The Effect of Geometry Imperfections on the Performance of Multiple V-Belt Drives

1989 ◽  
Vol 111 (1) ◽  
pp. 153-159 ◽  
Author(s):  
G. Massouros
Keyword(s):  
Power Transmission ◽  
Mean Value ◽  
The Other ◽  
Belt Drive ◽  
Transmitted Power ◽  
Belt Drives ◽  
Analytical Results ◽  
Analytical Relations

It has been observed in practice, that the lifetime of a multiple V-belt drive is always less than the corresponding life of a single V-belt drive. This is due to an uneven contribution of all belts of the multiple drive to the power transmission owing to microerrors in the equality of the diameters and profiles of all grooves and of the lengths of all belts. These microerrors cause a distribution of the transmission ratios among the branches of the V-belt around a mean value which in turn results in an uneven loading of the belts and a reduction of their “life.” In the present work, analytical relations are obtained for the influence of the aforementioned errors on the elastic creep of the belts, on the transmitted power, and on the other characteristics of the belt drive. An experiment was made to verify the analytical results.

scholarly journals The power transmission stability and efficiency of V-belts

2016 ◽  
Vol 12 (1) ◽  
pp. 25-49
Author(s):  
László Kátai ◽  
Péter Szendrő ◽  
Péter Gárdonyi
Keyword(s):  
Internal Friction ◽  
Food Industry ◽  
Power Transmission ◽  
Angular Displacement ◽  
Hysteresis Loss ◽  
Damping Factor ◽  
Belt Drive ◽  
Agricultural Machinery ◽  
Plate Structure ◽  
Belt Drives

The V-belt drive is a rather popular, widely used form of power transmission in agricultural and food industry engineering. At the same time, its stability, the lifetime of V-belt is influenced by several environmental factors, namely in the food industry by the contamination affecting the belt sides, the ambient temperature, humidity and the occasionally aggressive (acidic, alkaline air, air saturated with gases, etc.) medium. In the case of agricultural machinery, the vibration caused by uncertainly oriented pulleys with bearing in different plate structures (often being shaken in the fields) as well as alignment adjustment inaccuracies jeopardize the reliability of the parameters of the drive. Furthermore, the efficiency is determined by several factors together: the slippage occurring during drive transmission, the hysteresis loss resulting from the external and internal friction occurring with the belt entering and exiting the pulley. Experimental equipment and calculation methods were developed to determine the dynamics of temperature increase generated by the belt and pulley relationship. The temperature generated in the V-belt was measured as a function of pretension, pulley diameter and bending frequency. The so-called damping factor characterizing the contact with the pulley (the external friction when entering and exiting the groove) and the hysteresis loss (inner friction) are also determined. On the basis of the damping factor (ζ ≈ 400 Ns/m2) of the V-belt involved in the experiments the other losses (Poth) occurring from the pulley—V-belt contact and internal friction may be estimated. The drive parameters may be optimized with the mathematical model describing the effect of the pulley diameter and belt frequency on the increase in temperature. A standardized calculation method as well as design factors valid for the properly adjusted drive and normal operating conditions determined through empirical and laboratory experiments are used for the sizing of V-belt drives. The lifetime of V-belt drives designed in this way, used in extreme conditions typical of agricultural machinery will not be appropriate and will not provide clear, predictable information for maintenance planning. In such cases the results of our own many lifetime tests conducted in the given circumstances can be safely relied on. The agricultural harvesting machines are large plate-body self-propelled structures on which most of the power supply of the (threshing, cleaning, moving, etc.) machine units handling the crop is realized via belt drives. The distance and angular displacement of the axes involved in the drive can vary within wide limits. The misalignment and angular displacement of the pulleys can be the result of installation instability — due to the plate structure — and the deformation of the plate structure occurring during the operation as well. V-belt drives operate satisfactorily under such conditions as well, however these faults are unfavourable in terms of belt lifetime and result in the reduction of drive efficiency. A further aim of our research is to examine through experiments the lifetime and efficiency of V-belts used in agricultural machines as a function of drive adjustment errors. According to the results of the measurements of the geometrical adjustment errors of V-belt drives performed in the field, the pulleys of agricultural equipment are not always positioned in the medium plane of the drive. In our experiments these data served as independent variables. Figure 1 shows the arrangement of a V-belt drive in a grain harvester with the laser pulley alignment measuring instrument installed as an accessory. In the case of many machine types in 80% of the tested drives three times the permissible error was measured, and because of off-road use, due to dynamic load these errors further increased as a result of the frame deformation. The results of both the belt bending testing and the geometrical adjustment testing of the drive offer great help in the design of belt drives. At the same time they can be the source of lifetime and efficiency forecasts.

