‘84 JCB 1550B Backhoe

[Tim Bradham]

Hello, new to this forum! I’ve recently pick up a ‘84 JCB 1550B 2wd backhoe, it’s been working great on all the hydraulics, until yesterday when the rear bucket was working fast in both directions, but the movement reaching out seems to slow way down. It feels like under the lever, going into the switch valve, seems like it doesn’t set to zero. Not sure if I’m saying that correctly, very new to this machine, but I’m learning a lot owning it. Also the right side landing cylinder goes up fast, but really slow going down. Thanks for any advice in this issue. Thanks Tim

 

[GEOD998]

For starters-is your hydraulic fluid at the correct level when the machine is in the proper position for checking it? if the rubber accordians are carefully removed from the control cover, you can watch the linkage movement. If you are trying to watch the linkage travel,keep in mind, you shouldnt have to force anything to get full travel up or down. I've had linkage rod come loose and get out of adjustment on several machines on was on my case1450 modulator linkages and it can make you think the trannys died.. I cant remember which of my other machines linkage issues made me pucker, but, I'd start with that easy stuff and let us know. Maybe some of the more learned guys will chime in...I just try to keep them running and still have enuff money left for food-lol

 

[Tim Bradham]

For starters-is your hydraulic fluid at the correct level when the machine is in the proper position for checking it? if the rubber accordians are carefully removed from the control cover, you can watch the linkage movement. If you are trying to watch the linkage travel,keep in mind, you shouldnt have to force anything to get full travel up or down. I've had linkage rod come loose and get out of adjustment on several machines on was on my case1450 modulator linkages and it can make you think the trannys died.. I cant remember which of my other machines linkage issues made me pucker, but, I'd start with that easy stuff and let us know. Maybe some of the more learned guys will chime in...I just try to keep them running and still have enuff money left for food-lol

Thanks for replying! I'll get back out to the property this weekend and see if I can go over things, and let ya'll know.

 

[casey518]

How are the loader functions? Any problems there?

 

[Tim Bradham]

How are the loader functions? Any problems there?

The loader with clam shell is working fine. I’ve noticed under the right of the seat, where all the hoses meet, makes a groaning noise. I’ve double checked the hydraulic fluid with all the cylinders, closed, and it’s full. Where the lever control is to control the rear landing gear, it still seems it doesn’t have a neutral from open and closing. Was wondering if I took that lever apart, where the plunger is, if it has seals for open and close.

 

[Delmer]

Well, you've said some things about the control valve that are kind of fuzzy for me to understand, so bare with me.

It sounds like one function isn't operating the same as it did, or the same as you expect it to, right? and that one function is only operating different in one direction? You really need to see if that function operates the spool up and down the same distance as the other spools.

Look at some manual hydraulic valves online, they usually have a cap on the end of each section on the other end from the control handle. That cap looks important, but it's just there to hold a spring and keep dust out. You can remove that and the worst that will happen is parts fall out if it's broken, it should be obvious how it operates by looking at it, the spring compresses against the valve block when the spool is moved one direction, and compresses against the cap if the spool is moved the other direction. If too much oil gets in there, then it won't move because the oil locks it, not enough room. There is an o ring, or seal under the spring usually to keep oil from leaking out. The seals for open and close are metal on metal, nothing to repair.

 

[Tim Bradham]

Well, you've said some things about the control valve that are kind of fuzzy for me to understand, so bare with me.

It sounds like one function isn't operating the same as it did, or the same as you expect it to, right? and that one function is only operating different in one direction? You really need to see if that function operates the spool up and down the same distance as the other spools.

Look at some manual hydraulic valves online, they usually have a cap on the end of each section on the other end from the control handle. That cap looks important, but it's just there to hold a spring and keep dust out. You can remove that and the worst that will happen is parts fall out if it's broken, it should be obvious how it operates by looking at it, the spring compresses against the valve block when the spool is moved one direction, and compresses against the cap if the spool is moved the other direction. If too much oil gets in there, then it won't move because the oil locks it, not enough room. There is an o ring, or seal under the spring usually to keep oil from leaking out. The seals for open and close are metal on metal, nothing to repair.

Sorry kinda new to this! But this is what I was referring to. From the left, 3rd and the last one seem to just freely move up and down, with no resistance. The last one, the bucket comes quickly, but slowly out. And the 3rd one, as of yesterday, want even try to put the landing down. Thanks for your input.

