Clutch Characteristics Research Articles

Engagement/Disengagement Characteristics of Pull-Type Diaphragm Spring Clutch for Heavy-Duty Commercial Vehicles

Considering that the clutch cover assembly and driven disc assembly show common effect on the engagement/disengagement characteristics of the pull-type diaphragm spring clutches for heavy-duty commercial vehicles, the diaphragm spring, cushion plate, and friction plate, are thoroughly analyzed in this paper. The A-L method and the micro-element method are used to analyze the mechanical properties of diaphragm spring and cushion plate, respectively. The mechanical characteristics are obtained via numerical simulation, and the deformation and load mechanical characteristics of the cushion plate are verified by experimental tests. According to the relationship between the pressure plate temperature and the friction coefficient of the friction plate, the influence of the change of the friction coefficient on the transmission torque characteristics of the clutch is analyzed. In view of the torque fluctuation in the process of engagement/disengagement, the mathematical model of torsional characteristics is established with consideration of the torsional characteristics of torsional damper. Modeling and simulation of the handling characteristics are carried out to evaluate the influence of the boosting characteristics of the hydraulic operated pneumatic booster on the clutch pedal operating force separation characteristics. Specific tests are also conducted, and the effectiveness of the established models is verified.

Research on high-speed drag torque characteristics of wet clutches based on mechanism and data-driven approach

Research on high-speed drag torque characteristics of wet clutches based on mechanism and data-driven approach

Dynamics modeling and analysis of the multistage planetary gear set-bearing-rotor-clutch coupling system considering the tooth impacts of clutches

Previous studies about the dynamics of the planetary gear system are mainly focused on transmission systems with a fixed transmission ratio, whereas the dynamic studies of vehicle automatic transmission with multiple transmission ratios achieved by engaging different clutches were seldom investigated. This is largely due to the lack of modeling strategies for the stochastic tooth impacts of detached clutches on the dynamics of transmission systems. Ignoring the stochastic tooth impacts on the system’s performance will result in inaccurate analysis that may overestimate the machine’s service performance. In this paper, an original dynamic model of the multistage planetary gear set-bearing-rotor-clutch coupling system with multi-shift and multi-speed transmission is established considering the tooth impacts of detached clutches. An embedded measurement method is developed to measure the in-situ torsional vibration responses of rotating parts under various shift and speed conditions, which are directly compared to simulated responses of the proposed model for validation purposes. Finally, the effects of the rotating speed and clutch’s tooth backlash on the random tooth impact characteristics of clutches are revealed. The modeling strategy of this work provides a more accurate and realistic simulation of automatic transmission’s dynamic performance and supplies theoretical guidance for the strength evaluation and early fatigue failure analysis between mating teeth of clutches.

Analysis on Effects of Material Parameters on Thermoelastic Instability of Separate Plate in Wet Clutch

Abstract The working characteristics of wet clutches have an important impact on the safety performance of vehicles. In order to obtain the thermoelastic instability characteristics of wet clutch separate plate, a finite element modeling method is proposed. The temperature field calculation model of separate plate and its thermo-hydro-mechanical coupling relationship are constructed. The distribution law of high-temperature hot spots on the surface of separate plate is obtained and the thermoelastic instability mechanism is revealed. Effectiveness of the simulation model is verified by road test, and surface topography of separate plate is observed by scanning electron microscope. A thermoelastic instability calculation model considering different material parameters is established. The temperature field distribution law is reviewed under different elastic moduli, specific heat capacities, thermal conductivities, and thermal expansion coefficients. Results show that increasing the specific heat capacity and thermal conductivity of the separate plate, decreasing the elastic modulus and thermal expansion coefficient can improve the stability of the system. The thermal conductivity and thermal expansion coefficient have important effects on the thermoelastic instability. The specific heat capacity has a certain effect, and the elastic modulus’ effect is the least. The research results of this paper can provide theoretical support for optimizing the structure of wet clutch and improving the stability of the system.

Расчет кривой сцепления для проектирования противоюзовых и противобоксовочных систем

Purpose: Creation of mathematical apparatus for calculating clutch curve in designing of anti-skid and anti-slippage devices. It is necessary to obtain formula suitable for calculating the dependence of clutch coefficient from absolute and relative slippage speeds of wheelsets along rails and from electric rolling stock (ERS) speed. Methods: Result analysis of trials for various ERS types according to data from open sources and to clutch characteristics obtained as a result of these trials with the use of mathematical statistics methods. Results: as a result of the work, it has been managed to represent the dependence for calculating clutch coefficient in the form of two function “joining”. Practical significance lies in the possibility to use the work results at designing anti-skid/anti-slippage device UPZ-M.

