Tps

[Trevor]

Quote : -

Ò You've thrown down the gauntlet, so I'll pick it up! I'll measure the voltage & current through the range of motion with varying pressures
on the contacts. I should be able to do this with the signal generator and the scope. (and several pieces of #6 lead shot) Ò

You will be involved with measuring micro ohms and will not be able to measure the sort of variation you can create by ordinary means. If you can prove that the resistance between two electrically conductive bodies does not vary with pressure between them you will go down in history. Consider these facts. Taken in absolute terms the two conductive bodies are rough and malleable and increased pressure will result in an increased area of contact.

However I am sure we are at cross purposes and no gauntlet should been thrown as you are somehow missing the point I am making.

If the contact blade becomes fatigued through time there will come a point where contact will become intermittent and this is why I stress contact pressure is important i.e. no pressure at some point and no contact. Any dust or deposit on the element also comes into the picture as a low contact pressure will not be able to break through the contaminate.

Maximum pressure in the original designed/manufactured state therefore has an advantage as there is built in tolerance and this is a vital issue when designing a moving contact assembly.

The major factor effecting fatigue in the blade contact arrangement we are considering here is the length of the spring blade. A superior design, which is often seen, would have a much longer radially shaped blade providing greater over travel.

When I referred to contact resistance in connection with intermittent contact I was meaning very high resistance and near to an open contact. The point made is that low pressure can result in intermittent contact at some point in a moving contact assembly. If pressure has deteriorated and can be restored the result is a fix.

In actual fact I think we are on the same track even if it is a resistant one.

<<In actual fact I think we are on the same track even if it is a resistant one. >>

We actually are! even ignoring the pun, as shocking as it was...

I will now free up Saturday afternoon for more leisurly pursuits...

Oh yeah, Saturday is rear wheel bearing day...

Wish me luck

Cheers, Collins