My rod ends were hardened steel with brass sleeves - they also had oilers. They were just the cheeper ones, not SKF or anything fancy. Not sure why yours are wearing out. Mine had about 4:1 ratio and I weigh 110kg, so they were quite well loaded. Although about 60% of my weight was probably on the front wheel - leaving 44kg on the back, say 22kg each side - so about 88kg static and maybe 250kg dynamic. I believe they could handle about a ton.
15 x 1 square tube is a bit light. I did static FEA on my rear swing arms and 35 x 1.5 RS was needed to take my weight, but mine used single canterlevered sections of C450 (which is a high carbon structural steel), rather than the triangulated approach you have used.
-h Henry Thomas On 20/09/2011, at 5:56 AM, Patrick van Gompel wrote:
Henry, I checked your dimensions for the swing arm again. Mine are a bit larger, but I have about the same relation: 1:3 for the arms (about 30cm for pivot point to axle and 10cm for pivot point to the link connection point). So 10kg load on the wheel will be 30 kg load on the link going to the rockerarm. Not sure why I have problems with this connection and you don't. My M6 economy rod ends where worn out very quickly (without using the trailer). My double M8 rod ends on the rocker arm have signs of wear too and the 15x15x1mm square tube is deformed by the pulling load. I did buy new M8 PTFE rod ends for the links and M10 for the rocker arm, but I haven't installed them because I was testing the strings. But I am in doubt now whether they are strong enough. This M8 PTFE rod end has a 5.85kN dynamic load rating which is only about double the amount of my worn out M6 rod ends.