Individual egg production of Hy-Line Brown hens during the early laying phase in response to dietary CP levels

The aim of this study was to investigate the effects of gradually increased dietary CP level on the dynamics of individual egg production of laying hens from 18 to 54 weeks of age. Forty Hy-Line Brown hens were divided into five treatments of eight replicates each and were fed diets formulated to have five different CP concentrations: 14, 15, 16, 17, and 18% CP with the same energy content. For each experimental diet, the contents of lysine, methionine + cysteine, threonine, and tryptophan were maintained at minimum requirement concentrations by supplying synthetic amino acids. Clutch characteristics were recorded (e.g., number, size, patterns, egg weight, etc.) and individual egg production curves were modeled according to Grossman and Koops (2001). Clutch size was defined as the unstopped length of individual egg production on a daily basis. BWs were also recorded every week to account for changes in BW during the experimental period. Three hens were excluded from the statistical analyses as their laying patterns were very inconsistent. Four clutch patterns with data weighted on a weekly basis were identified. Heavier hens tended to lay more regular clutch patterns when compared to their lighter counterparts within the same treatment. In contrast, irregular clutch patterns (too many pauses between clutches) were more common in hens fed low CP diets (≤16%). This could be explained by imbalances in amino acids supply according to their theoretical requirements and adverse effects caused by amino acids interactions. Low CP diets were able to maintain egg production and mean clutch size up to 54 weeks of age. The maximum clutch size and the modeled proportion of maximum production for the increasing phase (k1) displayed a linear response to the graded addition of CP content to the diet. No differences were detected among treatments for the age at the beginning of the maximum clutch (22.6 ± 2.82 weeks). Egg weight displayed a quadratic response that was maximized when hens were fed 17% CP in the diet. Our approach appears to be promising for ranking individual laying hens based on their clutch performance to evaluate both CP and amino acids adequacy of diets.

Educational and laboratory installation for the study of the characteristics of friction clutches

The article presents the stages of designing an educational and laboratory installation for testing the friction clutch of a transport vehicle. The created installation has small mass-dimensional dimensions (desktop), low cost and allows students of transport directions to study with the use of components and elements of clutch couplings used in cars, the device and processes occurring in them. The methodology of laboratory work using the manufactured stand is given. Keywords: сar clutch, torsional vibration damper, torque

The courtship call of <i>Bokermannohyla ibitiguara</i> (Anura: Hylidae) and details of its mating behavior

Complex courtships have been described for neotropical frogs, but detailed quantifications of calls emitted during this behavior are still rare. Herein, we describe the courtship call of Bokermannohyla ibitiguara, a gladiator tree frog from the Brazilian Cerrado, as well as the female behavior during courtship, and the clutch characteristics. Moreover, we statistically compare the acoustic parameters of the advertisement and courtship calls. We observed that the female also touches the male during courtship and that the courtship call is overall similar to the long note of the advertisement call. However, we uncovered significant differences in frequencies and pulses between these two call types emitted by the same male. This ability to modify call parameters is consistent with previous results in aggressive contexts and reinforces sexual selection as a strong mechanism shaping call variation in this species. This is the third courtship call described for the genus and we emphasize that the description of rare behaviors, even in artificial conditions, is important to advance the field of behavioral ecology across taxa.

The evolution of reproductive strategies in turtles.

Optimal egg size theory assumes that changes in the egg and clutch are driven by selection, resulting in adjustments for the largest possible production of offspring with the highest fitness. Evidence supports the idea that large-bodied turtles tend to produce larger clutches with small and round eggs, while smaller species produce small clutches with large and elongated eggs. Our goals were to investigate whether egg and clutch size follow the predictions of egg size theory, if there are convergent reproductive strategies, and identify ecological factors that influence clutch and egg traits across all clades of living turtles. Using phylogenetic methods, we tested the covariance among reproductive traits, if they are convergent among different turtle lineages, and which ecological factors influence these traits. We found that both egg shape and size inversely correlate with clutch size, although with different evolutionary rates, following the predictions of the egg size theory. We also present compelling evidence for convergence among different turtle clades, over at least two reproductive strategies. Furthermore, climatic zone is the only ecological predictor to influence both egg size and fecundity, while diet only influences egg size. We conclude that egg and clutch traits in Testudines evolved independently several times across non-directly related clades that converged to similar reproductive strategies. Egg and clutch characteristics follow the trade-offs predicted by egg size theory and are influenced by ecological factors. Climatic zone and diet play an important role in the distribution of reproductive characteristics among turtles.

