Snowblower Hydraulic Chute movement question

[imarobot]

I have an L2195A Snowblower with the hydraulic chute. To turn the chute to the left I move the loader control lever to the left. To move the chute to the right I have to push the lever all the way to the right past the detent to get the chute to move.
Why does it work this way? I would thing just moving the lever without going past the detent should work.

 

[Kennyd4110]

Short answer: Regen or the regenerative function of the loader valve.

Longer answer is in many threads via these search results:

Search results for query: regen

www.orangetractortalks.com

Regen is a "feature" of most modern FEL (Front End Loader) valves, it's on the Dump (joystick far right) circuit, and is also referred to as "Fast Dump". The reason it is nice to have is that without it, the weight of a filled bucket can actually "pull" the bucket down faster then the fluid can enter the other side of the cylinder, this will create a air pocket and give the bucket a "floppy" feeling until the joystick is held in the dump mode a few seconds to refill the cylinder pushing the air past the seals. So we add "regen" or "regenerative" function to the valve.

Regen solves this problem by actually filling both sides of the cylinder at the same time with hydraulic fluid. But how will that work you might ask? Well, because there is more volume on the side of the cylinder that extends it since the rod is taking up space in the other side, it "overpowers" the rod side and lets the cylinder extend-thereby dumping the bucket. So since now both sides of the cylinder are "pressurized", the air pocket can not develop, eliminating the "floppy" bucket syndrome. One other added bonus is that the bucket actually dumps faster due to the higher flow rate required to do all this, that's why it's referred to as "fast dump" sometimes.

So, now you may be asking “This is cool and all that, but why do I need to know about it?” The answer to that is simple, if you ever try to run a snow plow with two SA (single acting) cylinders, or a cylinder that drives a chute rotator on a snowblower you will soon find out that they won’t work if you push the joystick to far right in the regen mode. The plow won’t work because since both lines are pressurized-both cylinders will be trying to extend at the same time binding everything up. The rotator won’t work because there is no weight pushing the cylinder closed like there is on the loader.

 

[imarobot]

Thanks for the search query, didn't know about regen mode and I learned a lot there.
My understanding of how it works, and please correct me where I'm wrong.
When pushing the loader to the left there is no regen mode so the chute motor can easily rotate because there is no hydraulic fluid directed back into the other side of the chute motor so the motor can freely rotate in that direction.
When pushing the lever to the right the renen mode is activated keeping hydraulic pressure on both sides of the motor. Since there is nothing to assist the motor in turning (as in dumping a bucket) the motor does not move. Pushing the lever past the detent disables the regen mode and with fluid only being on one side of the motor it will turn.
So, to work without having to use a detent position, the valve would not have a regen mode.
I'm assuming if I reversed the hydraulic hoses, turning the chute to the left by pushing the lever to the right would require going past the detent to get it to turn left. This thought clears up in my little brain that the reason this works the way it does is with the valve and not something in the chute motor.
I have a couple more questions about this, but will wait to see how much of this I have wrong

 

[TheOldHokie]

Thanks for the search query, didn't know about regen mode and I learned a lot there.
My understanding of how it works, and please correct me where I'm wrong.
When pushing the loader to the left there is no regen mode so the chute motor can easily rotate because there is no hydraulic fluid directed back into the other side of the chute motor so the motor can freely rotate in that direction.
When pushing the lever to the right the renen mode is activated keeping hydraulic pressure on both sides of the motor. Since there is nothing to assist the motor in turning (as in dumping a bucket) the motor does not move. Pushing the lever past the detent disables the regen mode and with fluid only being on one side of the motor it will turn.
So, to work without having to use a detent position, the valve would not have a regen mode.
I'm assuming if I reversed the hydraulic hoses, turning the chute to the left by pushing the lever to the right would require going past the detent to get it to turn left. This thought clears up in my little brain that the reason this works the way it does is with the valve and not something in the chute motor.
I have a couple more questions about this, but will wait to see how much of this I have wrong

You have the basics.

Reversing the hoses on a motor has no effect

Reversing the hoses on a cylinder will make it extend in both postions.

