JCB 212S Brakes

[Billie]

Hi there.
Ive had this machine for about 6 months now and its come a long way since I got it. Engine was full of water when I got it, It hadnt been used in 2 years because of what they thought was the injection pump. (ended up being restriction in fuel supply) In those 2 years, water was filling up the engine by rain entering in through the dented in top of the air breather, filled up the air filter assy, and right through to the intake. Quite a mess..

Anyway, Its running now and I got the thing for a steal. Needs pins and bushing (9500 hrs) of course but I just cleared a back yard (about 20 hours total) and it seems to be holding together just fine.

My question is, the brakes on this thing are..not right. Hard to explain, but they have tons of power, as in it will lock all 4 up at full speed. But they are very uncontrollable. There's not alot in between on and off I guess. And there is a slight delay. Im pretty good with them now but Id like to get them to how they should be. Supposedly the friction plates and steels were changed not alot of hours ago (in the hopes of fixing same problem). They release fairly normal. As far as I can tell its a problem on the hydraulic side of it, not pads etc.

Also, when you press on the brakes with different foot pressure, you can feel and hear pulsating slower to faster, the more pressure is applied (Like the pump is charging something) Even at idle, engine will chug, maybe once every 5-10 seconds, as if its charging something.

I am suspect of the accumulators on the brake system, am I way off track or? I cant find anything on the internet on brake systems with accumulators really. Can they be recharged? From what I understand they are like a water pressure bladder tank, but under way higher pressure and filled with nitrogen.

Thanks, Ive absorbed one pile of info from this site!

 

[Anto Modded]

The 3cx has 15 or so washers in the back axle for brakes (dont know what there called exactly) Im guessing that 2cx would be similar but also the 97 or 00 on had servo's as i drove a 96 and when i went to a 01 the brackes felt servo assisted. Maybe check the fluid or look into the servo side of things. Machine looks 1997 - 2001.

 

[willie59]

I'm not familiar with the 212 machine. Does it have hyd brakes powered by the hyd system of the machine? Or does it have hyd boost assisted brakes powered by the hyd system with each brake having a master cylinder to apply brakes?

 

[Billie]

Thanks for the replies! Yep the machine is a 1999. It has hyd. brakes powered by the hyd. system. One brake pedal, and all 4 wheels have brakes. There is no separate fluid or anything, just the common hyd. fluid. The brake system/block is what the other 2 pics are of, crappy picture sorry. I have the service manual, but its vary vague on the braking system (other than changing steels and plates etc.) It does say that the accumulators are supposed to "charge up" so that you have up to 12 brake applications, if the backhoe stalls etc.
I know when a water plumbing pressure tank is water logged, the pump comes on and off way to often. It kind of seems like that is whats happening here, the hyd. pump is charging the brake system non stop, since it has no buffer maybe. (accumulators pooched?)

 

[willie59]

Well, it's not really acurate to compare the accumulator in a water system to that accumulator in this type of brake system. They work similar, but have one big difference, in a water system, the water is delivered out of the system to never return, the accumulator helps keep an even pressure and controls surges and such. In your braking system, hyd system fluid is delivered to brakes, but it returns back to be dumped back into the tank circuit. I'm thinking, not certain though, you have a problem with the brake control valve. When brakes aren't being used, the system brings brake system up to pressure then unloads. A back check valve keeps this fluid in the brake circuit and the accumulators are now pressurized. When you depress the brake pedal, it delivers this pressure to the brakes and the pressure is replaced by the pump as pressure drops. When you release the brake pedal, the pressure that was delivered to brakes is vented back to tank via the tank circuit. If your pump is constantly charging the brake circuit, I'm thinking that you may have a problem with either back check valve allowing brake system pressure to vent back into hyd system circuit, or problem with brake control valve allowing the brake system pressure to vent though the control valve to the tank circuit. Just a few thoughts.

 

[Billie]

Ok, well I will have to do some more investigating to try and narrow it down then. Accumulators in general, do they very often go bad? Can they be recharged (nitrogen?) or are they a replacement part? There is no test port on the actual green accumulators, so I dont even know how to check pressure or add etc. Ill have to get a guage and check hyd. pressure ports on the brake system to start.

 

[willie59]

I don't think you can charge those type of accumulators. But broken or not, I don't think the problem you describe is a problem with accumlators.

