Leaf springs - to coat or not coat

Hi all,

I would be interested in peoples' experiences/recommendations regarding coating of leaf springs (or not).

I guess for the majority of locos with underslung springs, they tend to get covered in oil & crap pretty quickly and are i) not prone to corrosion, and ii) generally not visible. However, for tender springs, which tend to be mounted externally above the axlebox, and are quite prominent and not prone to coating with gunk and other crap, there is a question of whether to paint the outside of the leaves to keep them protected from corrosion and make them look nice.

There are various graphite-based coatings used in the classic car world, but these seem to be hard to get hold of, and perhaps not cost effective for coating a large number of big springs. The other alternative is graphite-loaded grease, but this may leave a 'sticky' surface which isn't perhaps what's needed either.

If anybody has experiences good or bad, or recommendations for products, it would be good to hear from you. Thanks in advance.

Cheers
James
44123

 

Once told to leave the springs alone when cleaning/greasing round, friction between the leaves provides a damping action - grease them and they loose this and become... well erm 'springy'.

 

I just wire brush springs on coaches and wagons then give the outsides a coating of lubricating oil.

Bob.

 

You're correct that leaf springs have a high hysteresis due to the friction between the leaves. However, if it was that critical it would soon become a problem on underslung loco springs. I'd simply clean them with the usual cleaning mix of lub oil and paraffin and wipe it off. Better than getting fretting and the tell-tale brown deposit.

 

When I was with BR we were told never to lubricate springs as the friction between plates was important, the resulting friction provided damping.

 

Thanks for all the replies folks.

Does anybody have experience of painting springs with conventional paint? I know spring manufacturers/refurbishers do coat springs with some kind of paint system (not sure what), but it doesn't appear to be very thick or provide much resistance to surface rusting.

Something about painting spring with oil-based paints as used on chassis etc feels wrong to me, albeit I can explain quite why.

 

Since it is -possible to design a spring which does exactly what is required when lubricated, and utterly impossible to predict how it will perform when unlubricated, rusty, and full of crud, I am extremely sceptical that any loco designer required or intended springs to be left unlubricated. It is possible that it became official policy but suspect that this wasn't for engineering reasons.

I have always greased the leaves of leaf springs before assembling them, whether for road or rail use, and have always been led to believe that this was best practice.

Whilst not immediately relevant to rail applications, it is perhaps of note that many (if not most) quality pre-war road vehicles had lubrication systems which oiled their leaf springs, and such springs were usually gaitered to keep dirt out and lubricant in. A completely different scenario to a locomotive or similar I accept, but this tends to support my contention that the only predictable leaf spring is a lubricated leaf spring.

 

In my experience springs above the running plate are usually painted. I’ve not had any problems in so doing.

 

In my day job we regularly paint (and line) the front axle spring of traction engines, a prominent feature. We always use Craftmaster paint and have never had issues with the paint cracking off due to flexing. One tip, when painting springs, cut dry paint along the leaves with a blade after every coat, it stops paint tearing and wrinkling the first time the spring flexes

 

Although older cars with cart springs often had gaitors and lubrication, they also had some form of external damping or shock absorbing. Railway leaf springs on locomotives and rolling stock do not have these and so not lubricating between springs does aid the friction/damping as gwalkeriow has mentioned. We usually paint our windcutter wagon springs with black underseal or gloss paint. Then we may brush on some old oil.