastdistance between the shafts a safe value is o
Machine drawing; a practical guide to the standard methods of graphical representation of machines, including complete detail drawings of a duplex pump and of a direct-current generator . cessive amount of rubbing on the sidesof the belt, as well as strain caused by the twisting. Crossing and Quarter- Twisting. It is well to use as few crossedand quarter-twist belts as conditions will permit. In quarter-twistbelts, the side angle, where the belt leaves the pulley, should be keptunder 25°, as considerable power is lost in side slipping. For the leastdistance between the shafts a safe value is obtained if the distance ismade not less than 2\ times the diameter of the larger pulley. Anarrow belt gives better results than a wide one, on twisted belting. GEARSGeneral Theory of Gears. Fig. Ill represents a pair of disksfastened to shafts A and B, respectively, and touching at the pointP. If these disks be pressed tightly against each other, sufficientfriction will be produced between them to cause one to drive theother. The number of revolutions B would make in a given time,would be to the number of revolutions made by A as AP is to BP; or, Revolutions B _APRevolutions A BP. MACHINE DRAWING 133 Such friction disks will transmit but very little power without slip-ping; and even when required to transmit small power, cannot bedepended upon to drive positively, as the least wear or loss of adjust-ment is liable to make them teeth are provided on eachdisk, such that they will lock to-gether and make it sure that whenone disk is rotated the other mustmove also, without regard towhether the disks are pressed tightly Fig. m. Diagram of Sk^iTcTear Prin-together or not. In fact, it is desir- cip e able that this side pressure be avoided, in order to preventexcessive friction in the bearings of shafts A and B. Any shapes whatsoever of teeth would answer, provided theyinterlocked, so far as positive driving is concerned. But in orderthat the revolutions of the shafts sha
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Keywords: ., bookcentury1900, bookdecade1910, bookpublis, booksubjectmachinery
