pulley

Definitions

  • WordNet 3.6
    • n pulley a simple machine consisting of a wheel with a groove in which a rope can run to change the direction or point of application of a force applied to the rope
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Webster's Revised Unabridged Dictionary
    • n Pulley (Mach) A wheel with a broad rim, or grooved rim, for transmitting power from, or imparting power to, the different parts of machinery, or for changing the direction of motion, by means of a belt, cord, rope, or chain.☞ The pulley, as one of the mechanical powers, consists, in its simplest form, of a grooved wheel, called a sheave, turning within a movable frame or block, by means of a cord or rope attached at one end to a fixed point. The force, acting on the free end of the rope, is thus doubled, but can move the load through only half the space traversed by itself. The rope may also pass over a sheave in another block that is fixed. The end of the rope may be fastened to the movable block, instead of a fixed point, with an additional gain of power, and using either one or two sheaves in the fixed block. Other sheaves may be added, and the power multiplied accordingly. Such an apparatus is called by workmen a block and tackle, or a fall and tackle. See Block. A single fixed pulley gives no increase of power, but serves simply for changing the direction of motion.
    • v. t Pulley To raise or lift by means of a pulley.
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Century Dictionary and Cyclopedia
    • n pulley Properly, a simple machine consisting of a wheel having a grooved rim for carrying a rope or other line, and turning in a frame, which, when movable, is termed a pulley-block.
    • n pulley A block containing several grooved wheels.
    • n pulley A tackle or apparatus consisting of one or more pulley-blocks with a rope or ropes reeved through them for use in hoisting. The pulley serves to balance a great force against a small one; its sole use is to produce equilibrium; it does not save work, unless indirectly in some unmechanical way. The pulley is a lever with equal arms; but when it turns, the attachments of the forces are moved. Fig. 1 shows a fixed pulley. The equal weights d and e are in equilibrium, because they hang from the equal arms of the lever ab, having its fulcrum at c. Fig. 2 illustrates the principle of the movable pulley. The equal-armed lever, with fulcrum at c, has on one arm the weight d and on the other the force of the stretched string be. If there is equilibrium, this force must be equal to the weight of d. Thus, the total downward pull on f, one arm of the equal-armed lever fg, with fulcrum at h, is twice the weight of d, which must, therefore, be the weight of i to keep it in balance. We may also use the axiom that when a cord is free to move along its length it must be under equal stress in all its parts. Consequently, when a movable block is supported by a number of parallel parts of the same cord, these must bear equal shares of the load. Thus, in fig. 3, the lower block with the weight b brings equal strains upon four stretches of the cord, one of which is balanced by adjective Consequently, the weight of b is four times that of adjective But the effects of friction and of the stiffness of the cord are of great importance in the calculation of the advantages of pulleys. There is a great mechanical advantage in having separate blocks for all the movable pulleys, as in figs. 4 and 5. Thus, in fig. 4, the weight a is balanced over the lowest pulley by the pull on b, and the sum of these forces drawing down the lowest pulley is balanced over the second pulley by the pull on c, which is therefore double the weight at b. Thus, by means of four pulleys a balances a + 2a + 4a + 8a = a (2—1), or fifteen times instead of (as by the arrangement of fig. 3) only four times its own weight. Another arrangement is shown in fig. 5. Here, by means of four pulleys, a balances eight times its own weight.
    • n pulley In anatomy: A trochlea, or trochlear surface of an articulation.
    • n pulley A ligamentous loop which confines or changes the direction of the tendon of a muscle passing through it: as, the digastric muscle of the chin and the superior oblique of the eye both pass through a pulley. See cuts under muscle and eye.
    • pulley To raise or hoist with a pulley.
    • n pulley A pulley which merely tightens the belt but takes off no power.
    • n pulley A pulley built up of segments or sectors.
    • n pulley A segmental pulley; a pulley made in two or more sectors for convenience in casting.
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Chambers's Twentieth Century Dictionary
    • n Pulley pōōl′i a wheel turning about an axis, and having a groove on its rim in which a cord runs, used for raising weights
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Etymology

Webster's Revised Unabridged Dictionary
F. poulie, perhaps of Teutonic origin (cf. Poll (v. t.)); but cf. OE. poleine, polive, pulley, LL. polanus, and F. poulain, properly, a colt, fr. L. pullus, young animal, foal (cf. Pullet Foal). For the change of sense, cf. F. poutre, beam, originally, a filly, and E. easel,
Chambers's Twentieth Century Dictionary
M. E. poleyne—Fr. poulain—Low L. pullanuspullus; acc. to Diez, from Fr. poulie, itself from Eng. pull.

