JCB 801 track Problem

[muchmud]

thanks to the info received through this forum my old 801 is all singing and dancing now, except it now seems to want to dance quicker on one track than the other, another mystery job then... .

[Stock]

what the track tension like?

[muchmud]

what the track tension like?

To the MK1 eyeball it all looks the same so i have run a measure over both tracks height length and they match to within millimeters, having said that it has had a one track replacement just before i got it but as said it all looks matching. During various other work i've carried out on it with cab off, seat battery and holder floor plates all removed i noticed that the left hand track control lever is directly connected to a valve block situated just about under the left foot position while the other lever has a "rigid" cable connection going back under the seat area. I'm starting to wonder if its worth opening it all up again to see if theres adjustment there .

[Muz]

To the MK1 eyeball it all looks the same so i have run a measure over both tracks height length and they match to within millimeters, having said that it has had a one track replacement just before i got it but as said it all looks matching. During various other work i've carried out on it with cab off, seat battery and holder floor plates all removed i noticed that the left hand track control lever is directly connected to a valve block situated just about under the left foot position while the other lever has a "rigid" cable connection going back under the seat area. I'm starting to wonder if its worth opening it all up again to see if theres adjustment there .

Ive moved these posts to its own thread, as it was a different topic to the op's



Sounds like a plan Mud .... lookout too for a build up of dirt around any yokes or pivots .. sometimes thats all it is and restricts the travel of a lever as such .. its worth clearing out all the crap with a pressure washer, and oiling any joints you can find .. although if one is cable operated and the other a solid linkage, theres bound to be a difference there, as the cable may have 'stretched' .. hard to fathom why a manufacturer would build such a design though .. but I suppose we are talking JCB here

[Dan]

i noticed that the left hand track control lever is directly connected to a valve block situated just about under the left foot position while the other lever has a "rigid" cable connection going back under the seat area.

kidding right ? ..... are you sure one isnt for the dozer lever or aux service ... surely theyd never have two different types of connection for tracks ?

[muchmud]

Muz yep its a JCB alright. when i had it all apart i did do a pretty good clear out as it was full of wet mud dust and i have to say i was surprised to see the difference in the track lever connections but then who am i to question Mr. Bamfords designs. I will give the lube idea a healthy application and see what happens, if that don't work then guess i'll try grab a spare track motor and swap them which will either be the answer or the begining of an elimination process..



Dan mate its definately how its connected, the valve block in question works the Boom slew and the left hand track, there's a smaller block under the right foot position but its a Breaker (not fitted) control . Definately the right hand track is cable linked to somewhere under the rear of the seating position and it may be adjustable so i gotta look. It has a blade hand control lever to my right but thats on its own valve block so thats what i got.

[Muz]

if that don't work then guess i'll try grab a spare track motor and swap them which will either be the answer or the begining of an elimination process..

Have a look and see if the travel on the valve block spools look the same for each motor ? the cable will definately be adjustable, it will have a shroud/sleeve held in a clamp at each or one end, that will have a couple of nuts on the shroud allowing you to shorten or lengthen it, the thing is... its a bi directional control, so essentially what you need to do is centre it properly .

If you think its ok and the fault is else where, before getting a spare motor reverse the pipes to the other side and see if the fault is replicated on the other motor, and it starts tracking off line in the other direction instead

Now hold myself up

Before I go any further ... Is this the problem ? .. it wont track in a straight line ?

[muchmud]

Have a look and see if the travel on the valve block spools look the same for each motor ? the cable will definately be adjustable, it will have a shroud/sleeve held in a clamp at each or one end, that will have a couple of nuts on the shroud allowing you to shorten or lengthen it, the thing is... its a bi directional control, so essentially what you need to do is centre it properly .

If you think its ok and the fault is else where, before getting a spare motor reverse the pipes to the other side and see if the fault is replicated on the other motor, and it starts tracking off line in the other direction instead

Now hold myself up

Before I go any further ... Is this the problem ? .. it wont track in a straight line ?

