Ellen Bergseth

KTH Royal Institute of Technology | KTH · Department of Machine Design (MMK)

The ability to stop a gear fatigue test before catastrophic failure has many advantages. However, today, a widely accepted approach is not available. This case study applies a vibration-based condition monitoring methodology to detect early gear failures. The gear studied takes part in an all-wheel-drive drivetrain system. Vibration signals from fo...

This paper investigates the resistance of micropitting on two materials, using an FZG back-to-back test rig with C-PT gears. The materials are wrought steel (16MnCr5) and a commercial powder metallurgical material (Astaloy™ Mo). Two finishing methods were studied: grinding and superfinishing. Experimental results show that the superfinishing preven...

Although the efficiency of a gear pair is currently high, a better understanding of surface/lubricant contribution on efficiency is critical. Electrified drivelines will, for example, impose higher speed and alternate loading, and it is expected that these new conditions will, to a greater extent, rely on the surface/lubricant characteristics. Phen...

Thrust washers in spur planetary gears are placed between the planet wheel and planet carrier and act as spacers and wear pads. Metal to metal sliding contact between the planet wheel-washer-carrier causes frictional power losses that, combined with starved lubrication, may cause high contact temperatures and thermo-mechanical effects that potentia...

This paper describes how a wheel-rail wear detection parameter based on noise was developed by running a rapid transit train instrumented with microphones in a depot with a small curve radius. This full-scale test made use of previous knowledge gained from lab-scale tests. The lab and full-scale tests showed that noise could be used as an indicator...

Most freight wagons in the EU use cast iron brake blocks. Cast iron brake blocks have a stable braking capability in different environmental conditions, but wear down the wheel tread quickly. Therefore, there is a need to understand the tribology of other brake block materials. A pin-on-disc tribometer placed in a temperature-controlled chamber is...

A pin-on-disc tribometer placed in a one-way ventilated chamber was used to investigate the effect of relative humidity on the tribology and airborne particle emission of three commercial railway brake block materials (grey cast iron, organic composite, and sintered). Cast iron showed the highest friction coefficient, particle emission and wear los...

Thrust Washers; Planetary Gears; Wear, Surface Treatment

The tribology of an open system at temperatures ranging between 3 °C and −35 °C, with and without snow, was investigated using a pin-on-disc tribometer mounted in a temperature-controlled environmental chamber. The relationship between the microstructure and ductility of the materials and the tribology at the contacting surfaces was investigated. T...

The wheel-rail system operates in an open environment where the weather condition varies constantly. In this laboratory study, an investigation using a pin-on-disc tribometer placed in a temperature-controlled room was conducted to examine the effect of subzero temperature and snow on friction and wear at the wheel-rail contact. In temperature rang...

An on-board measurement system has been developed that in real time identifies the probability for occurrence and also the exact location of severe wear in the wheel-rail contact. Noise generated by the wheel-rail contact is a troublesome side effect both when railway vehicles negotiate curves and run on straight tracks. The concept behind this pro...

Coating is one of the innovative approaches used to improve the wear resistance and load-carrying capacity of surfaces in rolling-sliding contact, such as gears and rolling element bearings. In this study, the tribological performance of standard gear material (EN 16MnCr5) and two kinds of powder metallurgy (PM) gear material (Distaloy AQ + 0.2% C...

Noise from the wheel-rail interface is a troublesome side effect when railway vehicles negotiate rail curves. In this laboratory study, two pin-on-disc tribometers were used to simulate the pure sliding process in the wheel-rail contact. The purpose was to investigate the relationships between surface topographies, tribological aspects and the emit...

In this study, a twin-disc test machine was used to simulate a rolling/sliding gear contact for three surface finishes, each run with two types of lubricants, thus seeking to develop insight into the tooth flank/lubricant tribological system. The test disc surfaces were case-carburised before the surfaces were produced by: transverse grinding follo...

Gear tooth modifications, such as lead crowning, are often recommended to compensate for misalignment (e.g. assembly deviations). Lead crowning means that the tooth centre is slightly thicker than the tooth edges and is usually described as a circular arc profile. The use of crowning shifts the peak load from the tooth flank edges and therefore red...

The purpose of the study was to examine the tribofilm formation and the corresponding wear occurring in the boundary lubrication regime in environmentally adapted lubricants, i.e. when using synthetic ester base fluids with different anti-wear additives. AW additives of the following types were studied: phosphorus, sulphur–phosphorus and sulphur–ni...

Hobbing is a widely used machining process to generate high precision external spur and helical gears. The life of the hob is determined by wear and other surface damage. In this report, a CAD approach is used to simulate the machining process of a gear tooth slot. Incremental removal of material is achieved by identifying contact lines. The paper...