Loader ford loader spool valve

[berky]

I have a 4500 TLB and have a problem with the front loader spool valve. If I have dumped a load and want to back spread it, the bucket wants to curl back up once preasure is applied from the dumped material. Not sure if there is some check valve not holding, the spool is worn out, or just what the issue may be. The cylinders have recently been rebuilt so I know internal leakage is not the problem. Anyone have any ideas on where to begin looking or any diagrams on the 4500 loader valve that they could share?

 

[LD1]

The cylinders wouldnt have been the problem anyway.

Does the bucket drift open (dump) when you have a load in it? Do you have the self-leveling valve.

It "should" be the 740 series loader on that tractor IIRC. Try here New Holland (74-SERIES) - FORD LOADER (1/75-7/8) Parts Diagrams

 

[berky]

The cylinders wouldnt have been the problem anyway.

Does the bucket drift open (dump) when you have a load in it? Do you have the self-leveling valve.

It "should" be the 740 series loader on that tractor IIRC. Try here New Holland (74-SERIES) - FORD LOADER (1/75-7/8) Parts Diagrams

LD1 Thanks for the response. Does not drift open when loaded. No self leveling valve.
The diagram does not show the internals or a couple of other plugs that mine has or their purpose.

 

[LD1]

Try this:

After you dump whatever is in the bucket, dump it ALL the way. Hold the lever there for a few seconds. Then curl back to wherever you want it for backdragging. See if the loader holds it position then.

I suspect the issue is that valve lacks a regen feature. Which pressurizes both work ports. So when dumping something and wanting to backdrag it to feather it out.....the weight in the bucket and gravity cause it to dump faster than the cylinder can fill with fluid. Thus sucking in air and causing a "floppy" bucket.

By dumping all the way, THEN holding the lever there for a few seconds at full dump, forces the air out. curling back to wherever you want it is hydrauics pumping AGAINST gravity and not WITH it. So no air will be sucked it, and bucket should hold firm.

 

[berky]

Try this:

After you dump whatever is in the bucket, dump it ALL the way. Hold the lever there for a few seconds. Then curl back to wherever you want it for backdragging. See if the loader holds it position then.

I suspect the issue is that valve lacks a regen feature. Which pressurizes both work ports. So when dumping something and wanting to backdrag it to feather it out.....the weight in the bucket and gravity cause it to dump faster than the cylinder can fill with fluid. Thus sucking in air and causing a "floppy" bucket.

By dumping all the way, THEN holding the lever there for a few seconds at full dump, forces the air out. curling back to wherever you want it is hydrauics pumping AGAINST gravity and not WITH it. So no air will be sucked it, and bucket should hold firm.

I have already been doing that, but it takes 5-7 seconds before the cylinder pressures up. and then you have to do it everytime. The tractor use to be just barely doing this but seems to be getting worse. I am looking for ideas on how to fix it, since it has to be something internal to the spool valve.
thanks

 

[LD1]

So you are saying that doing that corrects the issue?

And taking 5-7 seconds to purge out air is alot of air being sucked in.

In this case, I'd suspect the cylinder over the valve. But a sure fix is to replace the valve with one that has regen