Member postings for Russell Eberhardt

... and mine. This is where I learned about electrical machines. HSE would have a field day!

Russell.

Edited By Russell Eberhardt on 13/03/2013 16:06:10

...and quite often when they have!

Russell.

There's a comrehensive explanation of electronic PFC here for anyone interested.

Russell.

Ah! A real engineer. Everyone else calls it "i".

Russell

Hi Swarf, Mostly,

A modern, less bulky and costly, alternative to using a large choke (inductor) is active power factor conversion which uses something akin to a switched mode psu to make the current drawn more sinusoidal.

Russell.

Posted by David Littlewood on 09/03/2013 23:07:52orry to disagree with you, but the out-of-phase current flows in both directions, so it does go backwards and forwards along the transmission cables, causing losses.

Yes, of course it does - doh! In exactly the same way that in phase current does - it's AC!

Russell.

The out of phase current doesn't go back again but, yes, you're right. That current flowing through the cable resistance will develop a voltage drop in phase with that current and therefore will absorb power.

Russell.

Yes it is the terminology. Power is the rate of flow of energy.

In an ac system power is given by P = I x V x cos( θ) wher I and V are the rms current and voltage respectively and θ is the phase difference between the voltage and the current. Thus, if θ is 90 degrees as it is with a reactive load then there is no net power flow. There is, of course a flow of current into a reactive load but it doesn't transmit power. If you like it "borrows" it. What they are talking about in that link is what we used to call VA or volt-amps.

If you are sure that you can work safely you could connect a large capacitor such as a motor capacitor across the mains output of a plug-in mains power and energy monitor. Tou will see that you can measure a significant current but the power will be zero.

Russell.

Bit of swarf/dirt/paint in the V groove under the tailstock base?

Russell

Official spec. for single phase in UK is now 230 -6% +10% so 216V to 253V, The UK suppliers like to keep it at the high end as it increses consumpltion and thus revenue! If they keep it normally at 230V instead of 240 their revenue would go down by about 8%

Russell.

Reactive power? - no such thing. Reactive current, ie., that drawn by an ideal capacitor or inductor is 90 deg. out of phase with the voltage so there is no power. Power is he vector product of current and voltage.

So to answer your question, Michael, as to what happens to this reactive power, the answer is nothing as it doesn't exist!

Russell.

All this talk about HT bolts is irrelevant. The OP is asking what steel to use to make shackle pins. These are pins that run in a bronze bush, completely different to the fixing on modern vehicles.

Wheatly & Morgan, the bible for vintage car restorers, recommends making them from Kayser Ellison's KE805 steel. This has a composition of; C 0.38 Cr 1.0 Mo 0.2 Ni1.5 balance Fe. However I have successfully used EN8.

Russell.

As the spring has a bronze bush you need to inspect it to see if it is worn and needs replacing. An HT bolt as bought will not be suitable as it will be undersize and won't have provision for greasing. You will need to buy or make something like these:

You will note that they are drilled for grease from a nipple that screws into the head. They have a ground finish although a good turned finish, polished afterwards will do. They also have some provision to stop them rotating. This is very important otherwise the shackle plates will wear.

They should be made from a reasonably tough steel such as EN8 (you could,at a push turn them from larger HT bolts)

You might be able to source some suitable steel locally from a machine shop. Look in the Pages Jaunes under "Rectification, usinage, fraisage".

Bon chance,

Russell.

Edited By Russell Eberhardt on 07/03/2013 07:35:51

I don(t know about Citroens but I have restored a number of 1920s and 1930s cars. Late thirties cars usually use a "Silentbloc" bush and an ordinary HT bolt. Earlier models usually have a bronze bush fitted to the spring and a pin that is case hardened and ground, usually with drilling for grease nipples. It is possible to do the case hardening at home but there may be problems with distortion. The best way is to use a special nitriding steel and get the surface nitrided professionally.

Having said that, I have made pins from EN8 steel and used them for years without problems.

Russell

In this part of the world it's called "Petrole" don't confuse it with petrol!

Russell.

Rocol RTD compound. (RTD = reaming, tapping, drilling) It's a sticky paste so retains the swarf. Great for tapping and threading but not suitable for milling and turning. Use Pter's recommendations for that or soluble oil for steel.

Russell

Sorry, finger trouble again. I meant 500 rpm of course.

Russell.

The pulley diameters you quote will give about 1500 rpm. OK for turning 18 mm but I would want to reduce the speed to about 1/4 of that for parting, especially on a small lathe. Yes a thinner blade should help - half the width = half the cutting force.

Russell.

This must surely be a myth. Diamond is pure carbon so if any "leaching" is to take place it would be in the opposite direction. Diffusion concentration gradient and all that.

Russell.

Or get it centreless ground to remove any scores or taper and then make new, unndersize, bronze bearing bushes.

Russell