JCB 8015 arm not lifting

[V8Druid]

The blade, tracking and slew all work Ok. I’ve not ventured into the valve block as yet.
initially we tried to tighten the fan belt by accessing from behind seat, but gave in and decided to move to a clean floor where we could access underneath. That is when we started her up and the hand controls lost power and the jib arm would not lift. Did test on dead man’s handle and followed power all the way to coil. Removed coil and tested separately. That is what we have done so far.

by slew I assume you mean the offset for the boom as opposed to the slew for the whole upper structure ? ... the slew is a servo operated service .. the off set is not servo controlled

 

[Moog]

Yes, offset for the boom works ok from the foot control. The cab does not rotate from hand controls.

 

[CPS]

Do these have a separate servo pump or feed of the main pressure @jd6820? I think its time for a set of gauges on it

 

[V8Druid]

Do these have a separate servo pump or feed of the main pressure @jd6820? I think its time for a set of gauges on it

that valve block is a pressure reducer from all three pumps Aiden drops it to servo levels by an RV ... the schematic is further back in this thread

there are two Stauf connectors on the valve block - one for main and one for servo pressure measurements - see the pic I put up earlier

 

[jd6820]

Do these have a separate servo pump or feed of the main pressure @jd6820? I think its time for a set of gauges on it

As V8druid states the valve block is used the regulate pump pressure down to servo pressure and there are test ports on said block. I can have a look for specs unless V8 has them in his manual?

 

[V8Druid]

As V8druid states the valve block is used the regulate pump pressure down to servo pressure and there are test ports on said block. I can have a look for specs unless V8 has them in his manual?

will have a look later ..... trying to evict 4 screaming kids and their parents ATM

 

[bobthebuilder]

The blade, tracking and slew all work Ok. I’ve not ventured into the valve block as yet.
initially we tried to tighten the fan belt by accessing from behind seat, but gave in and decided to move to a clean floor where we could access underneath. That is when we started her up and the hand controls lost power and the jib arm would not lift. Did test on dead man’s handle and followed power all the way to coil. Removed coil and tested separately. That is what we have done so far.

you havnt broken /dislodged a wire whilst try to tighten fan belt ,as it seems to have started since that event

 

[Moog]

you havnt broken /dislodged a wire whilst try to tighten fan belt ,as it seems to have started since that event

That’s what my friend keeps telling me, but I’ve looked again and again and cannot see any wire that has come adrift. What you say makes sense but nothing is obviously loose. I think I am going check the earth connections on bodywork before i go any further with the valve block.

 

[jd6820]

That’s what my friend keeps telling me, but I’ve looked again and again and cannot see any wire that has come adrift. What you say makes sense but nothing is obviously loose. I think I am going check the earth connections on bodywork before i go any further with the valve block.

If we break the problem down into its simplest form. As long as the gear pumps are rotating (being driven) which they are (as the non pilot controlled hydraulics work) then we need to isolate the fault with the pilot circuit, first by deducing is the fault electrical or mechanical. The electrics can quite easily be eliminated. If the solenoid is provided with power, sufficient that when coil is removed off the valve it will grip an allen key or screwdriver in the centre then we know the electrics are fine. The fault is then mechanical. Next step would be to plug gauges into the pressure regulating block and observe system and pilot pressure. If this isn't possible then system pressure can be forced by deadheading a circuit (blade probably best) and see if at the same time you gain any control of the arm. If the check valves are faulty in the block, forcing system pressure on one pump moves any loose balls hopefully against the low pressure flow coming from the other pumps and hopefully oil into the block itself and thus onto the pilot circuit. If deadheading the circuit doesn't yield such results then the solenoid valve itself (not the coil) is potentially jammed. As this ultimately allows oil flow (after regulation to correct pressure) into the pilot circuit and up to the joysticks. As I'm guessing you have no guages some of this diagnosis is going to be trial and error. If you weren't three hours away I'd jump in my van and show you how to diagnose and fix it.

 

[bobthebuilder]

That’s what my friend keeps telling me, but I’ve looked again and again and cannot see any wire that has come adrift. What you say makes sense but nothing is obviously loose. I think I am going check the earth connections on bodywork before i go any further with the valve block.

there isnt some sort of imobilsler type of thing on it ?

 

[CPS]

If we break the problem down into its simplest form. As long as the gear pumps are rotating (being driven) which they are (as the non pilot controlled hydraulics work) then we need to isolate the fault with the pilot circuit, first by deducing is the fault electrical or mechanical. The electrics can quite easily be eliminated. If the solenoid is provided with power, sufficient that when coil is removed off the valve it will grip an allen key or screwdriver in the centre then we know the electrics are fine. The fault is then mechanical. Next step would be to plug gauges into the pressure regulating block and observe system and pilot pressure. If this isn't possible then system pressure can be forced by deadheading a circuit (blade probably best) and see if at the same time you gain any control of the arm. If the check valves are faulty in the block, forcing system pressure on one pump moves any loose balls hopefully against the low pressure flow coming from the other pumps and hopefully oil into the block itself and thus onto the pilot circuit. If deadheading the circuit doesn't yield such results then the solenoid valve itself (not the coil) is potentially jammed. As this ultimately allows oil flow (after regulation to correct pressure) into the pilot circuit and up to the joysticks. As I'm guessing you have no guages some of this diagnosis is going to be trial and error. If you weren't three hours away I'd jump in my van and show you how to diagnose and fix it.