Yep thats it alright, its a "slow" difference when tracking any distance but when using the blade its more of a problem, sometimes it won't push at all if there's any turning required and again i've tried to turn when climbing a small bank which resulted in having to back off and re-aim so i haven't got to do the turn, its best described as tho its got less power than the other track like it can almost keep up until it comes under load but it seems fine in reverse !

[Muz]

Yep thats it alright, its a "slow" difference when tracking any distance but when using the blade its more of a problem, sometimes it won't push at all if there's any turning required and again i've tried to turn when climbing a small bank which resulted in having to back off and re-aim so i haven't got to do the turn, its best described as tho its got less power than the other track like it can almost keep up until it comes under load but it seems fine in reverse !

Aye .. sounds like our old friend the orbital valve .. or rotary distributer .... its the yoke that allows oil to the track motors and dozer blade when the machine is rotated in any direction. When you mentioned using the dozer blade, that would indicate a seal failure within the unit, if you change over the feed pipes to the track motors and the problem is still the same, the valve will most likely be the cause.

That said .. IIRC that machine has a triple section gear pump doesent it ? .... It could also be, that one of the pump sections is down in pressure, but you would see that elsewhere, because the guilty section powers a track motor and another service .. the dipper ram I think .. so you would need to do a pressure test on each bank to find this out.

Said pile of Junk ... doh sorry .. JCB has no test points IIRC so you need to crack a high pressure line on the pump output and insert a test gauge, then pull on a service at full revs till the main relief blows and see what you get ?

If it were me I'd try testing the pump first

[muchmud]

Holy s..t BUT i'll give it a go .

[Muz]

Well its the old story .. a set of guages can save you a whole load of heartache ......... and Ive layed under enough diggers in my time to prove that

Its hard to know if another service is not working right if its the only digger you have, of that size and you are used to it .. only the guages will show the fault .. mind you if it 'is' the dipper and your machine wont blast a 12" bucket through hard/firm ground then its a fair likelihood it is below par ?

Usually the 3 sections of that pump would be split something like this .....Aux/dozer/slew....... Left track/dipper/bucket...... right track/boom lift/boom offset.......

The order may vary but the principle is the same, so if one of the banks is down, so will the other service be, that it powers.

Bring on the advantage of a variable displacement pump

[muchmud]

Well its the old story .. a set of guages can save you a whole load of heartache ......... and Ive layed under enough diggers in my time to prove that

Its hard to know if another service is not working right if its the only digger you have, of that size and you are used to it .. only the guages will show the fault .. mind you if it 'is' the dipper and your machine wont blast a 12" bucket through hard/firm ground then its a fair likelihood it is below par ?

Usually the 3 sections of that pump would be split something like this .....Aux/dozer/slew....... Left track/dipper/bucket...... right track/boom lift/boom offset.......

The order may vary but the principle is the same, so if one of the banks is down, so will the other service be, that it powers.

Bring on the advantage of a variable displacement pump

.
hotel echo lima papa foxtrot oscar romeo papa indigo tango yankee seirra seirra alpha kilo seirra, i wuz just a lorry driver in real life.

[Muz]

. hotel echo lima papa foxtrot oscar romeo papa indigo tango yankee seirra seirra alpha kilo seirra, i wuz just a lorry driver in real life.

2 Sierras too many and missing an echo

[MadMike]

Why does no one evr come back and finish some great old threads ? so much unfinished business

[2414.ginger]

Yeah Mike I know, the number of times you find something interesting to read, you get to the last page and WTF, why do these people never come back and finish the job.

Mind you I think if you checked on all my threads I am probably just as guilty as the next man, although that said some of my problem threads are still ongoing, and have yet to reach a conclusion. Note to self, get them finished off.

Actually on a different theme I have just found out you don't drag and drop the the little imoges (if that is what they are called) you just click on them and they magically appear at the point you have typed too. So a result for me.