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Jcb 812 lost servo controls

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Topic author
jamesc192
Posts: 32
Joined: Sat May 02, 2009 3:06 pm
Real name: james crossman

Jcb 812 lost servo controls

Post #1 by jamesc192 » Mon Jan 09, 2017 11:45 am

Hi just been cleaning a ditch out and all of a sudden the servo levers stopped working they have gone sloppy with no back pressure to them. The machine still tracks forward and backwards no problem just can't move the boom. I have played with all the switches on the dash but no joy. I remember years ago something similar happened on a hymac 141 I had and there was a solenoid gone behind the seat which contolled the hydraulics could this be the same sort of problem? Any ideas what to look for would be much appreciated many thanks James.
james

jcb 812 powerslide
jcb 3c 111 powertain extradig
jcb 520-4
John Deere 4240s x2
John Deere 3050
John Deere 1640
mb trac 1100 turbo
international 434


essexpete
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Re: Jcb 812 lost servo controls

Post #2 by essexpete » Mon Jan 09, 2017 5:06 pm

I had similar on grey cab 814S but I thought it stopped the track pedals as well. It was the solenoid for the safety switch, burnt the wires in armrest fuse box as well. Short fix was manually wedging the solenoid with a shaped broom handle off-cut against the rear tank. Not long term as no safe cut out.


Topic author
jamesc192
Posts: 32
Joined: Sat May 02, 2009 3:06 pm
Real name: james crossman

Re: Jcb 812 lost servo controls

Post #3 by jamesc192 » Mon Jan 09, 2017 7:00 pm

Many thanks for that I think the dead man on the later models controlled the tracks as well but not on earlier ones as well. Was it one of the solenoids around the valve blocks can you remember which one as there seems to be a few in tgere? Many thanks for your help cheers James
james

jcb 812 powerslide
jcb 3c 111 powertain extradig
jcb 520-4
John Deere 4240s x2
John Deere 3050
John Deere 1640
mb trac 1100 turbo
international 434


essexpete
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Re: Jcb 812 lost servo controls

Post #4 by essexpete » Mon Jan 09, 2017 10:00 pm

The 812 may be a different lay out entirely? Have you got a triple gear pump or the large Variable Displacement + charge pump? (814 is latter) The solenoid in question was one of quite a few dotted about and I cannot for the life of remember how I worked out which was which. Perhaps by following pipework. The one that I jammed in is mounted on the bulkhead between the hyd compartment and engine. It is grouped with at least 2 others (IIRR) pointing fore and aft. I was able to hold in open circuit by piece of said wood wedged to the tank behind.
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Topic author
jamesc192
Posts: 32
Joined: Sat May 02, 2009 3:06 pm
Real name: james crossman

Re: Jcb 812 lost servo controls

Post #5 by jamesc192 » Tue Jan 10, 2017 10:21 am

Thanks so much for that I have the tripple pump and the picture looks a lot different to my arrangement but going to have a crack at fixing it today otherwise I am going to have to call a plant fitter out as the controls stopped with the bucket in the bottom of the ditch which is not ideal once again thanks for the advice really do appreciate it very much.
james

jcb 812 powerslide
jcb 3c 111 powertain extradig
jcb 520-4
John Deere 4240s x2
John Deere 3050
John Deere 1640
mb trac 1100 turbo
international 434


Topic author
jamesc192
Posts: 32
Joined: Sat May 02, 2009 3:06 pm
Real name: james crossman

Re: Jcb 812 lost servo controls

Post #6 by jamesc192 » Tue Jan 10, 2017 1:44 pm

Just a quick update the fuse in the arm rest had blown it looked ok yesterday but I actually tested it today with multimeter and had gone. However the machine moves now but blowing a fuse every couple of minutes now so parked her up disconnected the battery and bit the bullet got a plant fitter/ electrical man coming at end if week to take a look. But thank you very much for the advice much appreciated. James
james

jcb 812 powerslide
jcb 3c 111 powertain extradig
jcb 520-4
John Deere 4240s x2
John Deere 3050
John Deere 1640
mb trac 1100 turbo
international 434


essexpete
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Re: Jcb 812 lost servo controls

Post #7 by essexpete » Tue Jan 10, 2017 8:20 pm

Could be the solenoid damaged but I suppose it could also be a damaged wire. There is also a relay somewhere but FKW.


Topic author
jamesc192
Posts: 32
Joined: Sat May 02, 2009 3:06 pm
Real name: james crossman

Re: Jcb 812 lost servo controls

Post #8 by jamesc192 » Wed Jan 11, 2017 10:13 am

Thanks for that I am ok with mechanical stuff but me and electrics just don't mix so hopefully this guy that's coming can sort it have used him before and he is very good. Thanks for the pointers tho. James
james

jcb 812 powerslide
jcb 3c 111 powertain extradig
jcb 520-4
John Deere 4240s x2
John Deere 3050
John Deere 1640
mb trac 1100 turbo
international 434


Topic author
jamesc192
Posts: 32
Joined: Sat May 02, 2009 3:06 pm
Real name: james crossman

Re: Jcb 812 lost servo controls

Post #9 by jamesc192 » Thu Jan 19, 2017 3:18 pm

Just wondering if anyone knows exactly where the servo isolator solenoid would be it is an earlier type machine 1988 with the tripple gear pump so slightly different layout than on the picture that essexpete very kindly uploaded to this post. Thanks
james

jcb 812 powerslide
jcb 3c 111 powertain extradig
jcb 520-4
John Deere 4240s x2
John Deere 3050
John Deere 1640
mb trac 1100 turbo
international 434


essexpete
Posts: 2323
Joined: Fri Jul 13, 2007 12:43 am
Real name: essexpete
Has thanked: 285 times
Been thanked: 195 times

Re: Jcb 812 lost servo controls

Post #10 by essexpete » Thu Jan 19, 2017 9:19 pm

Sorry I cant't help with location but how many solenoids has your machine? If you unplug carefully one at a time you should be able to work out which one it is (between blowing fuses!)


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