What he said ....... only he said it better

 

[V8Druid]

there isnt some sort of imobilsler type of thing on it ?

unlikely to just immobilise the servo circuit though Bob (although could easily be achieved - have mentioned a Hella type 'key' many times on here)

@Moog is the seat base plate still out or back in ??? haven't trapped/cut a wire removing/replacing it???

 

[V8Druid]

That’s what my friend keeps telling me, but I’ve looked again and again and cannot see any wire that has come adrift. What you say makes sense but nothing is obviously loose. I think I am going check the earth connections on bodywork before i go any further with the valve block.

the dead man circuit's cables should all be to the left side of the m/c / cab ... can't see why they would go anywhere near the other side of the engine bay - dead man switch under/in left arm rest .. solenoid control and servo pressure reg. valve block in the left side of the engine bay .. maybe 6-8" away from the switch under and behind it.
have you tested the solenoid, (with it off the valve and a steel rod in it), to be energised, by the dead man circuit, actually connected in circuit, with the m/c / switch - engine running??
if it does energise it's either (a) not electrical or (b) weak solenoid pull

 

[Moog]

If we break the problem down into its simplest form. As long as the gear pumps are rotating (being driven) which they are (as the non pilot controlled hydraulics work) then we need to isolate the fault with the pilot circuit, first by deducing is the fault electrical or mechanical. The electrics can quite easily be eliminated. If the solenoid is provided with power, sufficient that when coil is removed off the valve it will grip an allen key or screwdriver in the centre then we know the electrics are fine. The fault is then mechanical. Next step would be to plug gauges into the pressure regulating block and observe system and pilot pressure. If this isn't possible then system pressure can be forced by deadheading a circuit (blade probably best) and see if at the same time you gain any control of the arm. If the check valves are faulty in the block, forcing system pressure on one pump moves any loose balls hopefully against the low pressure flow coming from the other pumps and hopefully oil into the block itself and thus onto the pilot circuit. If deadheading the circuit doesn't yield such results then the solenoid valve itself (not the coil) is potentially jammed. As this ultimately allows oil flow (after regulation to correct pressure) into the pilot circuit and up to the joysticks. As I'm guessing you have no guages some of this diagnosis is going to be trial and error. If you weren't three hours away I'd jump in my van and show you how to diagnose and fix it.

Thanks mate, I really appreciate the offer of help if we were closer - you’re a star.. I’m trying to digest all the info you have written. Yep, I have no guages here, but I could see if could borrow some next week if we are still struggling. how do I deadhead a circuit? Disconnecting the pipe and putting in a blank? would I follow the oil pipes back from the blade to the pump?
just answering V8Druid Yep, tested the coil (out of the valve) with engine running and dead man’s handle worked energising screwdriver, then releasing. Not sure why the switch wire goes under engine etc, seems a convoluted route.

 

[jd6820]

Thanks mate, I really appreciate the offer of help if we were closer - you’re a star.. I’m trying to digest all the info you have written. Yep, I have no guages here, but I could see if could borrow some next week if we are still struggling. how do I deadhead a circuit? Disconnecting the pipe and putting in a blank? would I follow the oil pipes back from the blade to the pump?
just answering V8Druid Yep, tested the coil (out of the valve) with engine running and dead man’s handle worked energising screwdriver, then releasing. Not sure why the switch wire goes under engine etc, seems a convoluted route.

Deadhead means operate the blade ram to the end of its stroke (lift blade up) and hold it in this position whilst trying the joystick.

 

[Moog]

Deadhead means operate the blade ram to the end of its stroke (lift blade up) and hold it in this position whilst trying the joystick.

unfortunately no luck - did deadhead on the blade a few times, but no response from the hand controls - doh!
Ive checked for trapped or broken wires by the seat base which is still out, but there are no wires in that area. The dead man’s switch wire follows the hand control cables out of the left hand side within a plastic pipe.

 

[V8Druid]

unfortunately no luck - did deadhead on the blade a few times, but no response from the hand controls - doh!
Ive checked for trapped or broken wires by the seat base which is still out, but there are no wires in that area. The dead man’s switch wire follows the hand control cables out of the left hand side within a plastic pipe.

silly Q, but you did have the deadman down and the solenoid in place, connected to circuit? -
did you try it with a separate 12v supply too ?

 

[CPS]

So, you have had the seat out to tighten the alternator belt right? And it worked beforehand?
Are any other electrics working? Could it be a case of looking in the wrong area? Maybe a wire has been knocked if the alternator? Or around there? Strange if it worked beforehand and not now, has to be related

 

[Moog]

silly Q, but you did have the deadman down and the solenoid in place, connected to circuit? -
did you try it with a separate 12v supply too ?

I’ve tested the solenoid (coil attached) direct to 12v battery, bypassing dead man’s switch - nothing on the hand controls. Also tested coil separately when it is attached to the circuit, lifting and lowering the arm control to activate the dead man’s switch, which magnetised the coil (holding a screwdriver) when the arm control was lowered.

 

[Moog]

So, you have had the seat out to tighten the alternator belt right? And it worked beforehand?
Are any other electrics working? Could it be a case of looking in the wrong area? Maybe a wire has been knocked if the alternator? Or around there? Strange if it worked beforehand and not now, has to be related

Yes, all worked beforehand. Electrics seem ok, they work on ignition, horn, digital console display. There is a connector on the alternator with 2 yellow wires coming off it, which Ive disconnected and reconnected to check for a broken wire. Not sure where those 2 wires go to as they get lost in braiding. I will take a pic and add it here for suggestions