BSA Gear material???

[chaterlea25]

Hi All,
Here I go off on another BSA tangent  
What reminded me was when I saw this ebay add no. 300607825180 (BSA gears)
The vendor states that the gears are stamped V18    ????
Now to the best of my research a long time ago, with Rudge gearboxes, it should read VIB whicjh is short for Vibrac
Apparently Rudge racing gears were of this material??? and they shouldnt be mixed with unmarked gears

When I bullt the gearbox for my SR I tracked down with great difficulty a set of new gears (1 at a time )
which are marked EN36
I'm sure the metallurgists out there will know what this stands for  ????
I had found some gears with V18 or VIB and some gears without markings???

I never bothered to compare different part numbers from different BSA models that share the same style gearbox to see if the part numbers are different  
One thing I do know however is that the heavyweight C11 gearbox gears only have half the number of engagement dogs on them   (on the fine pitch dogs)

I have heard of people fitting these to A10's

I have built a fair few A & B gearboxes since then, but since I was reusing the original gears or a donor cluster I havn't studied the markings on them

Cheers
John O R

[MG]

Hi John!
EN36 is case hardening steel with 3.5% Nickel and 0.9% Chrome. It can be carburised and thus hardened up to some 60 or so HRC. Makes sense for gears.
Got no clue what Vibrac is though (was a bit before my time  )  ????

Cheers, Markus

[chaterlea25]

Hi Markus,
I knew you would jump in and give the technical details 
I knew its the dogs for gears (LOL!!)
I had a pair made for the Moss gearbox for my Chater lea from EN36 
Cheers
John O R

[MG]

Ha, look what I found:

http://query.nytimes.com/mem/archive-free/pdf?res=F70C14FD355810738DDDA00994DB405B828EF1D3

This being an article from 1922, reporting the discovery of Vibrac Steel. According to cross reference lists, Vibrac 30 and Vibrac 45 are equivalents to EN25 and EN26, common general engineering alloy steels with 6% Cr and Mo, 2.6% Ni and 0.3 to 0.4% Carbon, which make them suitable for direct hardening (quenching and tempering).

Now all we need is an expert on tribology to tell us why they shouldn't be mixed.  
I can't see any obvious reason, provided the surface hardness level is roughly the same on matched gear pairs.  ????

Who let the dogs out ????  

Cheers, M

[chaterlea25]

Hi Markus,
If I remember correctly the reccomendation was not to mix Vibrac and "non" Vibrac gears on the same pair of gears
I think the "sports/ racers had the VIB gears, it didnt apply to mere "Special" models??
On Rudge gearboxes one gear is integral on each shaft, and a big load of loose rollers 

Thanks for the link
Cheers
John O R

[Topdad]

Hi Markus and john, re the Vibrac and the components of various steel . My brother is a retired metalurgist and talking to him today he had to think hard about Vibrac ,his conclusion was a 1920's specialist firm steel made in small quanaties ,which would fit with the rudge connection and then went on to talk about various en 35 etc starting from about EN16 and others around that spec /age and he mentioned something I found interesting . I wasn't aware what if anything the en meant and he told me that it was actually an obsolete classification which had continued in use by the engineers who still ordered using that name. This confirms why ,the EN was introduced circa the first world war "EN= Emergency spec " to allow for standardisation by the various companies making steel for the war effort and had continued ever since and that poeple confused the old en numbers with the more modern en which stand for Euro Norn.He  also said that should anybody need any info re old spec's and uses he could oblige,anyway hope you find some of this of interest regards BobH.

[alanp]

While I was involved in machinery design the steel specs changed from En numbers and have to say the new (not so new now!) numbering system is clever but much more difficult to remember and talk about. E.g. En 19 is now 709M40 and  En 36 is 655M13, I think, see what I mean?  

[wilko]

I can't see why you can't mix steel gears consididering they have oil or grease as the lubricating medium to theoretically cushion between the two.

[MG]

his conclusion was a 1920's specialist firm steel made in small quanaties

Armstrong, Whitworth and Co. of Manchester, according to the article 

[BSA_54A10]

I can't see why you can't mix steel gears consididering they have oil or grease as the lubricating medium to theoretically cushion between the two.

There is absolutely no reason not to use the different gears together if all that was different was the material.
However more likely was that they were cut differently so would not mesh properly.

Metallurgy did not really advance greatly till the advent of spectrochemistry. ( I include chromotography with that )
This allowed real time control over the chemistry of the metal.
Prior to that different foundries used different combinations of scrap metals to control the product ( sort of works ) .
Each foundry would have their own "secret" formula which they generally gave a catchy name to like "Meanhite "  "Vibrac" , "Wearpac" or "Muntz".
These would all be touted as having special "exclusive" properties, a practice that still is used today.
How many of you have used "colobro" valve guides in alloy heads ?