780 selectamatic loader spool challenge...

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davebirt
Posts: 13
Joined: Tue Jan 01, 2019 11:11 am
Location: somerset

780 selectamatic loader spool challenge...

Post by davebirt » Mon Jan 21, 2019 1:38 pm

Hi all,
Ive just popped on a david brown loader with powered bucket.
(The rear hydraulics work fine)
Ive followed the chaps instructions who i purchased it from (off another 780) and had some new pipes made.
Ive attached a photo of the plumbing.

Lower and raise arms
(selector nob left hand side seat far left, selector knob right hand side set to "TCU" quadrant back into "select")
-Pull lever on lader spooler,
-It lifts (left leaver up)
-Drops (left lever lifted a little)
-left lever down nothing but pump straining.

Bucket
Up(right lever raised) bucked hose jumps bucket stuck
Down (right lever down) bucked hose jumps bucket stuck
Feels like the old can't get back?

Have had the spooler off and tested with air using right hand lever and bucket ram
Up ram out
Down ram in
it worked?

Ive popped it back on same problem?
I have the feeling there needs to be another connection (apart from the flow through from and to the tractor)
Any help most gratefully received please look at the photos.
DB_spooler.jpg
DB_spooler.jpg (214.75 KiB) Viewed 2098 times
out_and_return.jpg
out_and_return.jpg (221.7 KiB) Viewed 2098 times
side view.jpg
side view.jpg (170.52 KiB) Viewed 2095 times

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ollek
Posts: 3863
Joined: Tue Apr 10, 2012 1:20 pm
Location: South West Finland

Re: 780 selectamatic loader spool challenge...

Post by ollek » Mon Jan 21, 2019 6:13 pm

Is your loader equipped with double acting cylinders at the boom and the bucket? If so, then you have missed out the second houses to the cylinders. Double acting cylinders needs two hoses from the loader spool valve and it looks that you have only one hose for the boom lift and one for the bucket control and that the second ports for these functions are plugged. This will put the pump under load when the oil is directed to the plugged outlets at the loader spool valve and the cylinder you wan to use will not move. The supply to the loader spool valve from the 3-way valve (top connector, also called connector 1) and the return to the left hand side on top of the rear axle looks to be OK. Please check that the feed from the 3-way valve is connected to port "P" and the return to port "T" on the loader valve.

davebirt
Posts: 13
Joined: Tue Jan 01, 2019 11:11 am
Location: somerset

Re: 780 selectamatic loader spool challenge...

Post by davebirt » Mon Jan 21, 2019 8:13 pm

Thanks Ollek,

See answers to your questions below:
Is your loader equipped with double acting cylinders at the boom and the bucket?

No, the loader (left hand lever) has 2 rams both single action it's lifted Hydraulically and gravity drop. The bucket has a double acting ram which is connected to the spool block with two hoses (right hand lever as in pic. the pic looks like one hose- see the side view in the pics)

If so, then you have missed out the second houses to the cylinders. I wish i had...

Double acting cylinders needs two hoses from the loader spool valve and it looks that you have only one hose for the boom lift and one for the bucket control

(have one to the loader and two to the bucket- (right hand lever has two hoses see shot 3 in the post)

and that the second ports for these functions are plugged.

This will put the pump under load when the oil is directed to the plugged outlets at the loader spool valve and the cylinder you wan to use will not move.

The supply to the loader spool valve from the 3-way valve (top connector, also called connector 1) and the return to the left hand side on top of the rear axle looks to be OK.

Please check that the feed from the 3-way valve is connected to port "P" and the return to port "T" on the loader valve.
The valve has no "p" or "t" markings it only has an arrow on the surface from left to right which I've assumed indicates direction of flow? Ive tried reversing it and have exactly the same problem

Thankyou for your thoughts Im still keen to hear more!

davebirt
Posts: 13
Joined: Tue Jan 01, 2019 11:11 am
Location: somerset

Re: 780 selectamatic loader spool challenge...

Post by davebirt » Mon Jan 21, 2019 8:33 pm

pic of loader...
loader.jpg
loader.jpg (196 KiB) Viewed 2062 times

SteveCollett
Posts: 583
Joined: Wed Sep 24, 2008 8:17 am
Location: Suffolk

Re: 780 selectamatic loader spool challenge...

Post by SteveCollett » Tue Jan 22, 2019 9:56 am

just a guess
you may have the two spools reversed.
so bucket pipes to go on left hand spool and loader on right, they appear to be giving the symptoms I would expect if you were using the wrong type of valve for each.
worth a try

davebirt
Posts: 13
Joined: Tue Jan 01, 2019 11:11 am
Location: somerset

Re: 780 selectamatic loader spool challenge...

