. The Street railway journal . y concerned—a larger number of small ropes entailsthe use of somewhat wider pulleys on both engine anddynamo, while there are more splices to make and probably a greater frictional loss, due to the differential driv-ing effect, to which reference will be hereafter made. Onthe other hand, it is possible to use pulleys of smallerdiameter, thus more than offsetting the cost of increasingthe width. Moreover, should any one of the ropes fail,the increase of load upon the others will only be practice one and a quarter inch ropes are found togive good satisfac
. The Street railway journal . y concerned—a larger number of small ropes entailsthe use of somewhat wider pulleys on both engine anddynamo, while there are more splices to make and probably a greater frictional loss, due to the differential driv-ing effect, to which reference will be hereafter made. Onthe other hand, it is possible to use pulleys of smallerdiameter, thus more than offsetting the cost of increasingthe width. Moreover, should any one of the ropes fail,the increase of load upon the others will only be practice one and a quarter inch ropes are found togive good satisfaction for driving dynamos of moderatesize when the conditions are favorable to their use, butone inch ropes are also largely used. For larger unitsone and a half to one and three-quarters inch ropes aremore generally adopted, the latter being the largest sizewhich it is advisable to use in any case. In mill drivingpractice at the present time, there is exhibited a notice-able tendency towards the use of smaller ropes, and one. and five-eighths inch is now probably the most usual sizeadopted, while a decade ago two inch was most favored. Pulley Diameter—The rules for the least pulley diame-ter given in the foregoing, viz., thirty rope diameters forcotton and forty rope diameters for manilla, cannot bedisregarded without impairing the durability of therope. If in any case the use of a smaller pulley becomesimperative, the load on the rope should be correspond-ingly reduced; the use of hard, or tightly twisted ropeshould in this case be carefully avoided. As in belt driv-ing, the slack side of the rope should, if possible, alwaysbe uppermost. With a lair length of drive the slack ofof the rope will increase the arc of contact with bothpulleys, thus augmenting the resistance to slipping, whilenecessitating less initial tension and its correspondingdisadvantages. If the slack side is below, the reverseaction takes place, each arc of contact being lessened andthe risk of slipping
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Keywords: ., bookcentury1800, bookdecade1880, bookidstreetrailwa, bookyear1884