 

[Tinkerer]

You posted that you are having problems with the rear bucket. You posted image is the loader valve ?
This isn't your valve. It is from the next generation of 1500B's.
But, it will give you an idea of what you are dealing with.


This is the backhoe valve. As I said yours may not be exactly like this one.

 

[Tim Bradham]

You posted that you are having problems with the rear bucket. You posted image is the loader valve ?
This isn't your valve. It is from the next generation of 1500B's.
But, it will give you an idea of what you are dealing with.
View attachment 259997
View attachment 259998
This is the backhoe valve. As I said yours may not be exactly like this one.
View attachment 259999

Thank you, Guess I'm going to have to just tear it apart, and see what's going on. I've ordered a parts book, that will give me more description and numbers for this model. Thanks again

 

[Delmer]

Tim, in your picture I only see two valves, how many control levers operate that valve block? And I think I see a torch cut hole in the upper right, which means some numbskull has had his mitts on the plumbing, what's going on with that?

Tinkerer's diagram shows three valves. I would have expected yours to all resemble the one on the left of the three with the shortest cap. But maybe yours are like the middle valve with the longer cap? looks like those caps unscrew, but it should be clear when you clean one up. The springs inside the cap provide the centering action which is what it sounds like you're talking about. Oil filling the cap will prevent the spool from going down far enough to activate the down stroke all the way. You'll see this by comparing the spool travel to the other spools.

 

[Tim Bradham]

Tim, in your picture I only see two valves, how many control levers operate that valve block? And I think I see a torch cut hole in the upper right, which means some numbskull has had his mitts on the plumbing, what's going on with that?

Tinkerer's diagram shows three valves. I would have expected yours to all resemble the one on the left of the three with the shortest cap. But maybe yours are like the middle valve with the longer cap? looks like those caps unscrew, but it should be clear when you clean one up. The springs inside the cap provide the centering action which is what it sounds like you're talking about. Oil filling the cap will prevent the spool from going down far enough to activate the down stroke all the way. You'll see this by comparing the spool travel to the other spools.

Thanks for helping. It has 6 controls and valves. That spring action for centering the valve is what it seems it’s lost. I’ll have to disassemble it and see what’s going on inside. Sticking, dirty or something in not allowing the landing gear to go down, and the bucket to go slow outward. I’ll keep y’all updated on progress. Another one that someone neglected and I’m trying to make it right.

 

[Delmer]

... not allowing the landing gear to go down, and the bucket to go slow outward...

I'd expect both of those directions of those functions to push the spool down, which would allow leaking oil do prevent the movement. You can confirm that those functions operate that direction by pushing the spool down, and that those spools do, or do not, move the same distance. You should be able to remove the covers without removing the valve body, or removing any hydraulic hoses.

 

[Tinkerer]

What is the serial number of your machine, Tim ?
I don't know if it is legal, but there are vendors on eBay selling access to JCB's Parts Pro Catalog.
For those that don't know, that catalog covers everything JCB has made.

 

[Tim Bradham]

What is the serial number of your machine, Tim ?
I don't know if it is legal, but there are vendors on eBay selling access to JCB's Parts Pro Catalog.
For those that don't know, that catalog covers everything JCB has made.

 

[Tinkerer]

I think you need a service manual if you are going to do any repairs to your JCB. It will save you countless hours whenever you need to work on it.
It appears you need, JCB 1550b Service Repair Manual 9803/3250. I may be wrong.
They are readily available from many vendors on the internet in the printed version or .pdf version.
Prices vary dramatical !
JCB EXCAVATOR SERVICE SHOP MANUAL Tractor Backhoe Loader GUIDE 9803/3250 3CX 4CX 780537999250 | eBay

 

[Tim Bradham]

Thanks for y’all’s advice, and input. I took the spool apart on the rear bucket, and the lower retainer that holds the spring up, was shot! Nobody had one, and it being Memorial Day, I ran to my shop, and made one on my lathe. I cleaned everything, got it back together, and it’s working great, both directions. I’ll get the other 5 cleaned, and checked out as well, through out this week.

 

[Tinkerer]

Quite amazing how those are failing.
You are very fortunate to have a lathe and the skills to use it.
A lathe is something I never seemed to have the spare money to buy. I should have bought it anyway.