David Brown 900

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David Brown 900

Post by Robert10100 » Fri May 27, 2011 11:21 am

Hi guys,

What are the key features that distinguish a Mk1 900 from a Mk2?

My 900 has an ususual steering arrangement with the radius arm linking a ridiculously complicated assembly in the middle of the tractor to the steering box drop arm. What were they thinking with this steering mechanism at all?!!!

Secondly, it has a 30D style air filter, and a 'David Brown' Cropmaster style badge running down the centre of the grilles. Also, it has a round-sided 30D style chassis supporting the engine. At a guess, I'd say mine is an early example.

Also, a quick question about engine oil filter assemblies and engine blocks: There appear to be three different types of oil filter assemblies on early red David Brown diesel engines up to and including the implematic range:

(i) The tall tower type holder seen on the Cropmaster Diesel, 30D, 25D, 900 etc;

(ii) A round assembly that is interchangable with (i) above and houses a screw in type filter as seen on the 950. This assembly can be bolted off;

(iii) A round style oil fiter casing that screws straight into the engine block, similar to (ii) but that is not interchangble with (i). Which David Brown Implematic models had this type? Thanks.

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RE: David Brown 900

Post by jearl » Fri May 27, 2011 11:58 am

I am not aware of there being a mark 1 or mark 2 in the 900 range ... there was the first series called the H series distinguished by the offset steering wheel and an "open channel" down each side of the engine ... good for tools and rags ... then they produced the J & L series with centralised steering wheel channel closed in ... J was the Livedrive ... L was the non live drive

As for the steering system it was a very poor design and a lot were converted to the system adopted on the 950 ... I have three 900's and I know for certtain that another here in Perth all have the poorly designed sytem ... they still all work OK albeit a bit sloppy ...maybe here in Australia the lighter soils and larger paddocks (fields) didn't put the same stresses on the steering

If you look at the serial number you can compare it to the details on this website and it will give an idea of where your tractor came in the production run

I read somewhere that the 900 was very much an interim tractor between the Cropmasters and the 950 and therefore you find a lot of similarities with parts etc as they used up old stock etc ... the same article also said that just about no two David Brown tractoe were identical of the production line

I'll leave your queries about the oil filters to someone with a better understanding



RE: David Brown 900

Post by Guest » Fri May 27, 2011 3:32 pm

Following on from Julian's post, the first production 900 of 1957 was basically an 'uprated' 30D in as much as the injector pump fitted was a CAV DPA type which gave the tractor through a slightly higher fuel delivery, a little more power. It had the same basic skid unit of the 30D but the innovative main difference was that for the first time on D.B. tractors a one-peice bonnet was fitted and the mudguards were a new design as well. The hydraulics and their operation were the same as that on the 30D. The front casting was slightly thicker than previously and the addition of a 'stud' wasfitted on the right hand side of the casting for stowing the drawbar. Not all the early ones had the 'David Brown' verticle plate on the bar between the grille louvres. The steering system was not very succesful or popular as it's weak point was the stub on which the draglink arm connected on, it had a habit of shearing at the elbow and those thad did survive were forever chewing up the bush and as a consequence if not replaced when detected would cause the stub to shear. There was a later replacement system offered to eliminate these problems of which was fitted as standard on the 1958 900 that adopted the same build as the 950. The engine oil filter and housing was also the same as the 30D but the Cropmaster type washable fibre element was deleted and a paper replaceable element used which did away with the round steel plate on the top in the housing and a domed rubber 'washer' was used in its place which could be re-used several times. The cannister and shorter but larger diameter filter unit was introduced with the 950 and you could also replace the original unit on the 900 (and 30D) with this later unit but you also had to change the cork gasket with the 950 type between the unit and the block as this one had an extra oil hole in it. This later horizontal cannister type filter was fitted to every other model up to 1976 after which all models were fitted with the spin-on type.

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Post by Robert10100 » Sat May 28, 2011 11:27 am

Here is a cannister type filter similar to that of the 950, but where the cannister screws directly into the block as opposed to into a housing which screws onto the block. Which of the Implematic models were fitted with this type of engine?

Also, did the series II DB 900 have the horizontal 'David Brown 900' badge on the top of the front nosecone? The DBTC cutaway 900 has this...Thank you.


Post by Guest » Sat May 28, 2011 2:47 pm

The cannister type you picture was introduced on the first 4 cylinder 880 and 950 Implematic in 1962. The previous pre-Implematic had the same canister but was stood off the block like the 30D and 900, a cross between the two. The 900 horizontal badge on the nose cone was fitted to the later 1958 900.


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Post by WesBrown » Sun May 29, 2011 11:22 pm

My uncle had a 900 from new, a 1958 one. That had the central steering mechanism, I don't remember it being any trouble. Allan T Condie, who has produced lots of books on various British tractors, reckoned this system was for export, but quite a few British 900s have it, I've seen one or two on eBay equipped so.

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oil filter canister

Post by Dewi » Sun May 29, 2011 11:47 pm

Hi, I have a 1961 950 which has the oil filter canister which screws straight onto the block , it also has a round front casting like the 990 is this unusual ?


RE: oil filter canister

Post by Guest » Mon May 30, 2011 8:37 am

Dewi, the front casting has probably been replaced with a later one. It probably has the later 'fabricated' front axle as well. Not unusual for a lot of D.B's of this period having a different front casting, especially on tractors that have or have had front loaders on them. The way to tell is that normally the serial number stamped on will be different than that of the original to the tractor.There are lots of 900's around with 950 front castings.

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Post by Dewi » Mon May 30, 2011 11:30 am

Hi, the round front casting on my 950 must be original as it has the correct serial no stamped on it ,the tractor has a forged axle not the later fabricated one .


Post by Guest » Mon May 30, 2011 1:03 pm

Hmm. The rounded front casting was first fitted to the 850 in 1961 which is basically a 950 on smaller rear wheels. Are you certain that the original numbers on the casting have not been ground out, a 'skin' of weld applied and then ground back to level and re-stamped? The forged front axle was also on the 850. I would very much doubt that this casting is original to the tractor.

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Post by Dewi » Mon May 30, 2011 2:13 pm

Hi, I would say that the front casting is original , it does not show any marks around the serial no. The casting looks like the 990 one, which I believe is deeper than the one on the 850.

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Post by JimCochrane » Mon May 30, 2011 3:20 pm

Your 950 will be correct with the round front casting as this became standard on the 950 after the 990 was introduced.Not as many of this type of 950 as they were nearly the same price as the 990 but had 10hp less.
As far as the 900 goes the original steering was better as it had more lock and a quicker action but suffered more from wear.It was a stupid design for the pivot on the steering arm attached to the axle under the sump.
It was a big course thread not a bush and the thread would wear giving loads of play. Can be very well repaired by machining the thread off and fitting 6005 2rs bearings instead.

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