Hydraulic issues with DB885 lift

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nathanialbumpo
Posts: 6
Joined: Wed Oct 03, 2018 7:18 pm
Location: USA

Hydraulic issues with DB885 lift

Post by nathanialbumpo » Sat May 30, 2020 3:36 am

Okay, I have a 1973 885 selectamatic, I can't get the rear lift to raise. I can pick it up while the engine is running and there is no resistance at all.
I did the normal things, I flushed the transmission cavity, changed the filter, removed the Valve Body, cleaned the by-pass valve, hold valve, hold relief valve and the spool valve. everything moves freely.
It has a factory mounted double acting valve and a power beyond block mounted on top of it. This is mounted next to the selector control. I get pressure to this valve and beyond so I assume the pump is working. I have removed the ram cylinder manifold and blown air pressure into the ram cylinder hydraulic supply line, I do not hear air leaking and in fact I a blowback of air when I remove nozzle. I assume the supply pipe is okay.
I get oil flow out of lube tubes, I have removed both the by-pass and hold spools and ran the engine to observe oil flow into by-pass valve, I only see oil flow if I push the double acting remote valve forward. I have tried activating this valve at the same time I have moved the lift control lever but still nothing.
I did not pull out and clean the latching valve or the non return valve.

It looks like someone had pulled this apart sometime before I bought it, tractor runs great, I replaced both clutch plates, PTO works, tried to restore everything to as built condition.

I also own a 990A, love the tractor, both are built like a brick ************ house.
Thank you in advance for any help, I have also read and followed Alan Kellett articles, but I am still stuck.

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ollek
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Location: South West Finland

Re: Hydraulic issues with DB885 lift

Post by ollek » Sat May 30, 2020 4:38 am

Lets start with the most common fault made by persons who strips down the system without the knowlage needed to but it back correctly. If you got the tractor with a non operational 3-point hitch, then you will have to start from the beginning and check and correct any settings that are not correct. First of all you will have to remove the valve chest and start to do all adjustments correctly and in the stipulated order as you put the system back. All adjustments are shown in the following link and be spot on when you perform the adjustments http://dbtc.co.uk/index.php/information ... lic-system I would not be amazed if the second adjustment, the spool valve movement, is made incorrectly as this is the most critical adjustment and must be done absolutely correctly and with a accuracy of one thousends of an inch (1/1000"). The link also includes some informations about the Selectamatic hydrauliuc system and fault finding. All this is good reading for anyone new to the system.

ALANJ
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Location: Co. Durham

Re: Hydraulic issues with DB885 lift

Post by ALANJ » Sun May 31, 2020 7:34 am

Q- Having followed the checklist, at what point did things go wrong ?
As Ollek says, ,checking the settings is vital, especially the Group 3 with the quadrant control rod done first as maladjustment here is a common problem.
I would also suggest removing the access plate above the valve chest and place your finger atop the spool valve and cycle the quadrant lever.The spool valve should move up and down approx 100 thou. If not the spool is seized in the drop position and/ or the Groups 1,2, and 3 settings need checking / adjusting.
Seized latching or non return valves will not cause the problem. Burst high pressure pipes could but this failure is remote.
Finally , and first of all, with engine running ,try lifting the link arms with the selector in Ext/TCU and push the quadrant lever fully forward into max TCU .This takes the spool valve out of the circuit.
Hope this helps, come back anytime. Alan K.

Autotech
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Joined: Fri Jun 19, 2020 8:21 pm
Location: Uk

Re: Hydraulic issues with DB885 lift

Post by Autotech » Tue Jun 30, 2020 10:04 pm

I have a odd fault on a 780 with no arm lift in normal circumstances .. if I set to tcu and push quadrant lever to lower the arms raise but with no power , will lift a person only stood on arms .. I have cleaned valves under plate next to camels hump .. I have new filter and oil fitted , hydraullic ,, I have removed the 3 way valve and cleaned it it’s ok .. there is next to no oil supply to this valve engine running , but there is an oil supply to camels hump an visibly can see oil squirting out of valve chest via tin plate removed below tcu lever oil is squirting towards the offside wheel .. . The arms lift and hold under air pressure . Does anyone have any ideas ie stuck valve on block or split pipe ?. Also odd with 3 way valve removed. Engine running Oil to camels hump is apparent but none to lower or closer supply from pump to 3 way valve. Just seems odd .. where should I start to dismantle valve block or pto and pump ? Many thanks

