Anyone know JCB telehandlers? Steering problems....

[aczlan]

But, I can't for the lift of me find anything that looks like the selector switch or where it should be. There 6 or sow rocker switches on the dash, but they all appear to be for lights.

Looking at: 3-MODE STEER, SWITCH & HARNESS - CONSTRUCTION JCB .520 (LOADALL 520-50, 9802/7820, M754000-) | 777parts.com and picking a plain 520, it looks like it's a rotating knob (item 2), but it doesn't really show where it's physically located:

Aaron Z

 

[bgaidan]

Sounds like it's stuck in both modes, and leads to a hydro locked situation.

Put the rear lines into a bucket and try it.

Plausible.

Why rear lines instead of front? 2-wheel steer would be rear and those are the only ones that are trying to move. My intuition would be to disco the fronts and try to get the rears to move.

 

[bgaidan]

I've never ran a jcb but on a lot of the older new style forklifts the selector is at some combination of behind and under the seat. It always looks like an afterthought until you get to the really new stuff

Looking at: 3-MODE STEER, SWITCH & HARNESS - CONSTRUCTION JCB .520 (LOADALL 520-50, 9802/7820, M754000-) | 777parts.com and picking a plain 520, it looks like it's a rotating knob (item 2), but it doesn't really show where it's physically located:

Aaron Z

I've looked everywhere and don't even see a spot where that could have been.

There is this cluster of wires that are in that pocket down below the steering wheel to the left. Almost looks like a radio in that illustration.

No clue if any of these are important....but I've also seen other "running" machines in auction listings that had the same wires hanging out.

 

[Dethmachinefab]

Plausible.

Why rear lines instead of front? 2-wheel steer would be rear and those are the only ones that are trying to move. My intuition would be to disco the fronts and try to get the rears to move.

Didn't know 2-wheel was rear, was thinking about how my crane is set up.

Sounds like a good first easy diag step.

 

[JD Mark]

Maybe you should ask the seller how his mechanic "died suddenly" before digging too much further.

 

[bgaidan]

Didn't know 2-wheel was rear, was thinking about how my crane is set up.

Sounds like a good first easy diag step.

Yeah, I agree. Gonna dig out some buckets and pig mats and mess with it this afternoon.

Maybe you should ask the seller how his mechanic "died suddenly" before digging too much further.

He might still be trapped under the foot of sludge in the back compartment.

 

[bgaidan]

I'm pretty sure this is the main valve body. At least the front steering hoses lead here. Couldn't trace the back ones yet without laying in a pool of hydraulic fluid, but assuming they lead here too.

I think I found a bootleg copy of the service manual on ebay for $20 so once I verify it covers my serial number, I'll grab that and go to work.




Also, question for the more hydraulically experienced. What would be the purpose of tee-ing off of the lines feeding the rear steer cylinder like this?

 

[bgaidan]

Breaking development!

I started tracing the lines from the cylinders and followed the small lines off the tee on the rear cylinder that I referenced above and found this on above the back of the engine bay.

I tried to see the handbook but realized I don't have one so I just fucked with it. And with it turned 90 degrees so the handle is vertical, I my front steering is now working, but still nothing out of the rear.

I'm assuming the normal position should be the way it is in the pic and I don't yet understand how it works or what the procedure is supposed to be, but it sure would have been nice to know about it last night when we were unloading. Both of the lines off those tees run up to this valve, so I assume when I turn it, it serves as bypass to the rear steer cylinder. So the procedure must be: open valve, center front wheels, close valve and put it in to 2 wheel steer mode.

So why would bypassing the rear cylinder suddenly make the front one start working? Does this add to Dethmachinefab's theory that the front and rear are fighting each other somehow?


I ordered a service manual from some sketchy site from India that was supposed to give me an instant download, but I didn't get the link. So now I'm giving them a couple hours to respond to my e-mail before I accept I got ripped off and try another sketchy site.

 

[ThePanzerFuhrer]

This is the one I have used in the past. They were quick

JCB Manuals PDF | Heavy Equipment Manuals

Explore the comprehensive JCB 930-4 LE Rough Terrain Forklift Parts Manual. Easily locate and order necessary parts with detailed diagrams and part numbers. Includes jcb service manual pdf.

www.heavy-equipmentmanual.com

 

[ScottRS]

So why would bypassing the rear cylinder suddenly make the front one start working? Does this add to Dethmachinefab's theory that the front and rear are fighting each other somehow?

I don't know JCB specifically, but I'm guessing that the control valve is stuck in circle steer, the wheels are at full lock crab, and one cylinder is hooked up backwards. Or other-way-round on all that. So when you turn, it's running one into lock because it's already there, and when you go the other way, it's running the other into lock because it's already there.

