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"Pulleys"
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Pulleys in action
Explains how a pulley works and introduces the ways it is used in everyday life.
Book
Development trends in belt transmissions with V-belt
The continuous increase in the use of the transmissions with V-belt, the introduction of new materials for the production of belts and the development of new manufacturing techniques have become the reason for undertaking research works on the possibilities of increasing the load capacity and durability of belts as well as reducing their influence on the environment. It is important to know the latest mechanical and rheological characteristics of the belts in terms of their strength characteristics and fulfilment of the conditions for the correct operation of the transmission. The results of these works will make it possible to determine the scope of applicability of these belts in propulsion and transport technology as well as to develop new geometrical forms of pulleys and V-belts.
Journal Article
Comparison of 3T and 7T magnetic resonance imaging for direct visualization of finger flexor pulley rupture: an ex-vivo study
ObjectiveTo compare image quality and diagnostic performance of 3T and 7T magnetic resonance imaging (MRI) for direct depiction of finger flexor pulleys A2, A3 and A4 before and after artificial pulley rupture in an ex-vivo model using anatomic preparation as reference.Materials and Methods30 fingers from 10 human cadavers were examined at 3T and 7T before and after being subjected to iatrogenic pulley rupture. MRI protocols were comparable in duration, both lasting less than 22 min. Two experienced radiologists evaluated the MRIs. Image quality was graded according to a 4-point Likert scale. Anatomic preparation was used as gold standard.ResultsIn comparison, 7T versus 3T had a sensitivity and specificity for the detection of A2, A3 and A4 pulley lesions with 100% vs. 95%, respectively 98% vs. 100%. In the assessment of A3 pulley lesions sensitivity of 7T was superior to 3T MRI (100% vs. 83%), whereas specificity was lower (95% vs. 100%). Image quality assessed before and after iatrogenic rupture was comparable with 2.74 for 7T and 2.61 for 3T. Visualization of the A3 finger flexor pulley before rupture creation was significantly better for 7 T (p < 0.001). Interobserver variability showed substantial agreement at 3T (κ = 0.80) and almost perfect agreement at 7T (κ = 0.90).ConclusionMRI at 3T allows a comparable diagnostic performance to 7T for direct visualization and characterization of finger flexor pulleys before and after rupture, with superiority of 7T MRI in the visualization of the normal A3 pulley.
Journal Article
Geometric Specification of Non-Circular Pulleys Made with Various Additive Manufacturing Techniques
The paper presents the procedure of generating geometrical features on the contours of non-circular pulleys through the selection of materials and technological parameters for easy and efficient production of these parts. Based on the models designed in the computer aided design (CAD) system, several prototype non-standard pulleys were made, which were assessed for functional characteristics and correct operation of non-linear gears. The effect of additive technology on the geometric specification of non-circular pulleys was also assessed. The results showed that thanks to the use of additive methods, the need for costly manufacturing of such wheels with subtractive methods was eliminated. Additionally, it is not necessary to design specialized cutting tools or to use conventional or numerically controlled machine tools to manufacture these wheels. The test results showed that in case of selective laser sintering (SLS) the highest accuracy of mapping (0.01 mm) of geometrical features of the surface was obtained. This result is confirmed by the assessment of the morphology of the surface of the teeth of gears made with this technique, characterized by a uniform structure of the working surface of the wheel while maintaining a high tolerance of the outer profile of gear for selective laser sintering at the level of ±0.03 mm. Research has shown that most of the additive methods used to manufacture non-circular pulleys meet the required geometrical features and due to the short production time of these pulleys, these methods also facilitate quick verification of the designed pulley geometry.
Journal Article
Pulleys in my makerspace
Simple text describes the structure and uses of pulleys, and clear, step-by-step instructions show children how to make their own.
Book
An image processing-based method for determining the geometry transmission ratio of a continuously variable transmission gearbox
Nowadays, many applications based on image processing methods are deployed to bring convenience to use due to its outstanding superior features. This paper proposes an image processing-based method for determining the geometry transmission ratio of a continuously variable transmission (CVT) gearbox made up of a push-belt and two pulleys with synchronized width adjustments. The proposed method is demonstrated by many experiments on a real system consisting of 1 Logitech C992 Pro Webcam camera and 1 CVT gearbox. The experiments were conducted on more than 100 images. The experimental results show that the method’s error is between 6% and 8%, and the average processing time of 1 image is 0.07 seconds. This error depends on whether the camera position is parallel to the CVT gearbox’s cross-sectional plane or not. Furthermore, the reliability of the method is evaluated by the RMSE method up to 99%.
Journal Article
Simple machine experiments using seesaws, wheels, pulleys, and more : one hour or less science experiments
Describes experiments involving simple machines that follow the scientific method, and can be completed in an hour or less. Explore using levers to control motion and lift, and how the steepness of inclined planes affects the force needed to move something. Most experiments also include ideas for science fair projects.
Book
Design and analysis of an origami-based three-finger manipulator
This paper describes a new robotic manipulator with three fingers based on an origami twisted tower design. The design specifications, kinematic description, and results from the stiffness and durability tests for the selected origami design are presented. The robotic arm is made of a 10-layer twisted tower, actuated by four cables with pulleys driven by servo motors. Each finger is made of a smaller 11-layer tower and uses a single cable directly attached to a servo motor. The current hardware setup supports vision-based autonomous control and internet-based remote control in real time. For preliminary evaluation of the robot's object manipulation capabilities, arbitrary objects with varying weights, sizes, and shapes (i.e., a shuttlecock, an egg shell, a paper cub, and a cubic block) were selected and the rate of successful grasping and lifting for each object was measured. In addition, an experiment comparing a rigid gripper and the new origami-based manipulator revealed that the origami structure in the fingers absorbs the excessive force applied to the object through force distribution and structural deformation, demonstrating its potential applications for effective manipulation of fragile objects.
Journal Article