In my previous articles on the difference between leaded and lead-free bearing shells materials, the heat transport from oil through the bearing shell to the crankcase was discussed. In this article the current status of the leaded bearing is described.
First though I would like to pass on a remark made to me when talking to a well-known bearing shell supplier. When discussing the possible reasons why leaded bearing materials are still favoured over lead-free materials, Read more…
In previous articles about the differences between leaded and lead-free bearing shell materials, several reservations about the latter have been discussed, one of which is the heat transport from oil through the bearing shell to the crankcase, where leaded bearings are said to have the advantage. In this article, I want to offer further insight into the temperature differences between the two materials.
The data here is to be read as relative between the two materials: due to the differences between the several Read more…
In the July 2010 issue of RET-Monitor, keyword: bearings, I wrote about lead-free bearings and possible engineering concerns surrounding their introduction. Extending the search for the reasons behind why the substitute for leaded bearing materials is not yet embraced by the race engineers led to a short interview with a leading supplier of competition bearing shells.
In addition to possible sensitivity issues concerning roundness (shape and steps in the circumference of the bearing bore) and the lower conformability and embedability of the unleaded, harder materials, the temperature inside the bearing is considered to be of major importance in the selection of the bearing material.
In another article in this issue of RET-Monitor, I have given what I hope is an insight into crankcase main bearing split design (keyword: heads-blocks). Background is the accuracy of the main bearing split line geometry, primarily focused on the roundness of a main bearing bore.
Since the crankshaft system does not directly rotate in the bearing bore, we will look at the bearing shells in between. As John Coxon wrote in the May 2010 issue of Race Engine Technology
In most motorsport applications, bearings have had to cope with increasing loads as the requirements for higher performance of engine, gearbox and suspension components continues to increase.
Recalling his days at Tyrrell, Renault’s Formula One chief designer Tim Densham says, “Normally you would just open the SKF book and pick out standard bearings for most of the shafts.” Things have moved on somewhat from those days, although even then some companies did make Read more…
Once problems with rolling element bearing reliability have been chased in NASCAR Sprint Cup Series competition, is it worth trying to gain performance improvements?
The rolling element bearing does consume some power. While mechanical losses are worth a little more than you might think, there are actually two gains made for every reduction of mechanical loss implemented. Read more…
The terms rolling contact bearing, anti friction bearing and rolling element bearing are used to describe that class of bearing in which the main load is transferred through elements in rolling contact with each other. Friction in a rolling element bearing is present, but it is negligible when compared to the starting friction of a journal type bearing. The load, bearing speed and the viscosity of the lubrication all affect the friction within the bearing. Although it is not technically correct to refer to this type of bearing as anti friction, it is a name that is in constant use. Read more…
Traditional main bearing construction is based on a three-layer bearing made of a steel backing, a hard mid layer and a thin overlay of a soft material.
The bi-metal bearing is constructed of only two layers, consisting of a steel backing with an inlay of an aluminium alloy. Typical bearing materials used in the construction of bi-metal bearings are a combination of the following materials: Tin, silicon, lead, copper and aluminium. The bearing Read more…
Traditional journal bearings for internal combustion are of the tri-metal type. This type of bearing consists of a steel backing, a hard middle layer and a soft top layer. Typical soft bearing materials are: lead, tin, zinc, or alloys of these metals while typical hard bearing materials are: Aluminium-tin; lead-bronze; copper-lead. The soft top could comprise of three layers, providing five metal layers.
Journal bearings operate between the extremes of no lubrication on the one hand, to thick-film lubrication on the other. Therefore, bearing material must possess Read more…
FATIGUE AND WEAR IN A JOURNAL BEARING (during start-up and boundary lubrication)
When two bodies are pressed together contact stresses occur. The results of the work done in this area are due to Hertz and are referred to as Hertzian stresses. Two special cases of hertzian stresses are: contacting spheres and contacting cylinders. An example of contacting spheres would be a single row ball bearing, with a single ball contacting the inner surface of the inner or outer race. An example of contacting cylinders would be a Read more…