IIRC, they had at least a couple models where there was no "true" rear steer control, there was front-only, 4 wheel crab, and 4 wheel circle, and if you cranked to lock and switched between circle and crab, you were then stuck there, at least until you switched back and straightened everything up. If you got really froggy you could go to part lock, switch modes, and make a real mess to where center on one end never happened in-time with center on the other.

I think the suggestion someone had about pull the lines from one cylinder and get a bucket, sounds like a good idea, but you'll need an extra somebody watching (or steering) and to see which line fluid comes out of. Personally, I'd swap lines on one cylinder, either at the valve or cylinder (depending on where's easier) and see what happens.

 

[JD Mark]

Breaking development!

I started tracing the lines from the cylinders and followed the small lines off the tee on the rear cylinder that I referenced above and found this on above the back of the engine bay.

I tried to see the handbook but realized I don't have one so I just fucked with it. And with it turned 90 degrees so the handle is vertical, I my front steering is now working, but still nothing out of the rear.

I'm assuming the normal position should be the way it is in the pic and I don't yet understand how it works or what the procedure is supposed to be, but it sure would have been nice to know about it last night when we were unloading. Both of the lines off those tees run up to this valve, so I assume when I turn it, it serves as bypass to the rear steer cylinder. So the procedure must be: open valve, center front wheels, close valve and put it in to 2 wheel steer mode.

So why would bypassing the rear cylinder suddenly make the front one start working? Does this add to Dethmachinefab's theory that the front and rear are fighting each other somehow?


I ordered a service manual from some sketchy site from India that was supposed to give me an instant download, but I didn't get the link. So now I'm giving them a couple hours to respond to my e-mail before I accept I got ripped off and try another sketchy site.

That's the lever that I had in my 212, except it was inside the cab.

Really stupid to put it in back...because if you're the slightest bit OCD (I am) and you don't get them straight, you will have to jump in and out while screwing with it.

But yes, this was what was used for 2WS, 4WS or crabsteer.

 

[bgaidan]

This is the one I have used in the past. They were quick

JCB Manuals PDF | Heavy Equipment Manuals

Explore the comprehensive JCB 930-4 LE Rough Terrain Forklift Parts Manual. Easily locate and order necessary parts with detailed diagrams and part numbers. Includes jcb service manual pdf.

www.heavy-equipmentmanual.com

I saw that one....it's about as questionable as the one I ordered from. Good to know they actually deliver.
They don't have the version that I ordered...or tried to.

My s/n is 1048963

They have one that's "from 500001", which is technically before mine, but the one I found was from s/n 745001 and onward so it should be a good bit newer and closer to my year. I don't suspect there's a whole lot of difference, but there is an older body style of the 520 and I don't know when they started making mine.

 

[bgaidan]

I don't know JCB specifically, but I'm guessing that the control valve is stuck in circle steer, the wheels are at full lock crab, and one cylinder is hooked up backwards. Or other-way-round on all that. So when you turn, it's running one into lock because it's already there, and when you go the other way, it's running the other into lock because it's already there.

IIRC, they had at least a couple models where there was no "true" rear steer control, there was front-only, 4 wheel crab, and 4 wheel circle, and if you cranked to lock and switched between circle and crab, you were then stuck there.

I think the suggestion someone had about pull the lines from one cylinder and get a bucket, sounds like a good idea, but you'll need an extra somebody watching (or steering) and to see which line fluid comes out of. Personally, I'd swap lines on one cylinder, either at the valve or cylinder (depending on where's easier) and see what happens.

Interesting. I'm still looking for this control valve and/or switch. I'm sure I'll find it as soon as they wake up in India and send me my manual.


So the mechanic did allegedly rebuild the steer cylinders, so it's very possible that he swapped a hose when he put them back together. I need to sit here and contemplate if it's the front or rear that's wrong.....

 

[bgaidan]

I saw that one....it's about as questionable as the one I ordered from. Good to know they actually deliver.
They don't have the version that I ordered...or tried to.

My s/n is 1048963

They have one that's "from 500001", which is technically before mine, but the one I found was from s/n 745001 and onward so it should be a good bit newer and closer to my year. I don't suspect there's a whole lot of difference, but there is an older body style of the 520 and I don't know when they started making mine.

If someone were really anal and drove this machine a lot, it wouldn't be all the hard to swap that valve out for one with an electric solenoid.

Although that's pretty far down my list of projects for this thing at the moment.

 

[Bacho]

Interesting. I'm still looking for this control valve and/or switch. I'm sure I'll find it as soon as they wake up in India and send me my manual.


So the mechanic did allegedly rebuild the steer cylinders, so it's very possible that he swapped a hose when he put them back together. I need to sit here and contemplate if it's the front or rear that's wrong.....

