Locomotive Adhesion Research Articles

Planning of a numerical experiment in order to determine the effect of operating factors on the traction-adhesion properties of locomotives

The paper reviews the results of an evaluation of the influence of the operating factors on traction-adhesive prop-er-ties of a locomotive. Planning of an xperiment was performed for two locomotives ?freight locomotive 2TE116 and shunting locomotive TEM103. The input for performing the numerical experiment was variation of 6 factors: the change in the wheel diameter of the first wheelset due to wear, the change in the mass of the locomotive as a result of the change in the amount of the fuel as well as the wheel rims wear, the impact of the friction damper in the primary suspension, change in the primary and secondary suspension stiffness due to operation. Regression equati-ons were obtained in code and natural form, which describe the effect of operating factors on the coeffi-cient of utilization of the locomotive adhesion mass.

Molecular insights into the powerful mucus-based adhesion of limpets (Patella vulgata L.).

Limpets (Patella vulgata L.) are renowned for their powerful attachments to rocks on wave-swept seashores. Unlike adult barnacles and mussels, limpets do not adhere permanently; instead, they repeatedly transition between long-term adhesion and locomotive adhesion depending on the tide. Recent studies on the adhesive secretions (bio-adhesives) of marine invertebrates have expanded our knowledge on the composition and function of temporary and permanent bio-adhesives. In comparison, our understanding of the limpets' transitory adhesion remains limited. In this study, we demonstrate that suction is not the primary attachment mechanism in P. vulgata; rather, they secrete specialized pedal mucus for glue-like adhesion. Through combined transcriptomics and proteomics, we identified 171 protein sequences from the pedal mucus. Several of these proteins contain conserved domains found in temporary bio-adhesives from sea stars, sea urchins, marine flatworms and sea anemones. Many of these proteins share homology with fibrous gel-forming glycoproteins, including fibrillin, hemolectin and SCO-spondin. Moreover, proteins with potential protein- and glycan-degrading domains could have an immune defence role or assist degrading adhesive mucus to facilitate the transition from stationary to locomotive states. We also discovered glycosylation patterns unique to the pedal mucus, indicating that specific sugars may be involved in transitory adhesion. Our findings elucidate the mechanisms underlying P. vulgata adhesion and provide opportunities for future studies on bio-adhesives that form strong attachments and resist degradation until necessary for locomotion.

Train energy simulation with locomotive adhesion model

Railway train energy simulation is an important and popular research topic. Locomotive traction force simulations are a fundamental part of such research. Conventional energy calculation models are not able to consider locomotive wheel–rail adhesions, traction adhesion control, and locomotive dynamics. This paper has developed two models to fill this research gap. The first model uses a 2D locomotive model with 27 degrees of freedom and a simplified wheel–rail contact model. The second model uses a 3D locomotive model with 54 degrees of freedom and a fully detailed wheel–rail contact model. Both models were integrated into a longitudinal train dynamics model with the consideration of locomotive adhesion control. Energy consumption simulations using a conventional model (1D model) and the two new models (2D and 3D models) were conducted and compared. The results show that, due to the consideration of wheel–rail adhesion model and traction control in the 3D model, it reports less energy consumption than the 1D model. The maximum difference in energy consumption rate between the 3D model and the 1D model was 12.5%. Due to the consideration of multiple wheel–rail contact points in the 3D model, it reports higher energy consumption than the 2D model. An 8.6% maximum difference in energy consumption rate between the 3D model and the 1D model was reported during curve negotiation.

Deep Sparse Autoencoder for Feature Extraction and Diagnosis of Locomotive Adhesion Status

The model is difficult to establish because the principle of the locomotive adhesion process is complex. This paper presents a data-driven adhesion status fault diagnosis method based on deep learning theory. The adhesion coefficient and creep speed of a locomotive constitute the characteristic vector. The sparse autoencoder unsupervised learning network studies the input vector, and the single-layer network is superimposed to form a deep neural network. Finally, a small amount of labeled data is used to fine-tune training the entire deep neural network, and the locomotive adhesion state fault diagnosis model is established. Experimental results show that the proposed method can achieve a 99.3% locomotive adhesion state diagnosis accuracy and satisfy actual engineering monitoring requirements.

