I have a problem with a JCB loadall from 1985. It has a torque converter and a Borg Warner shuttle transmission. The loader starts driving when I put the lever control in forward or reverse position, without using the throttle! I bought this loader second hand, so I do not know if this is normal. Should the loader not start driving when I use the throttle? If Yes, what can be the problem? Torque converter or perhaps the shuttle valve?
JCB 520M torque converter or transmission problem
- Thread starter Giel
- Start date
Timbo
Member
- Location
- Gods County
Yes it will creep when put into gear but brakes should easily hold it still . what speed is your idle set at ??
- Location
- Oxon
Engine idle about 800rpm.
And fix the brakes. It's normal for it to gently creep forward at idle on flat ground.
Especially if your in a lower gear.
If its creeping forward in neutral then that is a problem and will be the bevel spring on the clutch pack broken.
I bought the loader second hand and I am working with it since a few days. Unfortunately I didn't see that he tachometer isn't working. Assuming the engine will run with 800 rpm idle speed. The brakes don't stop the loader at idle speed, even not in the third gear. When I am braking I am hearing a noise coming from the brakes. Then sort of stop and go happens. After a few seconds I stop braking because the engine power is too big and I am afraid I am damaging the brakes. Do you think the brakes are worn out?
- Location
- Oxon
If you got a good brake pedal feel then yeah brakes will be worn out. Brake chattering noise is normally due to lack of oil changes or wrong spec oil.
Brakes are easy enough to sort on them old jcb axles in think.
Thank you very much for your fast reply. I will fix the tachometer and check the brakes. If it is only a problem with the brakes I am already happy.
diggerjones
Member
- Location
- South cheshire, audlem
I wouldn't worry about the tachometer. Just adjust the throttle cable till the engine is on the lowest tick over you can achieve
- Location
- Oxon
yes its in the front axle.
davidroberts30
Member
- Location
- pembrokeshire
Lift the throttle up!!and clean around it
Ok, it seems to be relatively easy job, I mean disassembling the brakes. In the service and part manual I can't really see if it is a closed system. But they are writing about a JCB Light hydraulic oil and bleeding procedure. So, it has to be closed. That's nice, I don't have to drain the oil of the axle.
- Location
- Oxon
The discs run in the axle oil. You will need to change that oil
The light hydraulic oil is in the brake pedal circuit.
Just follow the brake pipe to front axle. It goes in a plate. Drain axle, remove brake pipe and remove the plate. Theres a brake piston in there you will need to reseal then the brake discs.
Do not put hydraulic oil in the axle go buy the proper oil spec for the axles. I think you need about 45 litres of it
Light or thin Hydraulic oil goes in the brake pot in the cab. Something like a 10w hydraulic oil I think or get the manitou LHM mineral brake fluid coloured green. Do not use DOT 4 type brake fluids in it.
- Location
- Oxon
Front axle and brakes will be the same as the rear axle of an old JCB 3cx digger from the late 80s to mid 90s
There one other thing that I didn't mention concerning this issue. The leader has a dump control. But pressing the dump control pedal has no effect. The cable is ok and it pushes the shuttle valve pin or spool back into the reverse. I don't know if it goes far enough inside. And that's the reason why I came to the idea that this problem (loader doesn't stop during braking) has something to do with the transmission.
- Location
- Oxon
The pin needs to be out for it to drive. Pushing it in stops the drive but it's a useless system that doesn't work very well. It's really only used to change gear on the move say from 3rd to 4th while on road.
Your brakes should be good enough to hold machine in 2nd gear almost flat out engine rpm! If transmission is good you would struggle to do this in 1st and that's a good thing.
Torque converters are designed to stall out under a certain load and rpm. Trying to disconnect drive or reconnect drive with foot on brakes just doesn't work well on most torque converter handers.
The idea was for inching up to stuff but in practice it's just uncontrollable and juddery plus harsh on the transmission clutches and drive line.
Just FIX the brakes. It dont matter what transmission is doing the brake still need to work.
I think your confusing the driving of machine with a hydrostatic system. A torque converter system is nothing like a hydrostatic drive system.
Your last sentence I probably misunderstand. Please have mercy on me, it is not my mother language 
Do you mean:
A torque converter system is not like a hydrostatic drive system.
OR: A torque converter system is nothing ELSE like a hydrostatic drive system.
One point is interesting. I tried to stop the loader in the 1st gear with the brakes. I have to struggle to do this and it is not succesfull. Until know I not tried to stop it in the 2nd or 3rd gear. I will do this weekend an come back to you with the results.
I agree with you, the brakes should be OK always. But perhaps they don't have a problem. I will make a few brake tests at higher speed.
Thanks for the good information and have a nice weekend!
Do you mean:
A torque converter system is not like a hydrostatic drive system.
OR: A torque converter system is nothing ELSE like a hydrostatic drive system.
One point is interesting. I tried to stop the loader in the 1st gear with the brakes. I have to struggle to do this and it is not succesfull. Until know I not tried to stop it in the 2nd or 3rd gear. I will do this weekend an come back to you with the results.
I agree with you, the brakes should be OK always. But perhaps they don't have a problem. I will make a few brake tests at higher speed.
Thanks for the good information and have a nice weekend!
- Location
- Oxon
Your last sentence I probably misunderstand. Please have mercy on me, it is not my mother language
Do you mean:
A torque converter system is not like a hydrostatic drive system.
OR: A torque converter system is nothing ELSE like a hydrostatic drive system.
One point is interesting. I tried to stop the loader in the 1st gear with the brakes. I have to struggle to do this and it is not succesfull. Until know I not tried to stop it in the 2nd or 3rd gear. I will do this weekend an come back to you with the results.
I agree with you, the brakes should be OK always. But perhaps they don't have a problem. I will make a few brake tests at higher speed.
Thanks for the good information and have a nice weekend!
"A torque converter system is not like a hydrostatic drive system."
They both drive very differently.
You should easy hold machine back on the brakes in all gears at low rpm but you will struggle to hold it in 1st with higher rpm if the transmission is in decent working order.
- Tags
- udder
The London Palladium event “BPR Seminar”
This is our next step following the London rally 
BPR is not just a farming issue, it affects ALL business, it removes incentive to invest for growth
Join us @LondonPalladium on the 16th for beginning of UK business fight back
lwtheatres.co.uk
BPR is not just a farming issue, it affects ALL business, it removes incentive to invest for growth
Join us @LondonPalladium on the 16th for beginning of UK business fight back
BPR Summit | LW Theatres
lwtheatres.co.uk