Field and laboratory assessments of the friction coefficient at a railhead

Abstract

The aim of this work was to prove that the oil applied to the wheel flange using on-board lubricators not only alters the friction coefficient between wheel and rail but also influences the braking and acceleration performance of trains on one of the lines of the metro in Mexico City. A series of tests were carried out in the presence of an oil lubricant, both in the laboratory and in the field, using a pendulum tester. It was observed that the oil migrated from the rail corner to the top of the rail. In another set of experiments, water was sprayed onto the lubricant on the top of the rail. The results indicated that under these conditions, the friction coefficient has a low value in rail sections where a high value of the friction coefficient is required. Tests with water/oil mixtures presented similar levels of friction to the oil-only tests. A set of tests were performed after the rail surface was cleaned and the oil lubricant and water were applied together. The laboratory and field tests showed similar behaviour trends for the friction coefficient. The pendulum method can be used to assess railhead friction on short-length sections of rail. Points are made regarding the conditioning of the pads and calibration of the pendulum arm.

Optimal operation of a rail lubrication device with respect to noise reduction and wheel/rail friction coefficient

“…When a high viscosity material is used, the value of the friction coefficient can fall below 0.1, for example in case of oils, but it can also drop drastically in case of freezing. There is also an example of the effect of the use of oils [9], where the slip of the wheels of vehicles is certain, since the value of the coefficient of friction was measurable well below 0.1. There are several studies on how traffic is affected and disrupted by water or falling leaves in autumn [10].…”

Sand as a friction coefficient improver on asphalt ice layers

“…For example, friction occurred on the top of the rail in the laboratory and the field under different surface conditions, surface textures and friction enhancers for railway systems, dry leaves, oil, and dust, among others. 13,14 On the other hand, the pendulum can be used to determine the slip resistance value of floorings of public buildings and several materials and textures of sidewalks, 15,16 including the evaluation of some flooring materials such as marbles, limestone, travertine and granite in dry and wet conditions. 2 Further, some researchers have studied the behaviour of the friction coefficient in icy conditions on metallic surfaces, road surfaces, and elastomers.…”

Dynamic Behavior of Worn Wheels in a Track Containing Several Sharp Curves Based on Field Data Measurements and Simulation

“…The wheel/rail wear has also been extensively studied previously, and the important experimental research pieces were reviewed by Lewis and Olofsson [8], Sheinman [9], and Wang et al [10], etc. Some of the experimental studies were either conducted through laboratory tests [11][12][13][14][15], simulations [16][17][18][19][20], or experience and measurements on in-service vehicles on tracks ( eld experiments) [13,19,21,22]. The di culties and expenses involved in the eld experiments have forced researchers to use the laboratory tests and simulations, whenever possible [6].…”