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.

Nonlinear Coupled Vibration Response of Serpentine Belt Drive Systems

Abstract: This theoretical and experimental study identifies a key nonlinear mechanism that promotes strongly coupled dynamics of serpentine belt drive systems. Attention is focused on a prototypical three-pulley system that contains the essential features of automotive serpentine drives having automatic (spring-loaded) tensioners. A theoretical model is presented that describes pulley and tensioner arm rotations, and longitudinal and transverse belt vibration response. A recent investigation demonstrates that infinitesimal belt stretching creates a linear mechanism that couples transverse belt vibration to tensioner arm rotation. Here, it is further demonstrated that finite belt stretching creates a nonlinear mechanism that may lead to strong coupling between pulley/tensioner arm rotation and transverse belt vibration, in the presence of an internal resonance. Theoretical and experimental results confirm the existence of this nonlinear coupling mechanism. In particular, it is shown that very large transverse belt vibrations can result from small resonant torque pulses applied to the crankshaft or accessory pulleys. These large amplitude transverse vibrations are particularly sensitive to seemingly small changes in the rotational mode characteristics.

A mechanical study of six digital pulley reconstruction techniques: Part I. Mechanical effectiveness.

Abstract: A laboratory study on fresh-frozen human cadaver limbs compared six types of flexor tendon pulley reconstruction in the fingers. The reconstructions used were those described by (1) Bunnell, (2) Karev, (3) Weilby, and (4) Lister, and two types developed by us that have not been previously described. The pulleys were studied in specific configurations to determine their effectiveness in transforming tendon excursion into finger flexion. In each finger, comparison was made between the amount of tendon excursion required for full flexion with an intact pulley system versus the various types of reconstructed pulleys. The ratio of these two values was defined as the mechanical effectiveness of the pulley reconstruction. The Karev reconstruction was most effective at 108.2%, which was significantly different from the other five reconstructions ( p

Neural and mechanical factors in eye control.

Abstract: Soft tissue "pulleys" in the orbit alter the paths of the eye muscles in a way that may simplify the brain's work in implementing Listing's law, i.e., in holding ocular torsion at zero. But Listing's law does not apply to some oculomotor systems, such as the vestibuloocular reflex (VOR), which shows a different kinematic pattern. To explain this different pattern, some authors have assumed that the pulleys must adopt a different configuration, retracting along their muscles when the eye switches from Listing's law to VOR mode. The proposed retraction has not so far been observed, although the pulleys do move in other ways. We show that the hypothetical retraction of the pulleys would not in fact explain the full kinematic pattern seen in the VOR. But this pattern can be explained entirely on the basis of pulley positions and motions that have actually been observed. If one takes into account the neural processing within the VOR, specifically the fact that the reflex is weak in the torsional dimension, then a single mode of pulley action can serve both vestibuloocular kinematics and Listing's law.

Belt grinder attachment for powered rotary tools

Abstract: A belt grinder attachment for powered rotary tools mounts an abrasive belt for movement transverse to the axis of the tool for ease of alignment of the belt on a work piece. The attachment body member can either be threaded onto the tool housing or be clamped thereon. An arm extends from the body member and is radially adjustable for tensioning the belt. A driven pulley assembly is mounted on the free end of the arm and provides for the belt to run either directly on opposite sides of the arm or to one side only. The normal chuck of the tool is replaced by a drive pulley and the belt extends around both the drive and driven pulleys.

Dual-function treading exerciser

Abstract: A dual-function treading exerciser includes a treading platform, an upright frame, and a movable handle assembly. The frame includes an upright frame body and two fixed handles connected fixedly to an upper portion of the frame body. The movable handle assembly includes two pulling devices and a rotary shaft journalled on the frame. Each pulling device includes a housing with a receiving chamber, a pulley disposed rotatably in the chamber, a pull cord wound on the pulley, a handgrip fastened to an end of the cord and movable rearwardly to unwind the cord from the pulley, and a biasing unit for biasing the cord to wind around the pulley when the cord is pulled rearwardly and is subsequently released.