Transmission Error Due to Resonance in Synchronous Belt Drive With Eccentric Pulley

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Masanori Kagotani ◽  
Hiroyuki Ueda
Keyword(s):  
Transverse Vibration ◽  
Rotation Frequency ◽  
Transmission Error ◽  
The Other ◽  
Belt Drive ◽  
Integer Multiple ◽  
Belt Drives ◽  
Eccentric Shaft ◽  
Synchronous Belt Drive ◽  
Frequency Variations

In synchronous belt drives, it is generally difficult to eliminate pulley eccentricity, because the pulley teeth and shaft hole are produced separately and the pulley is installed on an eccentric shaft. This eccentricity affects the accuracy of rotation transmission, so that the belt tension changes during a single rotation of the pulley. This in turn affects the occurrence of resonance in the spans. In the present study, the transmission error in a synchronous belt drive with an eccentric pulley in the absence of a transmitted load was experimentally investigated for the case in which the spans undergo first-mode transverse vibration due to resonance. The transmission error was found to have a component with a period equal to the span displacement, in addition to a component with a period of half the span displacement. During a single rotation of the pulley, the magnitude of the transmission error increased, and its frequency decreased, with decreasing belt tension. The transmission error exhibited the large value when two frequency conditions were satisfied: one was that the meshing frequency was within the range of span frequency variations due to the eccentricity, and the other was that the minimum span frequency was close to an integer multiple of the pulley rotation frequency. Even if both of these conditions occurred, if the range of span frequency variations due to the eccentricity was larger than 13 Hz, the transmission error could be eliminated by adjusting the belt tension, so that the average span frequency corresponded to the meshing frequency.

Influence of Installation Tension on Transmission Error Due to Resonance in a Synchronous Belt

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Masanori Kagotani ◽  
Hiroyuki Ueda
Keyword(s):  
Natural Frequency ◽  
Transmission Error ◽  
Experimental Results ◽  
The Other ◽  
Belt Drive ◽  
Analysis Method ◽  
Belt Drives ◽  
Mode Vibration ◽  
Synchronous Belt Drive ◽  
Good Agreement

In synchronous belt drives, a transmission error is generated due to resonance of the belt spanning the driving and driven pulleys when the transverse natural frequency of the belt approaches the meshing frequency of the belt and the pulley teeth. The behavior of this transmission error has been assumed to be dependent on the installation tension. In the present study, the influence of the installation tension on the transmission error in a synchronous belt drive under no transmitted load was experimentally investigated for the case in which first mode vibration due to resonance was induced in both the upper and lower spans. In addition, an analysis of the transmission error based on the experimental results was carried out. A method for reducing the error was also investigated. The transmission error contains two components: one with a period equal to the pitch of the pulley, and the other with a period of half the pulley pitch. Good agreement was found between the calculation and experimental results, thus confirming the validity of the analysis method. For a fixed pulley speed, the transmission error was largest when the installation tension was applied at a position where the displacement of the upper span was equal to that of the lower span. It was found that the transmission error could be reduced by pushing an idler lightly against the center of the span of the belt that was undergoing the largest displacement.

Transmission Error due to Resonance in Synchronous Belt Drive With Eccentric Pulley

2016 ◽  
Author(s):  
Masanori Kagotani ◽  
Hiroyuki Ueda
Keyword(s):  
Rotation Frequency ◽  
Transmission Error ◽  
Average Frequency ◽  
The Other ◽  
Belt Drive ◽  
Minimum Frequency ◽  
Integer Multiple ◽  
Belt Drives ◽  
Synchronous Belt Drive ◽  
Frequency Variations

In synchronous belt drives, it is generally difficult to eliminate pulley eccentricity, because the pulley teeth and shaft hole are produced separately. This eccentricity affects the accuracy of rotation transmission, so that the belt tension changes during a single rotation of the pulley. This in turn affects the occurrence of resonance in the spans. In the present study, the transmission error in a synchronous belt drive with an eccentric pulley in the absence of a transmitted load was experimentally investigated for the case in which the spans undergo first-mode transverse vibration due to resonance. The transmission error was found to have a component with a period equal to the displacement of the span, in addition to a component with a period of half the displacement of the span. During a single rotation of the pulley, the magnitude of the transmission error increased, and its frequency decreased, with decreasing belt tension. The transmission error exhibited the large value when two frequency conditions were satisfied: one was that the meshing frequency was within the range of span frequency variations due to the eccentricity, and the other was that the minimum frequency of the span was close to an integer multiple of the rotation frequency of the pulley. Even if both of these conditions occurred, if the range of span frequency variations due to the eccentricity was larger than 13 Hz, the transmission error could be eliminated by adjusting the belt tension so that the average frequency of the span corresponded to the meshing frequency.

