Thoughts from Meltham

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Nowtnew
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Thoughts from Meltham

Post by Nowtnew »

In order to help out a friend, I recently had to acquaint myself with a David Brown 990. In the course of this two points of interest arose:

Looking at the service schedule I found that the recommended lubricant for the king pins was ep140 oil rather than grease. I'm not familiar with the exact details of the DB design but as I know the Nuffield/Leyland design tends to starve the thrust bearing of lubricant, I wondered if this might be something worth trying. It's a nuisance to have to keep another gun charged with oil, but then again it's a nuisance to follow the recommended Leyland procedure of jacking the weight off the front wheels to encourage the grease to go to the bottom.

The 990 had a twin CAV diesel filter like many of the Leylands, or at least I thought it was. It transpires that the DB filters are in series so the 'first' one does all the work which is reflected in the service schedule requiring this one to be changed far more frequently. It has always been my understanding that the Leyland filters are in parallel which seems sensible and I can see no logic in piping them in series, not without some elaborate pressure drop sensing arrangement and indicator system at any rate. On the other hand I cannot believe DB would have done this without some reason.

Regards


Dixie normous
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Re: Thoughts from Meltham

Post by Dixie normous »

Interesting thoughts on the kingpin lube, I know of a David Brown owner who mixes oil and grease together for the kingpins as a small amount of wear seems to let the oil run out too quickly. Mixing it makes it thick enough to stay in place but thin enough to flow right to the bottom.
As for the fuel filters, i was always under the impression that when filters were run in series they were designed to have a primary and secondary filter with different micron ratings. The primary one dealing with large particles and water, the secondary taking out the fine particles. I agree that it makes no real sense to have 2 filters of the same rating flowing in series, maybe its just easier and more cost effective to do it, unless the second filter is simply just there as a 'safety net' in case of a failure in the first one
John
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Nowtnew
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Re: Thoughts from Meltham

Post by Nowtnew »

I've not checked whether the filter elements are the same for both positions. If they are different as you suggest, then it makes sense.

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Paul
Dixie normous
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Re: Thoughts from Meltham

Post by Dixie normous »

I may be completely wrong, it just seems it would be less bother to put the same filter on both heads. The early Masseys had 2 different grade filters on but they were different types of filter so not interchangable
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Nowtnew
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Re: Thoughts from Meltham

Post by Nowtnew »

I've had a quick dekko at the aftermarket parts spec'd for the 990 fuel filter and it seems the normal CAV 296 is used in both locations as per the Leylands. And of course the aftermarket boys never make mistakes...........

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Dixie normous
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Re: Thoughts from Meltham

Post by Dixie normous »

Lord only knows the answer, Case seem to spec 2 different grade filters for some tractors, also some older Internationals, but as you say, in the aftermarket boys we trust!!
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Majorman
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Re: Thoughts from Meltham

Post by Majorman »

Speaking from my experience with double filters on the Ford "X" Series tractors from 1965 to 1968, both filters were the same in this country. However when the tractors were exported a different, shorter filter and a larger water trap were used in the primary filter position.

On Claas combines like the SF and Matador range (I know, ancient history), the primary filter was a felt type and the secondary a paper cartridge.
Kind Regards,
Brian
Dixie normous
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Re: Thoughts from Meltham

Post by Dixie normous »

Maybe it was thought a finer primary filter and water trap were required in dustier or more humid climates than the UK, but here having 2 filters of the same grade was adequate, who knows?
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