Usage

In literature:

She set down the lamp in its place on the piano, crossed to the pulley-weight clock, and noisily wound it.
"The Return of Peter Grimm" by David Belasco
I have already set in motion a number of influential pulleys, and I am not apt to fail when I make an earnest attempt.
"Fairy Fingers" by Anna Cora Mowatt Ritchie
Every clerk was provided with a chair suspended by pulleys from strong iron rods fastened above.
"Mizora: A Prophecy" by Mary E. Bradley
This cord is stretched tightly over pulleys and moves very rapidly.
"Diggers in the Earth" by Eva March Tappan
In the corner he began to see a confused mass of cords and pulleys.
"Jack" by Alphonse Daudet
With these pulleys well greased, I suppose this will work.
"The Young Castellan" by George Manville Fenn
Rusted in their sockets, they resisted him but he spied a pulley-block within reach and used it as a hammer.
"Blackbeard: Buccaneer" by Ralph D. Paine
There had been the rattling of pulleys and banging of boxes close to my ears, but I heard nothing of all this.
"The Boy Tar" by Mayne Reid
An old term for blocks or pulleys.
"The Sailor's Word-Book" by William Henry Smyth
The rope passed through a pulley which was firmly fixed to the top of the chimney.
"The Book of Stories for the Storyteller" by Fanny E. Coe
When everything was ready, Jimmy hung the aerobike to the steel cable by two ropes, ten feet long, ending in pulleys which ran along the cable.
"The Bill-Toppers" by Andre Castaigne
The pulley you inquired about, I look upon as the greatest invention.
"Blackwood's Edinburgh Magazine, Volume 62, Number 385. November, 1847." by Various
By means of it they draw up the small pulley, and hook it on the window-sill.
"Fire Prevention and Fire Extinction" by James Braidwood
It was evidently caused by the rusty pulley-wheel which I had observed there as we entered.
"Humorous Ghost Stories" by Dorothy Scarborough
Thou art the strong arm of the pulley and the crane.
"Blackwood's Edinburgh Magazine, Volume 62, Number 361, November, 1845." by Various
The ends of the hooks which hung over had pulleys in them, and through the pulleys ran long ropes which hung down to the ground.
"The Doers" by William John Hopkins
Over the shining rims of these pulleys great cables passed, holding suspended in the air a massive stone.
"Friars and Filipinos" by Jose Rizal
The boat was lowered on its pulleys and touched sea.
"The "Adventurers of England" on Hudson Bay" by Agnes C. (Agnes Christina) Laut
G, The trochlea, or pulley over which one of the muscles passes.
"A Treatise on Anatomy, Physiology, and Hygiene (Revised Edition)" by Calvin Cutter
Mr. Liddell does not exactly blame me, but he says we might have had a silver pulley cheaper than the cost of this delay.
"The Works of Robert Louis Stevenson, Volume 9" by Robert Louis Stevenson
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In poetry:

It sees the twining and twisting
Of belts that glisten about
The circle of wheel and of pulley
Like the coils of serpents drawn out.
"No Room For The Poet" by Alexander Anderson
I have learned there's a secret something
That remains yet undefined,
That touches the springs and pulleys
That open the human mind.
"The Desirable Undefined" by Jared Barhite
The shades of girls, all flavoured from their shrouds,
When sunlight goes are sundered from the worm,
The bones of men, the broken in their beds,
By midnight pulleys that unhouse the tomb.
"Our Eunuch Dreams" by Dylan Thomas
Come trooping down King Street, where now may be seen
The pulleys and ropes of a mighty machine;
The weight rises slowly; it drops with a thud;
And, to! the great timber sinks deep in the mud!
"For The Centennial Dinner" by Oliver Wendell Holmes
Each bucket of iron at the wells of the farmyards,
Each bucket and pulley, it creaks and it wails;
By cisterns of farmyards, the pulleys and pails
They creak and they cry,
The whole of sad death in their melancholy.
"The Wind" by Emile Verhaeren

In news:

Grand Saline Police Chief Larry Compton said Pulley was located early Sunday morning in the Dallas area.
From the end of the pulley .
Malcolm, 3, and his father Aubrey Mayfield tried a pulley game at the UCP of Central Florida booth.
Over-Running Alternator Pulley Kit No AK411 Product Image.
Thank you, April Pulley Sayre.
Curtis Pulley 's off-field problems never allowed him to live up to his on-field promise.
The coach reconsidered after getting more details on Pulley 's situation.
Steven Edward Pulley , 21, of Columbia, died Tuesday, Feb 5, 2008, at Maury Regional Hospital.
Pulley would have two years of eligibility remaining.
Conditions at Lexington, Blue Grass Airport, KY. Sources told 27 SportsFirst on Thursday that former Wildcat quarterback Curtis Pulley will not be allowed to transfer to EKU.
Pulley was kicked off the UK team earlier this week, then spoke with Colonels' coach Dean Hood Tuesday.
Two construction workers refurbishing a TriBeCa building were seriously injured yesterday when a cable they were securing snapped, dropping a pulley on top of them, city officials said.
Frank Norman Pulley , 69, 2000 N Wooster Ave, died Saturday, March 6, 1999, at Union Hospital in Dover.
Its unique three-piece design includes two cables per pulley .
For a spit, Dad rescued the shaft from a retired combine and salvaged the machine's 12 pulley as well.
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In science:

The distance between neighboring fixtures, corresponding to node locations for standing waves, is L = 50 cm. A simple pulley and hanging mass system allows the anode to be tensioned with different mass values.
Simple acoustical technique for automated measurement of drift tube anode wire tension
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