Louisiana Black-bellied Whistling-Duck clutch characteristics in the presence of conspecific and interspecific brood parasitism

Black-bellied Whistling-Ducks (<em>Dendrocygna autumnalis</em>; Whistling-Duck) are undergoing a rapid range expansion northward and now breed throughout the Southeastern United States. As a facultative cavity-nesting species, they have the potential to compete with Wood Ducks (<em>Aix sponsa</em>) and Hooded Mergansers (<em>Lophodytes cucullatus</em>) for nest sites. Little is known about Whistling-Duck breeding biology, and estimates of clutch characteristics and rates of conspecific and interspecific brood parasitism (CBP and IBP, respectively) are lacking. We monitored Whistling-Duck nests in Louisiana to describe nesting chronology, clutch size of parasitized and unparasitized (normal) nests, and hatchability (i.e., the portion of eggs that hatched) for clutches of different sizes and types. We monitored a total of 558 nest boxes between 2020–2021 and determined the presence of brood parasitism for 231 Whistling-Duck nests. CBP was detected in 73 (31.6%) nests, and IBP was observed in 51 (22.1%) nests parasitized by Wood Ducks, two (0.9%) nests parasitized by Hooded Mergansers, and one nest contained eggs from all three species. Normal clutches were smaller (15.4 ± 4.4 eggs) than CBP clutches (26.1 ± 8.8 eggs) and mixed clutches (22.2 ± 5.3 eggs; clutches containing Wood Duck or Hooded Merganser eggs; all pairwise P < 0.0001). However, within clutch repeatability, estimates for egg morphology data (i.e., length, width, and mass) were low (< 0.40) for normal clutches, suggesting CBP went undetected. Of 180 fated nests used to determine hatchability, 66 (36.7%) were successful, 49 (27.2%) were abandoned, 64 (35.6%) were depredated, and one (0.6%) was nonviable. Considering successful nests, hatchability was high for all clutch size bins ranging from 67.4% (41–45 eggs) to 81.6% (11–15 eggs). Our study is the first to document Whistling-Ducks successfully hatching mixed-species broods, and such high productivity could be contributing to Whistling-Duck range expansion.

Analytical modeling and dimensionless characteristics of open wet clutches in consideration of gravity

Wet clutches are widely used in power transmission, but lack of the fact of an energy loss in open state condition. The flow conditions in the fluid flow of an open wet clutches are analyzed by analytical means. The requisite simplifications that result in an analytically integrateable solution are stated in detail. Special emphasis is put on the role of gravitation in the equations of fluid motion. This force component leads to a slightly earlier aeration than stated in earlier conditions. The simplifications and the resultant solutions are considered by means of dimensionless quantities. Despite the actual geometric parameters the drag torque can be described as zeta_{mathrm{m}}=pi/mathrm{Re}_{mathrm{l}}. An additional aeration condition is introduced, which is based on the back flow of the radial velocity. This quantity can be described as non-dimensional volumetric flow rate Q^{*}. With these equations at hand the theoretical considerations are transferred to an evaluation with grooves, where a backward curved groove appears as beneficial for further investigations.

Study on the groove area effects on the friction-wear properties of a Cu-based wet clutch

The numerical model is proposed to investigate the micro-contact characteristics of asperity summits; moreover, the influence of groove area on the friction-wear properties of a Cu-based wet clutch is explored by the bench test. With the increase of rotating speed or applied pressure, the differences of the thermodynamic characteristics of clutches with different groove areas gradually narrow. However, reducing the groove area can reduce the wear of friction disc but increase the carbon black. The thermal environment is the worst in the middle of clutch, where friction components are most likely to fail. Therefore, the groove area should be designed based on the axial position of friction discs to optimize the friction-increasing and wear-reducing performance of the clutch.

