New memeber needs hydraulic advice

20 20 · Apr 24, 2009

Hi all, been wondering around the forum for yrs now just never joined, not sure why????????

My question is about hydraulics. I just came across a mini jcb 8015 excavator that I added a hydraulic thumb to. It had male and female aux coupler fittings so I just piped into them. I can get great pressure to close the thumb but I can not get the thumb to go back into the upright position. If I hold the lever and manually lift up on the thumb it will go back up. I believe this may be a single way valve, how would I get pressure to open the thumb?

Thanks for any advice.

I have made mechanical thumbs but this is the 1st hydraulic one I've tackled. I can do some basic hydraulic hookups but am lost after that.

LD1 · Apr 24, 2009

Pics would be helpful.

dfkrug · Apr 24, 2009

20 20 said:
I believe this may be a single way valve, how would I get pressure to open the thumb?

It could also be a motor control valve, intended for use with a hyd auger,
or even a concrete breaker. I don't know why a single-acting valve
would be controlling your AUX circuit. You need a DA valve for the thumb.

kennyd · Apr 24, 2009

dfkrug said:
It could also be a motor control valve, intended for use with a hyd auger,
or even a concrete breaker. I don't know why a single-acting valve
would be controlling your AUX circuit. You need a DA valve for the thumb.

On the JD mini's, there is a rotary switch to control the flow to the AUX circuit. There is probably one on the JCB as well, and is set up for a auger or breaker like you said and is only providing flow one way.

Do you have any manuals 20 20?

20 20 · May 1, 2009

Thanks everyone for the responces I've been busy so this is the 1st time I've had a chance to check answers.

LD1; I don't have any pictures yet.

Dfkrug; I'm thought there would be pressure both ways seeings how the foot petal operates 2 ways?????????

kennyd; I do not have any manuals and am having a real hard time finding any info out about this machine. Everyone I talk to seems to think there is a switch of some sort, some where. I'll have to go over it with a fine tooth comb. it is a pretty plain jane machine, but comes in REAL handy for chores.

dfkrug · May 1, 2009

20 20 said:
Dfkrug; I'm thought there would be pressure both ways seeings how the foot petal operates 2 ways?????????

First, I have no experience with JCB, the 3rd largest equipment maker in
the world. (This British company is only behind Cat and Komatsu in sales, and
assembles TLBs in Georgia.) My experience operating excavators is limited
to Takeuchi, and it is likely that other manufacturers set up their AUX hyd
circuits differently. It seems like your AUX is set up for a hyd breaker.
Breakers use a hyd motor running in only one direction (as far as I know),
and need only ON-OFF control. I would contact JCB and buy an old ops
manual.

The hyd thumb I last used on a Takeuchi used a spring return pedal to
operate it. Press the pedal and it closed; let it go and it opened. I do not
know how common that set up is.

AKfish · May 1, 2009

I've used a Deere, Komatsu and a Bobcat excavator during the past year or so. They were all set up with thumbs and had rocker switches on the joystick.

Never paid much attention to the way to change over to a hydraulic motor setup - jackhammer, etc. 'cause I just wanted to use the thumb.

But, if they're anything like the JD 110TLB - you toggle the Aux hydraulics to go from 2-way intermittant use (thumb) to continuous 1-way flow for a motor. And I have to fiddle with the switches (or check the book) to remember just how to do it everytime....

AKfish