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.

Dynamic Modeling of a Two-Axis, Parallel, H-Frame-Type XY Positioning System

Abstract: XY positioning is an important task in industrial applications. This paper addresses the dynamic modeling of a belt-driven, parallel-type XY positioning system constructed in the form of a capitalized H. The system uses one long timing belt to transmit the rotation of two stationary motors to end-effector motion. Due to less moved masses, the studied H-frame system is potentially capable of fast acceleration, and therefore, faster positioning than traditional stacked systems. The use of an elastic transmission element also causes the biggest disadvantage of the system, which is an uncertainty of end-effector position due to stretching in the belt. Thus, the objective of this paper is to develop a dynamic model that can capture the response of this system. Using Lagrange's method, an eighth-order lumped parameter dynamic model of the stage motion is derived. The effect of nonlinear friction in the pulleys and cart motion is added to the model. The response of the model was simulated in MATLAB Simulink, and the model prediction is compared with real data obtained from the developed system. The results show that the model can accurately predict the dynamics of the developed H-frame positioning system.

Orthopedic device for treatment of the back

Abstract: In an embodiment, an orthopedic device in the form of a lumbar support includes first and second elongate belt members, an anatomically shaped plate, and a closure system connecting the belt members to the plate. The closure system is arranged to move the belt members relative to the plate, and connects to the belt members via a flexible belt attachment which removably secures to the belt members. The closure system includes tensioning elements corresponding to the belt members, and a pulley system connecting to the tensioning elements. The closure system is slidably mounted to the plate and arranged to the belt members relative to the plate between opposed linear directions. The plate has various contours which provide pressure distribution over a lumbar region of a back. Anatomically shaped and resiliently formed handles secure to the tensioning elements and the belt members.

Vertical strip storage device

Abstract: A vertical strip storage device for bridging strip running interruptions in continuous strip production includes a supporting frame forming a looping tower. The continuous strip is looped around deflecting rollers mounted on upper and lower horizontal roller bridges. The roller bridges move synchronously and vertically, one above the other, toward and away from one another. The inherent weight of one roller bridge compensates for the inherent weight of the other roller bridge as a counterweight. A joint cable drive is used to move the roller bridges. One of the roller bridges is at the upward cable portion of the vertically deflected joint cable drive and the other roller bridge is at the downward cable portion of this vertically deflected joint cable drive. The joint cable drive includes pulley blocks supported in the upper region and in the lower region of the supporting frame. Each pulley block includes stationary rollers connected to the supporting frame and loose rollers connected to the respective roller bridges. A cable of each pulley block is guided to a cable drum such that when the cable drum rotates, the associated roller bridge moves.

Constant force compensation for power spring weight balance

Abstract: An apparatus for offsetting a constant force over a range of movement, includes a power spring or clock spring, defined by a length of resilient material wound in a spiral, the opposite ends of which are attached relative to one of the force and a fixed point, and to a pulley. The pulley is substantially coaxial with the spring and has a rounded outer contour defining a progressively varying slope proceeding axially along the pulley. A flexible cord wraps around the pulley and leads to the other of the force and the fixed point. The opposite (inner and outer) ends of the spring can be mounted such that the inner end of the spring is fixed relative to the fixed point and the outer end of the spring is attached to the pulley. The constant force can be the weight of a window sash, movable vertically in a frame. The rounded outer contour of the pulley defines a curve corresponding to an increase in torque of the spring with displacement, due to decrease in radius of the spring and decrease in active length of the spring with binding of inner wraps of the spiral.

Retightener for automatic safety belt roll-up devices

Abstract: Retightener for automatic safety belt roll-up devices with a power reservoir which can be triggered in the case of a crash and with an energy transducer which acts upon the belt shaft of the automatic winder after triggering the power reservoir, causing the automatic winder to perform a rotary retightening motion. A rotatable pulling means pulley is provided as energy transducer which can be coupled to the belt shaft. The pulling means of the pulley is in connection with the power reservoir and effects the coupling connection and a retightening motion of the belt shaft after triggering the power reservoir and after surmounting the holdback force of a holdback device, e.g. shear pins.