Ideal Characteristics of a Variable Ratio Belt Drive

1988 ◽  
Vol 202 (1) ◽  
pp. 45-49
Author(s):  
S Bekircan
Keyword(s):  
Limiting Factors ◽  
Speed Ratio ◽  
Belt Drive ◽  
Variable Ratio ◽  
Transmitted Power ◽  
Fundamental Theory ◽  
Belt Drives ◽  
Compact Size ◽  
First Time ◽  
Ratio Range

A fundamental theory concerning the theoretical power-torque envelopes over the speed ratio range of a general variable ratio belt drive is presented, to the best of the author's knowledge, for the first time. This theory applies to both V and flat belt drives, and is independent of the detailed designs. The analysis is based on two limiting factors, namely the maximum tension and the tendency of the belt to slip bodily on one or both pulleys assuming that the centre distance and the belt length are constant. These above factors determine the power and torque envelopes. The most suitable envelopes for the design purpose of the variable ratio belt drive are those of compact size, maximum belt tension and relatively high transmitted power.

A Study on Noise in Synchronous Belt Drives (Experimental and Theoretical Analysis of Impact Sound)

2003 ◽  
Vol 125 (4) ◽  
pp. 773-778 ◽  
Author(s):  
Weiming Zhang ◽  
Tomio Koyama
Keyword(s):  
Theoretical Analysis ◽  
Transverse Vibration ◽  
Acoustic Energy ◽  
Generation Mechanism ◽  
The Other ◽  
Belt Drives ◽  
Analytical Results ◽  
Belt Width ◽  
The Impact

There are two kinds of noise in synchronous belt drives. One is steady sound caused by transverse vibration of the belt, and the other is impact sound radiating from the meshing point of the belt and pulley. In this study, a theoretical analysis is provided to prove the generation mechanism of the impact sound and discuss factors that influence the level of sound. Comparison between experimental and analytical results is carried out. It is concluded that the level of impact sound is in proportion to the belt width, and the acoustic energy of impact sound is in proportion to the cube of the belt width.

Influence of Installation Tension on Transmission Error due to Resonance in a Synchronous Belt

2014 ◽  
Author(s):  
Masanori Kagotani ◽  
Hiroyuki Ueda
Keyword(s):  
Natural Frequency ◽  
Transmission Error ◽  
Experimental Results ◽  
The Other ◽  
Belt Drive ◽  
Analysis Method ◽  
Belt Drives ◽  
Mode Vibration ◽  
Synchronous Belt Drive ◽  
Good Agreement

In synchronous belt drives, transmission error is generated due to resonance of the belt spanning the driving and driven pulleys when the transverse natural frequency of the belt approaches the meshing frequency of the belt and the pulley teeth. The behavior of the transmission error caused by resonance has been assumed to be dependent on the installation tension. In the present study, the influence of installation tension on the transmission error in a synchronous belt drive was experimentally investigated for a case in which first mode vibration due to resonance was induced in both the upper and lower spans. In addition, an analysis of the transmission error based on the experimental results was carried out. A transmission error contains two components: one with a period equal to the pitch of the pulley, and the other with a period of half the pulley pitch. Good agreement was found between the calculation and experimental results, thus confirming the validity of the analysis method. For a fixed pulley speed, the transmission error was largest when the installation tension was applied at a position where the displacement of the upper span was equal to that of the lower span. When the installation tension was varied and the pulley speed was adjusted so that the belt experienced resonance, the transmission error decreased with an increase in installation tension.