From my understanding of what’s being presented, it doesn’t matter if you change the front or the rear, as long as one of them changes

 

[bgaidan]

From my understanding of what’s being presented, it doesn’t matter if you change the front or the rear, as long as one of them changes

I would think one way would make the steering reversed. But I could also just just go pick on and if it's wrong, do it right and still be done faster than sitting here thinking about it.

 

[ScottRS]

So the mechanic did allegedly rebuild the steer cylinders, so it's very possible that he swapped a hose when he put them back together. I need to sit here and contemplate if it's the front or rear that's wrong.....

In my mind, you put the machine in "forward" and start moving. If you turn the wheel to the right, the front (as defined by the direction of travel) of the machine should go to the right. Whichever axle goes the correct way to make that happen, is correct, if the other goes the other way, it's wrong. You'll need to have the steering at least moving, first. But that rear steer bypass valve should at least have something freed up to move a bit.

If there's genuinely no steering mode select, the bypass valve you found in the engine bay is likely for service only and isn't supposed to be used normally, it's just used to get everything back "in-time", and the only mode you likely have, should be circle steer. If that's the case, I'd absolutely be fabricobbling a log splitter style valve into there to have independent rear steer control, or adding a solenoid valve pack to give me front-only, circle, crab, and rear-only selections off of the wheel. That is, assuming I'm doing "for me" not "for resale/flip".

 

[ScottRS]

I would think one way would make the steering reversed. But I could also just just go pick on and if it's wrong, do it right and still be done faster than sitting here thinking about it.

This. Ten minutes and a little mess and you have a machine that (maybe) steers right, or (maybe) steers backwards. Either way, win. If it steers backwards, ten more minutes and two more little messes, and it probably steers right.

 

[srf]

Guy says right but the video caption says he meant to say left

 

[bgaidan]

In my mind, you put the machine in "forward" and start moving. If you turn the wheel to the right, the front of the machine should go to the right. Whichever axle goes the correct way to make that happen, is correct, if the other goes the other way, it's wrong. You'll need to have the steering at least moving, first. But that rear steer bypass valve should at least have something freed up to move a bit.

If there's genuinely no steering mode select, the bypass valve you found in the engine bay is likely for service only and isn't supposed to be used normally, it's just used to get everything back "in-time", and the only mode you likely have, should be circle steer. If that's the case, I'd absolutely be fabricobbling a log splitter style valve into there to have independent rear steer control, or adding a solenoid valve pack to give me front-only, circle, crab, and rear-only selections off of the wheel. That is, assuming I'm doing "for me" not "for resale/flip".

Hmmm...my though was that we don't technically know what steering mode it was in, but your point that the steering mode may not be selectable at all makes sense....meaning it's just full time 4 wheel steer.

 

[bgaidan]

Guy says right but the video caption says he meant to say left

Awesome. Don't know why that didn't pop in in my searches. Off to try that now....



Edit:

Fucking hell. You win the thread.

I have 4 wheel steering that actually works.

Oh man, it would have been really nice to have found that video before the unloading shitshow last night.


Now I just need to address a few leaks and I'll be in business.

 

[srf]

Bitchin

PITA, but at least it was a cheap fix

 

[WTF?]

… the unloading shitshow last night.

 

[bgaidan]

I thought about putting my go pro out there to record the show but I had other shit to do before I could worry about that. It really was a spectacular mess of questionable decisions.

 

[bgaidan]

I got my manual. Of course it goes up to '04 and mine's an '05, but I don't see anything that's obviously different. I did actually learn that based off the VIN, mine is, in fact, a 520-50, not just a 520 like I thought. Otherwise, the manual isn't as detailed as I had hoped. But there are decent electrical and hydraulic diagrams so it should be able to answer most of my questions on those systems.

 

[Gbkeith]

Thank the .gov for making cranes expensive.

Fuckin A

 

[aczlan]

Fucking hell. You win the thread.
I have 4 wheel steering that actually works.

Oh man, it would have been really nice to have found that video before the unloading shitshow last night.
Now I just need to address a few leaks and I'll be in business.

Any chance the other one has the same issue and you could fix it and flip it for enough profit to pay for this one?

Aaron Z

 

[bgaidan]

Any chance the other one has the same issue and you could fix it and flip it for enough profit to pay for this one?

Aaron Z

Not sure I want to push my luck

 

[BillyBronco]

That is a quitters attitude.

Glad you got it fixed but I was hoping for a longer troubleshooting cat and mouse game.

 

[WTF?]

It really was a spectacular mess of questionable decisions.

Well that’s not satisfactory…
Can we get some highlights of the sketch factors? How many times were you 90% confident it was going to end up barrel rolling off the side of the lowboy? How close did you or the driver come to losing digits/limbs and how many times? Did you destroy the tilt deck trying to use it as a loading dock/ramp? So many unanswered questions…