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ollek
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Location: South West Finland

Re: Hydraulic issues with DB885 lift

Post by ollek » Wed Jul 01, 2020 2:50 am

First of all, do not use others topics, but open up a ne topic for your problem. Then, if the hitch will lift with low power when you push the lever forward, the you have the TCU function selected and the system is functioning correctly in TCU. Select "Height" control for normal use. There is a oil supply to the 3-way valve only when the system is lifting, no oil is directed to the 3-way valve when the system is in hold or lowering. Does the spool valve move completely down when the lever is in lift position? Have you cleaned the nylon scteen and the restrictor in the by-pass valve? Please see the following link https://partstore.caseih.com/us/parts-s ... 03ar292683 You will also need a Operators Manual for your tractor, as all this, and much more, is explained in the manual. Obtain a manual from the following link http://www.davidbrownparts.com/Books%20 ... nuals.html

Autotech
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Joined: Fri Jun 19, 2020 8:21 pm
Location: Uk

Re: Hydraulic issues with DB885 lift

Post by Autotech » Wed Jul 01, 2020 1:40 pm

many thanks for the reply i didnt know how to start my own thread... there wasnt a nylon gause on the valve but it was origonally stuck .. how is the spool valve movement visible does it move out from underneith the valve body and yes i bought the operators hand book many thanks

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ollek
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Re: Hydraulic issues with DB885 lift

Post by ollek » Wed Jul 01, 2020 3:48 pm

There is two nuts on top of the spool valve, visable to the rear from the by-pass and hold valves.

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db2d
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Location: Monmouthshire

Re: Hydraulic issues with DB885 lift

Post by db2d » Wed Jul 01, 2020 4:55 pm

Do not slacken or adjust the nuts on the spool valve. The adjustment setting is critical.

Autotech
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Joined: Fri Jun 19, 2020 8:21 pm
Location: Uk

Re: Hydraulic issues with DB885 lift

Post by Autotech » Wed Jul 01, 2020 5:53 pm

thank you for the info i think you mean i have to remove the rear assembly to which the tcu / hight/ lowering lever is attatched is this correct ? i see a lot of oil pooling on the rear case that has the tin cover . and visibility is poor . so am i correct that i need to remove lifting arms and cross axle assembly to have a open visual inspection of the valve chest body you noted ? i have never worked on hydraulics before apart from external pumps and pipes on motor vehicles many thanks ..

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ollek
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Location: South West Finland

Re: Hydraulic issues with DB885 lift

Post by ollek » Wed Jul 01, 2020 8:06 pm

No, I have not asked you to remove anything heavy at this stage. You can see the two nuts trough the opening for the by-pass and hold valves, and the nuts are on top of the valve chest. There is a small cover on top of the rear axle to the rear of the control lever. The dump valve goes trough this cover (if the tractor has a dump valve), and you can see the valves after removing this cover. You have said that you have had the by-pass and hold valves removed so why cant you bend your head a little bit and look to the rear from the hold and by-pass valves trough the opening. Do not start the engine when you check the movement of the spool valve. In section Hydraulic section (V) for 885, 990, 995. 996 you will find picture number 28 on page 24 in the following link https://drive.google.com/drive/folders/ ... Dh6M2k0bVk

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cobbadog
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Re: Hydraulic issues with DB885 lift

Post by cobbadog » Thu Jul 02, 2020 6:45 am

On the Home Page of this Forum, at the top of the page is a box with New Topic or similar, click on that and you can start a new thread. As suggested, start a new thread for each different issue so it is not confusing as to which issue it is you would like help with.
The next thing that also helps a lot is posting pictures to help identify what it is you are talking about. As this is a world wide Forum different Countries call the same item different names which also is confusing. Pictures must be compressed to be posted and to attach a picture at the bottom of your reply there is a box called 'Attachments', click on that and attach your compressed images work on 3 images at a time to post.

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