Piece-Wise Linear Dynamic Systems With One-Way Clutches

2004 ◽  
Vol 127 (5) ◽  
pp. 475-482 ◽  
Author(s):  
Eric M. Mockensturm ◽  
Raghavan Balaji
Keyword(s):  
Dynamic Systems ◽  
Power Transmission ◽  
Piezoelectric Actuators ◽  
Belt Drive ◽  
Linear Dynamic Systems ◽  
System Parameters ◽  
Belt Drives ◽  
Linear Dynamic ◽  
Serpentine Belt ◽  
Simple Systems

One-way clutches and clutch bearings are being used in a wide variety of dynamic systems. Motivated by their recent use as ratchets in piezoelectric actuators and decoupling devices in serpentine belt drives, a method of analysis of systems containing one-way clutches is presented. Two simple systems are analyzed. The goal of the first is the power transmission which would be of concern in an actuator. The goal of the second is decoupling large inertia elements to reduce loads in an oscillating system, the objective of the clutch in a serpentine belt drive. Results show how system parameters can be tuned to meet the desired performance of these piece-wise linear systems.

scholarly journals The laboratory findings and different COVID-19 severities: a systematic review and meta-analysis

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Erfan Kazemi ◽  
Reihane Soldoozi Nejat ◽  
Fatemeh Ashkan ◽  
Hossein Sheibani
Keyword(s):  
Systematic Review ◽  
Platelet Count ◽  
Critically Ill ◽  
Critically Ill Patients ◽  
Lymphocyte Count ◽  
Leukocyte Count ◽  
Mean Value ◽  
The Other ◽  
Invasive Ventilation ◽  
Laboratory Findings

Abstract Background Abnormal laboratory findings are common in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The aim of this systematic review was to investigate the effect of the level of some laboratory factors (C-reactive protein (CRP), creatinine, leukocyte count, hemoglobin, and platelet count) on the severity and outcome of coronavirus disease 2019 (COVID-19). Methods We searched PubMed, Web of Science, Scopus, and Google Scholar. We collected the articles published before May 26, 2020. We gathered the laboratory factors in groups of patients with COVID-19, and studied the relation between level of these factors with severity and outcome of the disease. Results Mean CRP level, creatinine, hemoglobin, and the leukocytes count in the critically ill patients were significantly higher than those of the other groups (non-critical patients); mean CRP = 54.81 mg/l, mean creatinine = 86.82 μmol/l, mean hemoglobin = 144.05 g/l, and mean leukocyte count = 7.41 × 109. The lymphocyte count was higher in patients with mild/moderate disease (mean: 1.32 × 109) and in the invasive ventilation group (mean value of 0.72 × 109), but it was considerably lower than those of the other two groups. The results showed that the platelet count was higher in critically ill patients (mean value of 205.96 × 109). However, the amount was lower in the invasive ventilation group compared with the other groups (mean level = 185.67 × 109). Conclusion With increasing disease severity, the leukocyte count and the level of CRP increase significantly and the lymphocyte count decreases. There seems to be a significant relation between platelet level, hemoglobin, and creatinine level with severity of the disease. However, more studies are required to confirm this.

scholarly journals Hydrometeor and latent heat profiles of tropical cyclones Conson, Ivan and Catarina using PR/TRMM data

2010 ◽  
Vol 25 (2) ◽  
pp. 156-174 ◽  
Author(s):  
Marcelo Barbio Rosa ◽  
Augusto Pereira Filho ◽  
Prakki Satyamurty
Keyword(s):  
Water Content ◽  
Latent Heat ◽  
High Water ◽  
Mean Value ◽  
The Other ◽  
High Water Content ◽  
Hurricane Ivan ◽  
Two Systems ◽  
Low Levels ◽  
Ice Content

ABSTRACT Microphysical and thermodynamical features of two tropical systems, namely Hurricane Ivan and Typhoon Conson, and one sub-tropical, Catarina, have been analyzed based on space-born radar PR measurements available on the TRMM satellite. The procedure to classify the reflectivity profiles followed the Heymsfield et al (2000) and Steiner et al (1995) methodologies. The water and ice content have been calculated using a relationship obtained with data of the surface SPOL radar and PR in Rondonia State in Brazil. The diabatic heating rate due to latent heat release has been estimated using the methodology developed by Tao et al (1990). A more detailed analysis has been performed for Hurricane Catarina, the first of its kind in South Atlantic. High water content mean value has been found in Conson and Ivan at low levels and close to their centers. Results indicate that hurricane Catarina was shallower than the other two systems, with less water and the water was concentrated closer to its center. The mean ice content in Catarina was about 0.05 g kg-1 while in Conson it was 0.06 g kg-1 and in Ivan 0.08 g kg-1. Conson and Ivan had water content up to 0.3 g kg-1 above the 0ºC layer, while Catarina had less than 0.15 g kg-1. The latent heat released by Catarina showed to be very similar to the other two systems, except in the regions closer to the center.

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