Post by davebirt » Tue Jan 22, 2019 6:54 pm

Many thanks that's the only thing i haven't tried- the spooler was connected to the pipes on the loader when it arrived - the front ram only, the loader (arms) pipe was not connected but was advised it fitted with the one blanked as shown on the shots - I have taken the spooler off and the front ram, connected it up to compressed air and it works as i imagined it would (right hand lever up ram flys forward right hand lever down it rushes back) popped it on the tractor and JAM bucket stops and both pipes jump. Have also disconnected the return flow to the tractor to see if the oil flows through the spooler, it does, i tried the lever for the bucket oil stops bucket stops!
its a real conundrum- But i'll give it a go at swapping the connections as you advise.

Please keep thinking!

davebirt
Posts: 13
Joined: Tue Jan 01, 2019 11:11 am
Location: somerset

Re: 780 selectamatic loader spool challenge...

Post by davebirt » Tue Jan 22, 2019 7:05 pm

The only other thought is that the spool block isn't correct for the loader or the tractor?

SteveCollett
Posts: 583
Joined: Wed Sep 24, 2008 8:17 am
Location: Suffolk

Re: 780 selectamatic loader spool challenge...

Post by SteveCollett » Wed Jan 23, 2019 8:25 am

Very often the original plumbing used the normal lift quadrant and probably a trip bucket.
It was very common to see such conversions using a variety of spools fitted in a similar fashion. I had a veery similar set up on a little 780 I owned at one time. I think the actual DB arrangement was similar

philedge
Posts: 251
Joined: Sun Dec 03, 2006 11:27 am
Location: Chester UK

Re: 780 selectamatic loader spool challenge...

Post by philedge » Wed Jan 23, 2019 1:17 pm

Its definitely a super loader with a powered bucket tip. The spool block looks new, certainly compared to the loader- did the guy you got it from say he had it working?
'66 880 Selectamatic rat.

davebirt
Posts: 13
Joined: Tue Jan 01, 2019 11:11 am
Location: somerset

Re: 780 selectamatic loader spool challenge...

Post by davebirt » Thu Jan 24, 2019 7:56 pm

Yep he said it was working as thee set up i have. Ive cleaned the block and popped on some new fittings, still can't figure out why - but will swap the pipes over and see what happens then- i'm not that hopeful.

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

Re: 780 selectamatic loader spool challenge...

Post by ollek » Fri Jan 25, 2019 10:16 am

The spool for the boom have to be single acting and the spool for the bucket must be double acting. Any other spool configurations will not work correctly. It looks like both spools are double acting, as one outlet is plugged. Plugging a outlet from a double acting spool will put the pump under strain when the oil flow is directed to the plugged outlet.

philedge
Posts: 251
Joined: Sun Dec 03, 2006 11:27 am
Location: Chester UK

Re: 780 selectamatic loader spool challenge...

Post by philedge » Fri Jan 25, 2019 10:53 am

When you have the quadrant lever in the select position you have to hold it against the spring to get full pressure to external equipment such as your loader. If youre not pulling the lever fully back and holding it against the spring you may not be getting enough pressure to get the rams to move. Theres an optional catch to hold the lever back if you dont have one
'66 880 Selectamatic rat.

davebirt
Posts: 13
Joined: Tue Jan 01, 2019 11:11 am
Location: somerset

Re: 780 selectamatic loader spool challenge...

Post by davebirt » Fri Jan 25, 2019 4:42 pm

Thanks chaps ,
Ollek,Ok thank you so that would explain why the boom lifts when the lever is up (and drops with gravity when the lever is up a little, and does nothing but make the pump noise when down) but the bucket is connected to a double acting valve and fights itself, with both lift and lower. (i have tried reversing the connections them- same problem).

Phil, yes the quadrant lever is pulled back against the spring with the selector set to TCU when i'm operating the levers for the loader?

thanks so much for the help and suggestions so far-

I can't understand why the spooler works when run on compressed air (bucket ram tested goes in and out) and not when connected to the oil.
Last edited by davebirt on Fri Jan 25, 2019 4:56 pm, edited 1 time in total.

davebirt
Posts: 13
Joined: Tue Jan 01, 2019 11:11 am
Location: somerset

Re: 780 selectamatic loader spool challenge...

Post by davebirt » Fri Jan 25, 2019 4:51 pm

anyone know of or where i can get my hands on a spooler for loader with single acting boom lift -gravity drop, and a double acting valve for the powered bucket? great if it were a DB.

1952CROPMASTER
Posts: 99
Joined: Thu Dec 15, 2016 12:24 pm
Location: Moncton NB

Re: 780 selectamatic loader spool challenge...

Post by 1952CROPMASTER » Fri Jan 25, 2019 9:20 pm

Did you check inside the Hose or Pipe that you had to replace to see if they were plugged off somewhere.
I have seen a plastic cap inside the hose blocking off the oil Flow
Just a thought

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