Many years ago, as a young and somewhat naive apprentice, I was told by my training supervisor to go to the engineering stores and ask for ‘a long wait.’ Thinking that this was some form of specialised turning tool, I dutifully did as requested only to be told after 10 minutes at the counter “You’ve had your long wait, now clear off!” Engineers and former apprentices of a certain age might recognise my continuing embarrassment. So when the idea of the...
Historically, the relatively soft grey cast iron cylinder liner with its inclusions of graphite, correctly prepared, has made an excellent material when running against much harder chromium plated rings. However, the differences in thermal expansion between the liner and that of the aluminium alloy piston make it necessary to introduce a greater than desirable radial clearance to prevent piston scuffing and eventual seizure. As the specific performance increases along with larger diameter...
In the first RET Monitor Seals and Gaskets article, we started to examine the research which Trelleborg Sealing Solutions, a leading multi-national manufacturer of gaskets and seals, has published into the interaction of sealing compounds with biofuels. This research will cause fuel system designers to rethink material selection for sealing gaskets and O-rings. In that article we focused on water contamination of bio-diesel, something which is to an extent, almost inevitable. Water...
In one of the previous articles, the discussion points were on the traditional methods of manufacture, and this month we shall look in more depth at non-circular sections in exhausts. In the article dated June 14, we mentioned pressed mends as a means of being able to produce very tight radii where space constraints require this. Of course, there are other applications of pressed parts in exhausts, especially where the space envelope is tight. As we know, the aero departments have a great...
Last month, we looked at some basic calculations regarding cyclic loading of fasteners. Engine design engineers need a good understanding of the subject in order to correctly design the optimised fasteners required, but also those whose business is in improving the performance of engines need to be able to calculate when the standard equipment just isn’t going to be good enough. We examined the concept of load coefficients and looked at a very simple example of how the load...