Dependence of Locomotive Adhesion Force Estimation by a Kalman Filter on the Filter Settings

A locomotive needs a slip controller to achieve the maximal tractive effort. Many types of methods are used for this purpose. Some methods use a Kalman filter or other type of estimation. These methods can work precisely and reliably. The Kalman filter provides a filtration of an output signal to eliminate the output signals noise when the Kalman filter inputs are noisy, and a filtration level is required. There is a relation between the Kalman filter filtration level and its delay. The Kalman filter delay can reach over 100 milliseconds. The locomotive slip controller has to react in the order of tens of milliseconds to provide an appropriate function. The high level of filtration and low delay are contradictory demands. The key is to find a relation between the Kalman filter delay and filtration through its covariance matrixes. In the paper is investigated the relation between the filtration level and the time delay. The simulations are made in the Matlab software and based on measured data.

The influence of high temperature due to high adhesion condition on rail damage

In wheel–rail contact, the locomotive adhesion variable characterizes the capability of the locomotive to convert available friction into traction at the interface. Recently developed AC (Alternating Current) drive induces a higher adhesion level compared to DC (Direct Current) drive. This can significantly affect the wheel–rail contact conditions such as high contact temperature due to the frictional rolling, wear and damage initiation of the rails.The aims of this paper are to determine the temperature rise due to high adhesion contact and the thermal influence on the wear and rail life. Three-dimensional (3D) elasto-plastic finite element model was applied to evaluate the growth of temperature, residual stress and strain. The numerical model employed the moving heat source code developed by Goldak within ANSYS/LS-DYNA. The mechanical and thermal properties of the rail material were governed by temperature. The influence of multi-passes from multiple wheels attached to the locomotives on one point of the rail was also taken into account.The results indicated that after six wheel passes, the temperature due to the high adhesion condition was sufficiently high (723°C) to form the white etching layer (WEL) known to be associated to the rolling contact fatigue (RCF) on the rail surface. Moreover the rail material would be softened by high temperature, which resulted in the acceleration of wear process. Finally the results of thermal stress and strain from FE model were used as input to Kapoor׳s ratcheting model to determine the number of wheel rolling cycles leading to rail damage.

Simulation of curving at low speed under high traction for passive steering hauling locomotives

The traction control in modern electric and diesel electric locomotives has allowed rail operators to utilise high traction adhesion levels without undue risk of damage from uncontrolled wheel spin. At the same time, some locomotive manufacturers have developed passive steering locomotive bogies to reduce wheel rail wear and further improve locomotive adhesion performance on curves. High locomotive traction loads in curving are known to cause the loss of steering performance in passive steering bogies. At present there are few publications on the curving performance of locomotive steering with linkage bogies. The most extreme traction curving cases of low speed and high adhesion for hauling locomotives have not been fully investigated, with effects of coupler forces and cant excess being generally ignored. This paper presents a simulation study for three axle bogie locomotives in pusher and pulling train positions on tight curves. The simulation study uses moderate and high traction adhesion levels of 16.6% and 37% for various rail friction conditions. Curving performance is assessed, showing forced steering bogies to have considerable advantages over self steering bogies. Likewise it is shown that self steering bogies are significantly better than yaw relaxation bogies at improving steering under traction. As the required traction adhesion approaches the rail friction coefficient, steering performance of all bogies degrades and yaw of the bogie frame relative to the track increases. Operation with excess cant and tensile coupler forces are both found to be detrimental to the wear performance of all locomotive bogies, increasing the bogie frame yaw angles. Bogie frame pitching is also found to have significant effect on steering, causing increased performance differences between bogie designs.

