In recent years the push towards more fuel-efficient, direct injected engines has led to increased peak cylinder pressures and higher bearing loads. In order to support this higher level of performance, therefore, plain metal shell bearings have had to offer better fatigue resistance alongside improved conformability. Although aluminium-tin-silicon (Al-Sn-Si) bearings have been around for many years, and give good conformability in applications requiring lesser performance, in the search...
Friction in an engine means different things to different people. To some it equates to lost power; to others it is lost fuel economy, while to the environmentally aware it represents increased engine emissions, and so faced with these it is little wonder that great emphasis is placed on reducing it. Low-tension oil control rings, minimal sized bearings – both big end and mains – or variable flow oil pumps to match precisely the oil required by the bearings and no more, these are...
Much of the focus in recent years in terms of coatings used in motorsport powertrains has been on the hard low-friction coatings, such as titanium nitride, chromium nitride and diamond-like carbon. These have served to reduce friction and increase the allowable contact fatigue stress in some critical components. Metallic coatings of any description have struggled to be newsworthy though, as they are unable to come close to the new engineering coatings in terms of hardness, friction or wear...
In the previous article, there was a picture of a very basic Scotch Yoke mechanism, and the mechanically astute among you would have noticed some obvious problems with such a basic implementation of the principle behind it. The two glaring ones are high contact pressure in the contact between the crankpin and the slot in the con rod, and the lack of stiffness in the rod. If we deal with the first of these, this is solved relatively easily. If we interpose a bearing block between the...
Over the years, many automotive parts have been made from rubber. Initially made from the latex of the rubber tree, the security of supply and the vast amounts needed during the 1920s and ’30s encouraged the development of synthetic alternatives. So while cooling system hoses may once have been made from any number of synthetic rubbers, these days they are restricted to more or less only two – ethylene propylene diene monomer (EPDM) and silicone. EPDM is the product preferred for...