Powersteering pump on a 990 Sel

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farbrorbrun
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Location: Sweden

Powersteering pump on a 990 Sel

Post by farbrorbrun » Mon Jul 28, 2014 5:59 pm

Have a David Brown 990 Selectamatic from 1971. Motor is stamped 449001
On the tractor is a power steering pump with separate oil tank. According to the "Official IH online party list" it is named K918993 subsequently replaced with K948432 or K957318.

Anyone knows where to buy a replacement pump for this?

Anyone knows if the motor mount, gear etc fits so that after conversion and removal of the separate oil tank I can mount one with integral oil tank? Like the K957318?

JamesF
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RE: Powersteering pump on a 990 Sel

Post by JamesF » Mon Jul 28, 2014 6:08 pm

I think it was the early power assisted steering systems that used the pump with the separate oil reservoir. From what iv seen the tractors fitted with full power steering rather than assisted steering had the pump and reservoir in one. It may be possible to change the pump with some re routing/altering of hoses and associated pipe work. Alternatively you could go for full power steering assuming you can find parts ok in your area.

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farbrorbrun
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RE: Powersteering pump on a 990 Sel

Post by farbrorbrun » Mon Jul 28, 2014 6:33 pm

thanks for the reply. There is a power steering with orbitrol and longitudinally installed hydraulic piston but as I said a pump with separate oil tank. It may well be that the former have converted from assisted servo

Guest

RE: Powersteering pump on a 990 Sel

Post by Guest » Mon Jul 28, 2014 7:27 pm

The type of pump used was a Plessey pump. It would be a mammoth job in changing to full hydrostatic steering, firstly you'd need to find all the parts and then it would be questionable weather they would fit, especially the column and the front engine plate would have to be changed as well. You don't really say what your problems are with your present steering, we may be able to better help if you explain and tell us a bit more.

John_Allen
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RE: Powersteering pump on a 990 Sel

Post by John_Allen » Mon Jul 28, 2014 7:58 pm

"There is a power steering with orbitrol and longditudinal installed hydraulic piston"

I suspect that the piston means it's got a side-mounted ram and, with the orbitrol, is a hydrostatic steering system!

It may be easier and cheaper to find a used pump with the combined tank on eBay (I seem to think that it would be the same fitting on 1971 tractor (especially if it is a synchromesh gearbox). The pipes may need adapting, but a hydraulic supplier should be able to make them for you.

However, eBay has this:

http://www.ebay.co.uk/itm/David-Brown-H ... 0868658732

I did a search on Google for the 948432 number and found that one!

Strangely, I didn't find it too difficult to change from PAS to hydrostatic steering on my 995!! OK, it was a bit of a pain to sort hoses and steering column, but otherwise, it was straight forward (and not cheap!)
Last edited by John_Allen on Tue Jul 29, 2014 9:53 am, edited 1 time in total.

JamesF
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RE: Powersteering pump on a 990 Sel

Post by JamesF » Mon Jul 28, 2014 9:17 pm

There was a full hydrostatic power steering kit available which could be fitted to upgrade from manual steering. The same kit can be used if you can find it to replace the pas system. We have this full hydrostatic upgrade on our 1200.

Engine backplate does not need changing , there is a cover plate under the dynamo/alternator. This us removed and the steering pump fits here.

You gave to be careful of the corse or fine splined timing gears depending on which you have. The gear on the pump needs to math the rest of the timing gears.

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ollek
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RE: Powersteering pump on a 990 Sel

Post by ollek » Tue Jul 29, 2014 8:22 am

The first hydrostatic steering's in these tractors had the pump and the oil reservoir separate, as was the case for power assisted steering. The OP poster have told that he has a steering with an Orbitrol, and this is then Hydrostatic steering, not power assisted steering. The thing OP wants to know is, where from he can get a new pump and if it is possible to fit a pump with integrated oil reservoir. Some fitments on the right hand side on the engine can interfere with the later pump / reservoir system. It is also important to know, that the older 990 tractors had a different setup of timing gears. The first 990 tractors had casted gears and the later ones steel gears. These gears can not be mixed as there is more teeth in the steel gears than in the cast gears.

JamesF
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RE: Powersteering pump on a 990 Sel

Post by JamesF » Tue Jul 29, 2014 9:31 am

You should be able to fit the combined oil pump and reservoir to the tractor. It will require some altering of pipe work. The later pump shouldn't interfere with anything down the side of the engine. When we fitted it to our 1200 we had to turn the the top half of the lift pump body so the fuel line cleared the pump. If you look at later tractors you will see this was done there also.

As I and ollek have said it is important to observe the type of timing gear and make sure the gear on the pump corresponds to the rest of the timing gears.

I think the original type pump is also still available. The later pump is readily available in the uk from Barcley Williams and the like. I'm not sure where in Sweden to get a pump from but Db parts suppliers and eBay sellers will post worldwide.

Guest

RE: Powersteering pump on a 990 Sel

Post by Guest » Tue Jul 29, 2014 9:34 am

Even on the later models the depth of the timing gears are different also and fitment depends on the depth of the timing cover. Both power assisted and fully hydrostatic steering employed an orbital unit, the difference was in the pump and the method in which they were mounted and driven.

John_Allen
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RE: Powersteering pump on a 990 Sel

Post by John_Allen » Tue Jul 29, 2014 9:52 am

Methinks someone isn't awake yet - there was a steering box with PAS and an Orbitrol with Hydrostatic.

The link I posted for eBay is for an earlier pump (Ollek is right - early ones did have a separate tank) and I expect that there are serviceable "combined" pumps available second hand, but there will be worn ones too - it's the risk you take with eBay (or a breaker).

If the sellers won't post to Sweden, perhaps it's worth contacting Barcley Williams:

http://www.barcleywilliams.co.uk/

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ollek
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RE: Powersteering pump on a 990 Sel

Post by ollek » Tue Jul 29, 2014 11:05 am

A power assisted steering DOES NOT have a Orbitrol valve, only hydrostatic steering has. There is nothing called "full hydrostatic steering", it is hydrostatic or not hydrostatic (PAS).

JamesF
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RE: Powersteering pump on a 990 Sel

Post by JamesF » Tue Jul 29, 2014 11:23 am

There is power assisted steering which still relies on some mechanical effort from the driver or full power where by the driver only has to turn the orbitrol.

There is no orbitrol in the pas system, the valve is in the steering ram on a pas system.

The provision for mounting the pump is there. No point trying to claim it's not

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ollek
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RE: Powersteering pump on a 990 Sel

Post by ollek » Tue Jul 29, 2014 3:51 pm

If someone is interested. The timing gear cover was the same on all 990 tractors with 449 engine. There was no change in the depth of the timing cover and the old and new timing gears were directly interchangeable, provided that the whole set was changed. This was because of the amount of teeth on the gears, not the "depth" (thickness) of the gears. The steel gears came into production at engine serial number 24733. And then the mounting of the pump. Both pumps(separate oil container or integrated oil container) were mounted with two bolts onto the rear face of the carrier plate and they were gear driven from the timing gears. No change was made in this setup during the life of the 449 engine.

JamesF
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RE: Powersteering pump on a 990 Sel

Post by JamesF » Tue Jul 29, 2014 6:39 pm

Thanks ollek, I'd about given up on this one!!

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oily
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RE: Powersteering pump on a 990 Sel

Post by oily » Tue Jul 29, 2014 9:30 pm

i have a brand new one ex doncaster stock for sale

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