Case/David Brown 990 selectamatic hydraulic question

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singletree
Posts: 10
Joined: Sat Aug 17, 2019 1:44 pm
Location: United States

Case/David Brown 990 selectamatic hydraulic question

Post by singletree » Sat Aug 31, 2019 10:24 pm

Hello, I am a new member. I am presently working on a Case 990/David Brown. When I purchased the tractor it had not been in use for several years. The tractor sat idle out in the open, exposed to all weather conditions. When I started working on it the first thing that I done was to get the engine running. When I tried the hydraulics nothing would work. I checked the hydraulic oil and it appeared to have water in it. I drained the oil and started to change the hyd filter, that is when I found that the suction lift pipe was bent ,due to water freezing the filter. I pulled the suction line back into the correct position, reshaped the filter housing as it had also bulged downward due to the expansion of the ice . Then I installed a new filter and filled the tractor with hydraulic oil. When I tried the hydraulics the lift arms would not work. I then removed the PTO cover and discovered that the hydraulic pump was busted. I removed the pump and the removed the cover/mounting plate so that I could look at the hydraulic pipes that are inside the axle housing. 7. The pipes were not bulged or split in so much as I could tell. However the pump discharge/pressure pipe was loose, I could move it about freely by the end that connects to the pump. I followed the pressure pipe to the bottom of a plate that mounts under the selector valve. That is where I am stuck. I cannot tell how the pipe is connected to the plate, the connection is inside of the axle housing just to the left of the control valve, if you are standing at the back of the tractor. I cannot see the point of connection. It feels as though it would have an O-ring but, I do not understand the way it can be freely moved on the end that mounts into the pump. Would it be OK to leave it as- is ?
If there is anyone that is familiar with how this connection is made and, how to disconnect the pipe. I would appreciate any information that would help me resolve this situation. Thanks for any help, Steve

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ollek
Posts: 3815
Joined: Tue Apr 10, 2012 1:20 pm
Location: South West Finland

Re: Case/David Brown 990 selectamatic hydraulic question

Post by ollek » Sun Sep 01, 2019 12:29 pm

I hope you did not fill the transmission with plain hydraulic oil. You MUST use transmission/hydraulic oil (UTTO or SUTTO) or transmission brake down will be the result. Have you checked that the by-pass valve and the hold valve are free to move in the bores and have you checked that the spool valve is moving up and down approx. 2,5 mm when you move the main control lever from full lower to full lift? The following link shows how the pipes are secured to the rear axle https://partstore.caseih.com/us/parts-s ... 7ar1289500 The locating plate (ref 24) keeps all 3 pipes in position. Your tractor has a different setup on top of the rear axle. There is no connector plate (ref 26) but a base plate (ref 13) as in the following link https://partstore.caseih.com/us/parts-s ... 7ar1292276 The double acting valve is fitted on top of the based plate and you will have to remove the valves and the base plate in order to get to the locating late. I do not think you will gain anything by removing the plate. Please keep in mind that most tractors with a problem with the 3-point hitch not lifting, have one or all of the above mentioned valves sticking.

singletree
Posts: 10
Joined: Sat Aug 17, 2019 1:44 pm
Location: United States

Re: Case/David Brown 990 selectamatic hydraulic question

Post by singletree » Sun Sep 01, 2019 5:36 pm

Ollek, Thank You very much for responding to my post. Yes I have removed the hold and bypass valves, they were both free in their movement and the orfices and screens were clear. Had just a small amount of debris in the screen, can't remember which valve but, I cleaned it, other than that both valves function freely. Yes the spool seems to be working as it should . I removed the small cover plate from the top of the axle housing , I then observed the movement of the spool while working the lever that raises or lowers the lift arms, the spool raises and lowers to seat against the valve body . My main concern is the movement of the pressure /discharge line after removing it from the pump and the pump mounting plate. It is as though the pressure line almost swings freely. Is this normal? You commented that you do not think that there is a problem where the pressure line connects to the plate located under the remote valve. Can you describe how the pressure line connects to that plate? Can I access the end of the line after removing the selector valve? I did in fact use hydraulic oil that I purchased at a tractor supply store. I purchased this because it was inexpensive, I do not intend to use the tractor with it, I was only using it to flush out the old residue from the system. I will then drain it out and replace it with 10 W 30 non detergent. I am almost glad the old pump froze and busted, as that may have prevented pumping/circulating more particulate through the valves. Thank You so much, Steve

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ollek
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Joined: Tue Apr 10, 2012 1:20 pm
Location: South West Finland

Re: Case/David Brown 990 selectamatic hydraulic question

Post by ollek » Sun Sep 01, 2019 7:06 pm

I was almost sure that you would understand the setup by looking at the line drawing I sent in the link. The 3 pipes are going trough drillings in the rear axle and the pipes are kept in place by the locating plate and the plate is fastened to the rear axle with some screws. The location plate slides into groves in the pipes and this locks the pipes so that they can not move up or down but the pipes can still rotate in the drillings. At the top end of the pipes there are O-rings that seals the pipes against the base plate. You said you will use "10 W 30 non detergent". What do you mean by "non detergent? The SAE figure 10W-30 is the viscosity of the oil and in addition to this the oil must fulfil API GL-4 gear box oil classification. I have already said, use UTTO or SUTTO oil with a viscosity of 10W-30.

singletree
Posts: 10
Joined: Sat Aug 17, 2019 1:44 pm
Location: United States

Re: Case/David Brown 990 selectamatic hydraulic question

Post by singletree » Sun Sep 01, 2019 8:50 pm

Ollek, Yes I will be sure to use the proper oil for the transmission / hydraulic system. Concerning the links to the parts diagram that you sent me. I have inserted my hand up inside of the axle housing but I cannot feel the # 25 " locating plate " that is shown in the diagram / for holding the hydraulic line in place. I fully understand the diagram but, how can I gain access to the locating plate in order to replace the o-rings ? Thank you, Steve

singletree
Posts: 10
Joined: Sat Aug 17, 2019 1:44 pm
Location: United States

Re: Case/David Brown 990 selectamatic hydraulic question

Post by singletree » Sun Sep 01, 2019 9:25 pm

Ollek, Thank You for your assistance. I will pull the selector valve and the plate beneath it tomorrow morning , I will then communicate with you. Thank You , Steve

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