Adaptive gearshift control of wet dual clutch transmission based on extended state observer and H∞ robust control

The clutch characteristics of dual clutch transmission (DCT) will change as the service time increases, which will lead to the deterioration of gearshift performance. To reduce the influence of the change in clutch characteristics on the gearshift performance, an adaptive gearshift control method based on the extended state observer and H∞ robust control is proposed. First, the gearshift problem of the DCT is transformed into the reference trajectory tracking problem, and the gearshift reference trajectory is designed using the minimum principle. The uncertain term related to the change in clutch characteristics in the DCT gearshift dynamic model is defined, and an extended state observer is designed to estimate the uncertain term. On this basis, the gearshift controller is designed using the backstepping method, and H∞ robust control is introduced to further improve the adaptation effect of the controller, then the adaptive control laws of the clutch pressure and engine torque are obtained. Finally, the adaptation effect of the proposed method was verified by both simulation and experiment. The results show that the proposed adaptive gearshift control method can effectively avoid the gearshift delay caused by the change in clutch characteristics, and the gearshift jerk in the simulation and experiment is reduced by 55.01% and 34.8%, respectively.

Comparison of spring and summer clutches of Great Crested Grebes (Podiceps cristatus)

The intensively farmed fishponds of the Třeboň Basin in South Bohemia, Czech Republic host a substantial number Great Crested Grebe (Podiceps cristatus) pairs that nest later than the expected spring season and instead in summer, which may be associated with fishpond farming. A two-factor nested ANOVA of Great Crested Grebe egg and clutch characteristics showed no differences between spring (May-June) and summer (July - August) seasonal clutches. High egg total volume in spring nests was significantly related to both decreasing distance between nests and decreasing number of nests on the fishpond. The increase of total egg volume in summer nests was significantly related to the distance to the edge of littoral vegetation. There is no substantial difference between spring and summer egg characteristics, but total egg volume in spring nests is dependent on other characteristics that those in summer nests.

Non-dimensional characteristics of open wet clutches for advanced drag torque and aeration predictions

The remaining torque of disengaged wet clutches is a major source of energy loss and, therefore, an objective of current research. The present contribution describes the necessary simplifications to obtain an analytical solution of the governing equations by means of an order-of-magnitude analysis. The obtained results are brought to a dimensionless frame of reference, where formerly unknown simple dependencies of the drag torque and the aeration onset have been uncovered. The dimensionless description serves as promising a means to achieve a quantitative comparison of experimental data. Additionally, a new modelling concept for grooves is introduced, which is based on the hydraulic-diameter concept. The combination of either approach offers a robust prediction method for drag torque and aeration onset.

Perfluorooctanoic acid exposure impact a trade-off between self-maintenance and reproduction in lizards (Eremias argus) in a gender-dependent manner

The trade-off between self-maintenance and reproduction has been explored wildly in reptiles. However, the effects of exogenous pollutants on the life history traits of reptiles have not been paid attention to. In the current study, lizards (Eremias argus), living in the soil polluted by perfluorooctanoic acid (PFOA) were selected as the main focus. Bodyweight, survival rate, clutch characteristics and biochemical analysis (immune response, lipid accumulation, sex steroid secretion, antioxidant level, and metabolomics) were investigated and the results revealed that lizards’ life-history trade-offs are gender-dependent: females were more inclined to choose a “Conservative” life-history strategy. After 60 days of exposure to PFOA, larger body weight, higher survival rate, stronger immune response, and lighter egg mass in females suggested that their trade-offs are more biased towards self-maintenance. Whereas, the “Risk” strategy would more popular among males: reduced body weight and survival rate, and suffering from oxidative damage indicated that males made little investment in self-maintenance.

The wear characteristics of wet clutches in the DSG vehicle in a 10km driving cycle

In order to investigate the wear characteristics of wet clutches in the DSG vehicle during shift process, this paper presents a dynamic analytical model and an experimental test of wet friction pair for simulation and analysis. A detailed dynamic model is established firstly to calculate the dynamic load of the clutches during the shift process. The wet friction pair experiment is conducted to explore the wear behaviours under different conditions. Then, the wear coefficient is deduced. The experimental results indicate that, when the temperature is constant, the slipping speed has little influence on the wear coefficient, while the contact pressure is on the contrary. Then, an empirical formula is obtained to describe the relationship between the wear coefficient and the contact pressure. Based on the simulation results, the wear amount of the clutches fixed on the input shaft is about 0.8mg, while for clutches on the middle shaft, it is only 0.2mg within a 10km driving cycle.

