Hand book of calculations for engineers and firemen : Relating to the steam engine, the steam boiler, pumps, shafting, etc. . 8, andbend it into a circular form resting on its base, so thatthe ends meet. The incline may be continued winding up-wards rcund the same axis and thus winding inclined planes ofany length or height may be constructed. The distance apart of two consecutive coils, measured fromcentre to centre, or from upper side to upper side, (literally theheight of the inclined plane), for one revolution, is the pitchof the screw. The screw is generally employed when severe pressure
Hand book of calculations for engineers and firemen : Relating to the steam engine, the steam boiler, pumps, shafting, etc. . 8, andbend it into a circular form resting on its base, so thatthe ends meet. The incline may be continued winding up-wards rcund the same axis and thus winding inclined planes ofany length or height may be constructed. The distance apart of two consecutive coils, measured fromcentre to centre, or from upper side to upper side, (literally theheight of the inclined plane), for one revolution, is the pitchof the screw. The screw is generally employed when severe pressure is to beexerted through small spaces; being subject to great loss fromfriction it usually exerts but a small power of itself, but derivesits principal efficacy from the lever or wheel work with whichit i-s very easily combined. A screw in one revolution will descend a distance equalto itspitch, or the distance between two threads and the force ap-plied to the screw will move through, in the same time thecircumference of a circle whose diameter is twice the length ofthe lever. Hence the Rule. Hand Book of Calculations. 7. Fig. 19. Kile. The power multiplied by the circumference is equal to theweight multiplied by the pitch. Example. If the distance between the threads be \ inch and the forceof 100 lbs. be applied at the end of a lever 3 feet in length;what weight will be moved by the screw ? See the diagramPig. 19. Twice the length of the lever=6 feet = 72 inches diam. 100 power. to get circum. 28800720021000 divide by pitch 5) .25 5)452160 00432 AriR. in lbs. J2 Hand Book of Calculations. THE SCREW. If the pitch of screw and length of lever be given, tvhat poiverwill be required to move a given weight. Eule. The power multiplied by the circumference is equal to theweight multiplied by the pitch of screw. Example. If the pitch be f of an inch and the lever 2 feet, how muchpower must be applied at the end of the lever to raise a weightof 6 tons. 6 tons=12000 lbs.
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