Pulley

About: Pulley is a research topic. Over the lifetime, 51636 publications have been published within this topic receiving 178220 citations. The topic is also known as: drum & block.

Wind-drag type climber

Abstract: A wind-drag type climber includes a base frame, a suspended wheel, a handlebar assembly, two swing arms each carrying a pedal thereon, a driving shaft, and a speed-increasing mechanism interconnecting the wheel and the driving shaft so as to rotate the wheel at a speed greater than that of the driving shaft. The wheel has a plurality of generally radially extending wheel blades which create air impedance to the rotation of the wheel. A drawing member is fastened to the free ends of the swing arms at two ends thereof and has two chain-like sections engaged with the two sprockets of the driving shaft, and a cable-like section extending around two aligned lower pulleys. The sprockets are sleeved rotatably on the driving shaft by unidirectional bearings. Each of the bearings locks the corresponding sprocket on the driving shaft only when the corresponding sprocket rotates in a predetermined direction. A flexible reciprocating element extends around an upper pulley and is fastened to the free ends of the swing arms at two ends thereof.

A Double-Sheaved Pulley Block from Kenchreai

Abstract: O NE of the most unusual small finds from the partially submerged \"temple\" at Kenchreai, the eastern port of Ancient Corinth, is a large wooden pulley or tackle block (Fig. 1, P1. 76, 1), complete with wooden pulley wheels, of the fourth or fifth century after Christ. It was discovered in an almost vertical position between the southeast return of the apse and Pile IX of the glass opus sectile panels.' This well-preserved ancient mechanical instrument, one of the few of its kind known, represents one of Heron of Alexandria's five mechanical powers of the ancient world: windlass, lever, pulley, wedge, and screw. As such, it adds to our knowledge of Roman technology and also gives us a glimpse into the Hellenistic technology which the Romans inherited and used so profitably. The block2 is 0.71 m. in length, 0.19 m. at its widest, and 0.15 m. thick. Basically, it is rectangular with a projection of wood, partially broken, at each end. The top projection is 0.18 m. long and the bottom one is 0.13 m. long. The original shape of either is unknown, for one cannot decide where the wood has been split, and

Long stroke pumping unit

Abstract: A long stroke pumping unit comprising a tower mounted on a base and a counterweight-polished rod system which bestrides a top wheel mounted on the top of said tower, employs an electric motor as its prime mover. The motor rotates in a fixed direction, and through a crank mechanism the rotation of electric motor is turned into a linear reciprocating movement which is in an approximately simple harmonic fashion, and then, by means consisting of fixed pulley blocks and a travelling pulley block assembly the stroke of said reciprocating movement is multiplied and transmitted to the counterweight-polished rod system. The stroke can be easily changed by changing the effective length of the crank, also, it can be selected within a great extent by changing the number of pulleys engaged in operation.

Non-slip pulley and belt drive

Abstract: In a belt and pulley system wherein motion is transferred between the two members, the belt is a metal belt having a pulley engaging face made of a relatively soft material and the pulley is one having a regular pattern of small hard protuberances, such as formed by knurling, on its belt engaging face which press into the soft metal of the belt to form permanent depressions arranged in a matching pattern which mesh with the protuberances to provide a positive slip-free motion transfer The belt and pulley drive may be used advantageously in a device such as an X-Y plotter for accurately positioning, with good repeatibility and fine resolution, an associated member driven in one coordinate direction by the metal belt driven in turn by the knurled pulley

Nonlinear Analysis of Cable Net Structures Suspended From Arches with Block and Tackle Suspension System, Taking into Account the Friction of the Pulleys

Abstract: A numerical procedure for the static analysis of arch-supported tensile structures with block and tackle suspension system is presented. The procedure, based on dynamic relaxation, is suitable for a structural analysis both in the prestressing process and in a final state under external loads. The friction between the pulley and its shaft is also taken into account in the analysis. After the introduction of the developed procedure, two structures are presented as examples. The analysis of a very simple structure validates the procedure, then the analysis of a more complex structure, an arch-supported cable net roof illustrates the stability and efficiency of the procedure.