| 1. |
- Nilsson, Rickard, et al.
(författare)
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Filtration and coating effects on self-generated particle wear in boundary lubricated roller bearings
- 2005
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 38:2, s. 145-150
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Tidskriftsartikel (refereegranskat)abstract
- A specially designed test system involving boundary lubricated roller bearings was used to study wear at low particle concentration levels. A separate oil system circulated the oil through the test bearings. The effects of self-generated contaminants from the system were studied. Even at very low concentration levels, self-generated contaminants can cause significant wear. The concentration of self-generated particles was very high during the running-in period. It is therefore important that the filtration be very efficient during this period. The experimental results show that filtration during run-in for 1 h with a 3 μm filter can reduce both the mass loss and the number of self-generated particles by a factor of 10. Furthermore, the results also show that while the bearings with standard rollers can have significant wear, those with coated rollers are at the same time almost unaffected by wear. Also, the number of particles generated in the contact was significantly less when using coated rollers. There were twice as many self-generated particles when using a standard bearing as those compared with a coated bearing.
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| 2. |
- Olofsson, Ulf, et al.
(författare)
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Influence of leaf, humidity and applied lubrication on friction in the wheel-rail contact : pin-on-disc experiments
- 2004
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : SAGE Publications. - 0954-4097 .- 2041-3017. ; 218:3, s. 235-242
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Tidskriftsartikel (refereegranskat)abstract
- A novel test method has been used to study how applied and natural lubrication (leaf and humidity) influences the coefficient of friction in the wheel-rail contact. A pin-on-disc tribometer placed in a climate chamber was used as the test equipment. The pin-on-disc contact simulates the wheel-rail contact caused by commuter train traffic on straight track. The results show that the coefficient of friction decreases when the relative humidity increases and decreases even more when a leaf is used as a lubricant. By using an elm leaf as the lubricant, the coefficient of friction is reduced by a factor of four compared with the unlubricated case. However, the coefficient of friction decreases even more when a rail lubricant is used.
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| 3. |
- Sundh, Jon, et al.
(författare)
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Seizure and wear rate testing of wheel–rail contacts under lubricated conditions using pin-on-disc methodology
- 2008
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; , s. 1425-1430
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Tidskriftsartikel (refereegranskat)abstract
- An increased wear rate and a shift of wear mechanism in the wheel-rail contact has been observed in tight curves, mainly due to the change from an almost pure rolling contact to more of a sliding contact. The wheel flange-rail gauge contact is commonly known to experience the toughest conditions of the overall wheel-rail contact in terms of contact pressure and sliding velocity. The wheel flange-rail gauge contact is preferably lubricated to reduce the wear rate and to minimise the risk of transition to severe wear or seizure. The amount and type of lubrication are therefore important parameters if one is to control the wear rate. In this study, a flange contact is experimentally simulated using pin-on-disc testing, to determine the difference in wear rate among a selection of lubricants under different contact conditions. The selection of lubricants consisted of environmentally adapted oils, mineral oils, and greases containing different amounts of EP and AW additives.The results of the pin-on-disc testing indicate that both the amount and type of lubrication applied is decisive for the wear rate and active wear mechanism. Tests have also been performed to simulate either on-board or wayside lubrication, by applying the lubricant at different intervals. A general observation is that under starved lubrication conditions a transition to severe wear is initiated and the wear rate increases rapidly, i.e., all tests indicate that the contact between wheel and rail must be lubricated to avoid high wear rates.
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