What causes this?

[handirifle]

On several pieces of equipment, I own or have rented, or borrowed, I see it on every one, when using the FEL the bucket will go so far, then you need to sort of "cycle" the control to keep it going.

In other words, the bucket will drop, say 70% of the way, then you need to return the control to neutral, rev, and do it again tl get the rest of the travel. What causes this? Is it wear, or normal for some reason I cannot figure?

 

[beenthere]

Are you familiar with the dump feature that causes this?
Do a search on regenerative circuit, I believe, to get an explanation.

It is a feature to get a faster dump when the bucket has a load. For some, takes some getting used to, but is a benefit.
For example
http://www.tractorbynet.com/forums/hydraulics/169883-can-someone-explain-regen-etc.html

 

[SPYDERLK]

Iv never seen anything like that, neither in regen or regular mode. Perhaps I misinterpret the description.
larry

 

[handirifle]

WOW! Beenthere
Went there. Read the thread. Boy this passes over my head pretty quick. I got a general idea on what they're talking about, that does help.

My main concern was something was wrong woth them, but I see what they are doing.

Thanks

 

[dcyrilc]

On several pieces of equipment, I own or have rented, or borrowed, I see it on every one, when using the FEL the bucket will go so far, then you need to sort of "cycle" the control to keep it going.

In other words, the bucket will drop, say 70% of the way, then you need to return the control to neutral, rev, and do it again tl get the rest of the travel. What causes this? Is it wear, or normal for some reason I cannot figure?

Mine does the same thing, but will actually begin curling if you don't rev up the RPMs. In my case, I associate it with an old tired machine with highly worn valves.

 

[handirifle]

Mine does the same thing, but will actually begin curling if you don't rev up the RPMs. In my case, I associate it with an old tired machine with highly worn valves.

That's what I wondered, but given what they say and that every machine I've used has done it, I'm hoping it's be design.

 

[dcyrilc]

That's what I wondered, but given what they say and that every machine I've used has done it, I'm hoping it's be design.

I've used construction equipment for years (backhoes and loaders). They don't do it. I'm assuming wear, but time will tell after I rebuild or replace my valves this winter.

It's frustrating to have the lever at full dump and have the bucket curling.

 

[sweettractors]

I've used construction equipment for years (backhoes and loaders). They don't do it. I'm assuming wear, but time will tell after I rebuild or replace my valves this winter.

It's frustrating to have the lever at full dump and have the bucket curling.

I have never came up on this situation either, I would think wear in cylinders, pump, valve, etc. Ken Sweet

 

[J_J]

Maybe the lever for that valve is not coming back all the way to neutral. Could be weak spring. Leaking spool in that valve could cause that.

 

[MD3]

Are you talking about the bucket tilt cylinders? If so after the load is dumped it will take a moment for the hydraulics to catch up to the cylinders.

 

[AKKAMAAN]

This is a common design error...what happens is that gravity from the bucket pushes oil out of one side of the cylinder piston, faster than the pump can replace the void on the opposite side of piston.....
depending on how cylinder is hooked up, extending or retracting, wqhen this happens....problem can be solved in differnt ways.....
a regenerative valve is best cure if cylinder is extending....but do not work on retract...
one way adjustable orifice/ check valves (on meter out)is another option, that will slow drainage so pump can keep up with the void....


Question: IS CYLINDER EXTENDING OR RETRACTING WHEN THIS BUCKET DROPS DOWN??

 

[SPYDERLK]

Oh. Just voids in the cyls. Didnt realize he was describing that phenomenon.
larry

 

[dcyrilc]

This is a common design error...what happens is that gravity from the bucket pushes oil out of one side of the cylinder piston, faster than the pump can replace the void on the opposite side of piston.....
depending on how cylinder is hooked up, extending or retracting, wqhen this happens....problem can be solved in differnt ways.....
a regenerative valve is best cure if cylinder is extending....but do not work on retract...
one way adjustable orifice/ check valves (on meter out)is another option, that will slow drainage so pump can keep up with the void....


Question: IS CYLINDER EXTENDING OR RETRACTING WHEN THIS BUCKET DROPS DOWN??

Extending for mine. Not sure about the OP. Mine will also do it with an empty bucket.

 

[AKKAMAAN]

Extending for mine. Not sure about the OP. Mine will also do it with an empty bucket.

Extending means you could utilze a SUN Hydraulics regenerative valve between control valve and cylinder...around 100-150$...
another option is to use a one way adjustable restrictor/flow control valve, on the rod side line..... around 30$

Read this pdf from SUN about regen valve tips....
To design a regen valve installation you need to know pump flow at idling rpm's, cylinder bore diameter, piston rod diameter, and pressure settings/requirements to operate the bucket cylinder....

The difference between these two first options, is that the regen valve will let bucket dump at "full speed", while the restrictor will slow down the dump (the extension).....some times you want the dump go fast huh??!!

The third option is to throttle "hard" while dumping bucket....that way the pump will put out more flow to fill the void on the capped side....:laughing:

 

[handirifle]

What it is, is when I go to dump the bucket, often times (not always), it will travel about 3/4 of the way, then stop. It seems them I need to rev the engine a bit with the valves in neutral, then full left again, and the bucket completes the last bit of travel. Not sure what the term is for it, but the back of the bucket is rotating closer to me as I sit in the seat.

When in complete motion, the bottom of the bucket is near verticle. Otherwise it stops about 15-20deg short of that.

 

[AKKAMAAN]

What it is, is when I go to dump the bucket, often times (not always), it will travel about 3/4 of the way, then stop. It seems them I need to rev the engine a bit with the valves in neutral, then full left again, and the bucket completes the last bit of travel. Not sure what the term is for it, but the back of the bucket is rotating closer to me as I sit in the seat.

When in complete motion, the bottom of the bucket is near verticle. Otherwise it stops about 15-20deg short of that.

What make and model # is your loader??

This is one of the issues, where a little video clip that shows how your problem acts, could help to explain. Preferably from the side of the loader showing all the pivot points for bucket and cylinder....

Could you make a video clip and post it please??

Or find a video clip online that shows your FEL equipment doing this....