Correlated evolution of nest and egg characteristics in birds

Correlational selection is defined as selection for adaptive character combinations, and it therefore favours combinations of coevolved traits via phenotypic integration. Whereas the evolution of avian nest-building and egg-laying characteristics are well understood, their correlated dynamics remain overlooked. Here, we examined patterns of correlated evolution between nest, egg and clutch characteristics in 855 species of birds from 90 families, representing nearly 9% and 33% of avian species- and family-level diversity. We show that the ancestral state of birds’ nests was semi-open with nest sites having since become progressively more open over time. Furthermore, nest characteristics appear to have influenced egg-laying patterns in that while semi-open nests with variable clutch sizes were probably ancestral, clutch sizes have declined over evolutionary time in both open and closed nests. Ancestrally, avian eggs were also large, heavy and either elliptic or round, and there have been high transition rates from elliptic to round eggs in open nests and vice versa in closed nests. Ancestrally, both unpigmented (white) and pigmented (blue–brown) eggs were laid in open nests, although blue–brown eggs have transitioned more to white over time in open and closed nests, independently. We conclude that there has been a remarkable level of correlated evolution between the nest and egg characteristics of birds, which supports scenarios of correlational selection on both of these extended avian phenotypes.

Effects of L-Glufosinate-ammonium and temperature on reproduction controlled by neuroendocrine system in lizard (Eremias argus)

In the context of global warming, an important issue is that many pesticides become more toxic, putting non-target organisms at higher risk of pesticide exposure. Eremias argus (a native Chinese lizard) was selected as animal model in this study. As a kind of poikilothermic vertebrate, E.argus is sensitive to temperature change. The experimental design [(with or without L-Glufosinate-ammonium (L-GLA) pollution × two temperatures (25 and 30 °C)] was used in this study for 90 days to identify the chronic effects of the pesticide–temperature interaction on the lizards’ neuroendocrine-regulated reproduction. Survival rate, body weight, clutch characteristics, testicular histopathology, the content of neurotransmitters and related enzyme activity, the level of sex steroid, the expression of Heat shock protein 70 (HSP70), antioxidant system, the accumulation and degradation of L-GLA were examined. Results showed that L-GLA disrupt reproduction of lizards through hypothalamus-pituitary-gonad (HPG) axis. In addition, temperature can not only change the environmental behavior of pesticides, but also alter the physiological characteristics of lizards. Thus, our results emphasized that temperature is an essential abiotic factor that should not be overlooked in ecotoxicological studies.

Protoporphyrin‐based eggshell pigmentation predicts hatching success and offspring sex ratio in the barn swallow

Inter‐ and intraspecific variation in eggshell colouration has long fascinated evolutionary biologists. Among species, such variation may accomplish different functions, the most obvious of which is camouflage and background matching. Within species, it has been proposed that inter‐female variation in eggshell pigmentation patterns can reflect egg, maternal or paternal traits and hence may provide cues to conspecifics about egg, maternal or paternal phenotypic quality. However, the relationship between protoporphyrin‐based eggshell pigmentation and egg or maternal/paternal traits appears to be highly variable among species. We investigated patterns of intraspecific variation in Eurasian barn swallowHirundo r. rusticaprotoporphyrin‐based eggshell pigmentation, and analysed its association with egg and clutch characteristics, maternal/paternal phenotypic traits and parental feeding effort. Eggshell pigmentation pattern significantly varied between breeding colonies, was significantly repeatable in first clutches laid by the same females in different years (intraclass correlation coefficient ranging between 0.56 and 0.63), but it was not significantly associated with egg traits, such as position in the laying sequence, egg mass, yolk testosterone concentration and antioxidant capacity. It was weakly or non‐significantly associated with female and male traits (sexual ornaments), but females laying darker (higher pigment intensity) first clutches had higher hatching success, suggesting that eggshell pigment intensity may predict fitness. Male nestling feeding effort was not predicted by eggshell pigmentation. In addition, females with darker breast plumage colouration (a melanin‐based trait related to fitness) laid highly protoporphyrin‐covered eggs, suggesting the presence of a previously unappreciated link between protoporphyrin biosynthesis and plumage melanisation. Moreover, the proportion of male offspring increased in clutches originating from highly protoporphyrin‐covered eggs, suggesting that parents could acquire visual cues about their future brood sex composition before egg hatching. Our results support the idea that intraspecific signalling via eggshell pigmentation is a species‐specific rather than a general feature of avian taxa.