 

[lee]

hi mate ive had a bit to do with these is this description correct you put your foot on the brake there is a slight delay before anything happens then suddenley it wants to throw you out through the window and yes if you put your foot on the brake the engine pulses chargeing the accumilator but only does this accasionally when your foot is off the brake if this is so this is how they are the jcb 526 had the same system in the 90s
this brakeing system is completley different to the 214 or 3cx ect but if you need to know more google digger doctor uk he ive seen at least 4 of those machines in his yard for spares in the last 6 months and he will know about any problems you have if not post a reply i will help if i can good luck

 

[Billie]

Hi, Lee. Yes the flying through the window description fits quite well actually lol. So the way the brakes are is as good as it gets then? Doesn't seem right but at least it stops I guess.
I actually just seen a 1999 jcb 520 sell at an auction, it had pretty much the exact same axles and brake system. Sold for $13500CA with 6500 hours.
If this is how the brakes are, I'll just carry on and not worry about it. Thanks very much!

 

[lee]

hi billie just a thought change the hub oil regular on that machine or the brake contaminate the oil causeing problems in the hub

 

[superlandscapin]

same problem

i have a 1999 520 jcb loadall that does the exact thing. i also was going to change out the fluid in the hubs or maybe theyr just low. let me know if you get it figured out and i will do the same if i get mine fixed

 

[Drc]

JCB Brakes use hydraulic fluid not Dot 3, if someone put in dot 3 you've got an expensive fix of all seals

 

[Billie]

Yes that 520 I seen had the same problem too. It can't be right, by the time the brakes apply, you are into or through whatever it was you wanted to stop for. The brakes have tons of power, it will lock all 4 up no problem. Just the delay is a killer. I've changed the hub oil, used the jcb "special gear oil" I m guessing it has friction additive. These models use the systems hydraulic oil, there is no separate brake fluid reservoir. I will post if I find anything out. Its used for snow at the moment so I dont really want to tear into it.

 

[Billie]

Update on the brakes, I got them working good now. I ended up finding accumulators from England, the ones on my BH are the same (or roughly the same) as what is used on Citroen cars for their hydraulic suspension. Long story short, they were a fraction of the cost that the JCB dealer wanted here, so I thought it was worth a try. The ones I got are rated 200bar less than what my book has listed, so either I wont have as many emergency brake cycles, or they wont last long, either way, it cant be any worse than it was haha. So far they work great, no more engine chugging all the time (to charge the brake system) and the brakes stop the machine when pressed ( not 2 seconds later)

 

[djkeev]

That's great you've located the problem!
I also have a 212s 4x4x4 and it is a great machine though it is beginning to show it's age.
I only wish I had an owners manual for some of the lights on the warning panel are a bit vague to me. Words would be nice... but then again.... I'm old!

Dave

 

[Mr.JCB]

These guys have helped me out in the past and they pretty cheap. www.becequipment.ca

 

[n185tj]

Billie I'm having the same problem! but mine pukes hydro fluid all over when depressing the "brakes" i am desperate to find a fix. i have replaced the brake charge valve? ( its under the steering wheel) twice! and its now doing it again. i have the pulsing like you did also... and what is JCB druid software i would love to have a manual on the computer that i could look up the machine parts. I live in idaho and not a lot of JCB support here.
Thanks much!

 

[Tony H]

Just jumped into a 2007 JCB 520-50 at work that has the same "no brakes, then lock up" I mentioned it to the guys and they say it was always like that. It can't be right. Just recently the Low Brae Pressure light came on... Okayyyyy, what does that mean?

 

[JCB2CXFI]

Update on the brakes, I got them working good now. I ended up finding accumulators from England, the ones on my BH are the same (or roughly the same) as what is used on Citroen cars for their hydraulic suspension. Long story short, they were a fraction of the cost that the JCB dealer wanted here, so I thought it was worth a try. The ones I got are rated 200bar less than what my book has listed, so either I wont have as many emergency brake cycles, or they wont last long, either way, it cant be any worse than it was haha. So far they work great, no more engine chugging all the time (to charge the brake system) and the brakes stop the machine when pressed ( not 2 seconds later)

Hi Billie,
I found your old solved problem, and I have same prob in my Jcb.
Did you have any problems with Citroen accumulators?
Could you remember what was type number or car type (Citroen BX, CX?)
Originals are too expensive =)
Thanks!
Pat

 

[jcb jeff]

Hi
Do you have a serial no of machine?
These are power brakes with a charge valve which charges brake accumulators which store brake pressure .
The oil for this system is shared by the man hyd oil.
Is you machine sound like it is constantly charging the circuit which means you will hear engine note change on tick over.
The brake discs are located in the 4 hubs you will see a pipe going to each hub.
As said already the hub oils need to be kept clean as only a small amount of oil present.
This oil needs to be a wet brake axle oil or if genuine it will be JCB special gear oil plus in the hubs.