Engine lift/setback brackets

[jw.]

I bit of info required please. When winding an engine up using the screw on a mechanical engine lift, does it come up easily?

[Jono]

Yup.... but then I'm *cough* 19 stone*cough* of Brummie knuckle-head.... so perhaps you shouldn't listen to me...

[Matt]

On my old one, yes, but ya had to slacken (slightly) the 4 big bolts at the sides first. And I only weighed 11 stone then

[jw.]

Ok guys, thanks. I'm gonna make a lift with 350mm of travel and 200mm setback and I've got a nice piece of M20 studding and some big, fat, nuts. So, next question; did the screw run in a stainless nut or did it use a bronze nut?

[Jono]

Originally posted by jw.
Ok guys, thanks. I'm gonna make a lift with 350mm of travel and 200mm setback and I've got a nice piece of M20 studding and some big, fat, nuts. So, next question; did the screw run in a stainless nut or did it use a bronze nut?

C'mon JW ? A man of your knowledge? Stainless steel threads like-for-like under load? Galling?....

Now I've opened my big mouth, I suppose you're gonna tell me the studding isn't stainless.....

...I'll just close the door on the way out shall I ?

[jw.]

Originally posted by Jono
Stainless steel threads like-for-like under load? Galling?....

Yeh, I ken, thats why I asked. I just wondered if well greased and under water there would be enough cooling to prevent them picking up. (And save me a bit of work.)

So I guess that's a, "Yes JW, they used a bronze nut."

Ta Jono.

I'd better go hone up me thread cutting tool...

[Jon Fuller]

Actually, I think the CMC one was just galvo stud/nutz

[Jono]

Originally posted by jw.
cooling to prevent them picking up. ....

Just being pedantic here... God, I love that word.... and seeing as I'm just about to argue the same point with a so-called engineer who wants to suspend a load of my Cyclones from a 304H threaded rod and nut...

[Rant mode]How come kids can come away from university knowing less than a lad who works on the shop floor? [/Rant mode]...

Galling is other wise called cold welding or cold seizure. Temp has nothing to do with it. The heat you feel when a thread is galling is the heat generated when you "tear" the weld apart...

If you want to use S/Steel use different grades for the nut and Stud. Then a good coat of something like Molykote (Molybdenumsulphide based) should do the trick......

[jw.]

Originally posted by Jono


Galling is other wise called cold welding or cold seizure. Temp has nothing to do with it. ..

Does it not. I always imagined it was kinda micro spot welding because of friction on tiny irregularities on the surface.

Jono, give us an explanation of what's goin' on. Seriously.

[Jono]

JW, Excuse the use of "layman" language, unfortunately I didn't go to university to learn the "proper" terminology. My understanding has come from painful experience. Years ago I had to release a set of galled hanger rods about 100 foot up... and those puppies were 120mm diameter... never let a monkey assemble precision components.. when they started to pick up on assembly... they put a scaffold tube on the spanner..... nice! ...and still we have designers/engineers dreaming up the same old problems...


Think of it not a "spot welding" but as micro friction welding. Once its starts it tends to "roughen" the mating surfaces as each "micro weld" is torn apart and spalls material. So technically yes heat is involved, but not because the components get hot…… if that makes any sense? The worst cases are when you use matching parts with the same cast analysis. They are so alike chemically that they want to form a bond, so when they are put under load in a mating condition that's what they try to do

[jw.]

Thanks for that, Jono.

That's about what I imagined. And bad on stainless because of it's poor heat conductivity. The heat thing I didn't make myself clear, I reckoned the water would be inside the nut and applying a degree of cooling at the rubbing surface along with the grease.

Unfortunately, I've no idea which grades of stainless the studding and the nuts are. Do you know whether they spark differently on a grinder?

[Jono]

Any markings on them at all? Usually stamped on the end of the "stud" look for B8Msomething for 316 and Nuts Gr 8Msomething 304 B8 and Gr 8 without the "M"....

Sparking will produce very minor colour differences indeed... too small for the naked eye to tell, but the basis for instrumentation used for Material Identification such as the Metascope....

Yeah, yeah.. I've got a anorack....

[Dan]

Any form of marine application you should always use 316 or 316L (L stands for lower carbon). 304 is a fair bit cheaper as it has a higher carbon steel content.

[Jono]

Originally posted by Dan
Any form of marine application you should always use 316 or 316L (L stands for lower carbon). 304 is a fair bit cheaper as it has a higher carbon steel content.

Say what????.....

[jw.]

Originally posted by Jono
Any markings on them at all? Usually stamped on the end of the "stud" ...

Should have looked again before I posted. Nuts are A2-70 and studding has red ends. Is there a colouring standard?

[Dan]

Originally posted by Jono
Say what????.....

Basically anything marked as 304 (ie the material) should not be used on near or in water, thats all, as it WILL rust.

Should have looked again before I posted. Nuts are A2-70 and studding has red ends. Is there a colouring standard?

The A2, is the grade of stainless. For marine application you should really be looking for A4. As for the colour coding, I think most of the steel supplier have there own. If in doubt give Aalco a call, they are in Southampton on 02380 875200

[Jono]

Nuts are 304 then... there is a colour coding standard.. buggered if I can remember what it is though.. I'll do a bit o'digging and see what I can turn up...

...found it. If it's a S/steel to a BS spec it is NOT 316. The colour for that is green. If it's red it's likely to be 303s31... but be careful it's not a mark put on by any old nob jockey....

[Jon Fuller]

Originally posted by Dan
Basically anything marked as 304 (ie the material) should not be used on near or in water, thats all, as it WILL rust.

not always.

if the surface is polished, it appears to be ok, in this pic, all the steering system, rams, brackets, tie bar etc, and the C/S bollts holding the lifting eyes on, are 304, and 4 years old.(actual lifting eyes are 316)

[Jono]

Originally posted by Jonny
not always.

if the surface is polished, it appears to be ok, in this pic, all the steering system, rams, brackets, tie bar etc, and the C/S bollts holding the lifting eyes on, are 304, and 4 years old.(actual lifting eyes are 316)

I was going to put it slightly differently.....

[Johnny Rocket]

Originally posted by Jono
I was going to put it slightly differently.....

Must be my diplomatic skills rubbing off on him