VLA-4 integrin mediates lymphocyte migration on the inducible endothelial cell ligand VCAM-1 and the extracellular matrix ligand fibronectin.

We herein tested the ability of lymphocytes to utilize the beta 1 integrin VLA-4 to mediate cell migration when adhering to its cytokine-inducible endothelial cell ligand VCAM-1 or its extracellular matrix ligand fibronectin. We used an in vitro system consisting of purified VCAM-1/Fc fusion protein or fibronectin immobilized on porous polycarbonate membranes to quantitatively measure the migration efficiency of an Epstein-Barr virus-transformed B cell line (SLA) and T lymphoblasts derived from normal donors. We found that both SLA cells and T lymphoblasts migrated across membranes coated with VCAM-1/Fc or fibronectin in a site density-dependent manner. Above and below an optimal site density of VCAM-1/Fc or fibronectin, the migration efficiency decreased. A 6-20-fold higher number of lymphocytes migrated across membranes coated with VCAM-1/Fc than with fibronectin. The differential migration efficiency is consistent with a higher number of adherent lymphocytes and a higher avidity of adhesion for VCAM-1/Fc than for fibronectin when the ligands were immobilized on plastic, and is independent of the activation state of the cells. These results demonstrated a stringent regulation of migratory response by cell adhesion strength and a delicate balance between stationary and migratory behaviors of a cell on the adhesive substrates. Like the beta 2 integrin LFA-1, VLA-4 may be a locomotive adhesion receptor which is involved in the transendothelial migration of lymphocytes and the infiltration of lymphocytes into lymphoid or peripheral tissues by binding to VCAM-1 and fibronectin.

The contact between a locomotive driving wheel and the rail

In connection with improving the adhesion of locomotives, a study was made of the conditions of contact existing between locomotive driving wheels and the rail. Observations were made of such measurable quantities as contact area and shape, relative movement or “creep” in rolling, and limiting coefficient of friction, with different values of vertical load, wheel diameter, tractive force, etc. The results obtained were compared with the calculations of Hertz, Carter, and others. Whenever possible measurements were made upon actual wheels and rails, but when this was impossible the problem was simulated by a model in a material giving greater deflection under load. Consideration was also given to the effect of wear upon tyres and rails. In general, reasonable agreement was obtained between actual and calculated values, except that the areas of contact could apparently be increased by roughness of the contacting surfaces, and in the case of creep there appeared to be some additional factor which has so far been neglected in calculation.

Advancing Adhesion—Development and Test of a Chemical Formulation to Condition the Running Surface of Rail for Improved Wheel-to-Rail Adhesion

Abstract Chemical conditioning of rail running surface to overcome the effects of oil films is capable of producing a definite increase in locomotive adhesion. Extensive tests under operating conditions for more than a year have demonstrated its practicability and economy. Characteristics necessary to permit a chemical formulation to qualify for commercial use have been determined and a practical method of application developed. The ultimate objective of application from the locomotive, as is done with sand, is being sought.

The adhesion of electric locomotives

After the results of previous investigations have been considered, the paper describes measurements of adhesion made on electric locomotives on the recently electrified lines between Manchester, Sheffield and Wath. Measurements were made under controlled conditions with the aid of the mobile testing plant on one driving axle of a locomotive, the tractive effort of this axle being separately regulated, and on all driving axles of a locomotive in normal condition, while the adhesion of locomotives working trains in service was observed by the use of dynamometer cars. It is shown that there exists a relationship between adhesion and speed, and between adhesion and water on the head of the rail, while variations in adhesion were found to occur between different parts of the track. A subsidiary investigation revealed that considerable variation occurred in the values of the locomotive axle loads during running. Various methods of temporarily improving adhesion were investigated, such as the use of sand or of certain esters. The conclusions are particularly considered in relation to the working of trains up the Wentworth incline; recommendations are made as to the methods of driving to be employed under difficult conditions; and a modification to the locomotive control to increase adhesive performance is described.