. Practical physics. Fig. 134. Train of gearAvheels Fk: 135. The wormo-ear This device is usedmost frequently whenthe primary object is todecrease speed rather than to multiply force. It will be seen that thecrank handle must make n turns while the cogwheel is making one. Theworm-gear drive is generally used in the rear axles of auto trucks. 141. The differential pulley. In the differential pulley (Fig. 136) anendless chain passes first over the fixed pulley A, then down andaround the movable pulley C,then up again over the fixed pul-ley B, which is rigidly attachedto A, but differs slightly f
. Practical physics. Fig. 134. Train of gearAvheels Fk: 135. The wormo-ear This device is usedmost frequently whenthe primary object is todecrease speed rather than to multiply force. It will be seen that thecrank handle must make n turns while the cogwheel is making one. Theworm-gear drive is generally used in the rear axles of auto trucks. 141. The differential pulley. In the differential pulley (Fig. 136) anendless chain passes first over the fixed pulley A, then down andaround the movable pulley C,then up again over the fixed pul-ley B, which is rigidly attachedto A, but differs slightly from itin diameter. On the circumfer-ence of all the pulleys are projec-tions which fit between the links,and thus keep the chains from slip-ping. When the chain is j^i^Heddown at E, as in Fig. 13 G, (2),until the upi^er rigid system ofpulleys has made one completerevolution, the chain between theupper and lower pulleys has beenshortened by the difference be-tween the circumferences of the. Fig. 13G. The differential pulley 120 WORK AND MECHAXICAL ENERGY pulleys ^l and B, for the chain has been pulled up a distance equal to thecircumference of the larger pulley and let down a distance equal to thecircumference of the smaller pulley. Hence the load R has been lifted byhalf the difference between the circumferences of A and B. The mechan-ical advantage is therefore equal to the circumference of A divided byone half the difference between the circimiferences of A and B. QUESTIONS AND PROBLEMS 1. A 1500-pound safe must be raised 5 ft. The force which can beapplied is 250 lb. What is the shortest inclined plane which canbe used for the purpose? 2. A 300-pound barrel was rolled up a jilank12 ft. long into a doorway 3 ft. high. What forcewas applied parallel to the plank? 3. A force of 80 kg. on a wheel whose diameteris 3 m. balances a weight of 150 kg. on the the diameter of the axle. 4. If the capstan of a ship is 12 in. in diameterand the levers are 6 ft. long, wha
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectphysics, bookyear1922