Dan

 

[Russell King]

Could you use the valve and hoses for curl (assuming there is no regen in the curl circuit)?

 

[TheOldHokie]

Could you use the valve and hoses for curl (assuming there is no regen in the curl circuit)?

He needs to go both durections.

Dan

 

[imarobot]

You have the basics.

Reversing the hoses on a motor has no effect

Reversing the hoses on a cylinder will make it extend in both postions.

Dan

This confuses me. I would have thought if I reversed the hoses this would cause the motor to work in the opposite direction relative to the lever direction. There goes one of my understandings of this

 

[TheOldHokie]

This confuses me. I would have thought if I reversed the hoses this would cause the motor to work in the opposite direction relative to the lever direction. There goes one of my understandings of this

I phrased that poorly so my bad

Reversing the hoses will run the motor in the opposite direction but it will still stsll in the other.

Swapping the hoses on a cylinder will cause the cylinder to extend in BOTH directions.

The description of regen you read was not ezactly right....

Dan

 

[imarobot]

Got it, thank you, I was just focusing on the motor, not a cylinder. So, there's still hope for me to understand this!
I've never delved into the would of hydraulic components and am trying to learn it all. I still haven't figured out the symbols in a hydraulic system diagram, so I have a hard time following the diagram.
But I'm working at it, and thanks to all the info I gain on this site I may get it someday! Just trying to get there before my brain discharges and can no longer be charged.

 

[TheOldHokie]

Got it, thank you, I was just focusing on the motor, not a cylinder. So, there's still hope for me to understand this!
I've never delved into the would of hydraulic components and am trying to learn it all. I still haven't figured out the symbols in a hydraulic system diagram, so I have a hard time following the diagram.
But I'm working at it, and thanks to all the info I gain on this site I may get it someday! Just trying to get there before my brain discharges and can no longer be charged.

Would you like a more precise description of how a regenerative spool works?

Dan

 

[imarobot]

Would you like a more precise description of how a regenerative spool works?

Dan

Please!!!

 

[TheOldHokie]

Please!!!

Here you go. This is the flow path in the regenerative section of the spool. Notice that A is connected to base end of the cylinder. This is crucial for correct operation of the valve and cylinder.

Incoming pump flow goes out A and into base end of cylinder. BUT - the return port B is not connected to tank as is usual. Instead it is looped back to A. Now both sides of the piston are at the same pressure but the rod end has a smaller surface area creating a force imbalance on the piston that extends the rod. Oil coming in B is looped back to A with the effect of increasing the flow rate and extend speed but force is reduced by the ratio of the two areas.

STUDY QUESTION

What happens if A is connected to rod end and B is connected to base end. The answer is not intuitive.

 

[imarobot]

I'm guessing, but I think the would not move because the base has a larger surface area, or move very slowly???

 

[TheOldHokie]

I'm guessing, but I think the would not move because the base has a larger surface area, or move very slowly???

Like I said this is not intuitive

Reversing the connections does not change the operation of regen becsuse the ports are looped together inside the valve and conditions at the cylinder are exactly the same.

What it does change is the operation of retract. With the connections reversed the retract port (B) is now connected to the base end of the cylunder. When the spool is shifted to retract pressure is applied to the base end of the cylinder, the rod end port (A) is connected to tank, and the cylinder is extended. You have lost the retract function.

Fun with physics !!!

Dan

 

[PoTreeBoy]

Here you go. This is the flow path in the regenerative section of the spool. Notice that A is connected to base end of the cylinder. This is crucial for correct operation of the valve and cylinder.

View attachment 158991

Incoming pump flow goes out A and into base end of cylinder. BUT - the return port B is not connected to tank as is usual. Instead it is looped back to A. Now both sides of the piston are at the same pressure but the rod end has a smaller surface area creating a force imbalance on the piston that extends the rod. Oil coming in B is looped back to A with the effect of increasing the flow rate and extend speed but force is reduced by the ratio of the two areas.

STUDY QUESTION

What happens if A is connected to rod end and B is connected to base end. The answer is not intuitive.

Looks like subject for a tutorial. (Inside joke, TOH will get it.)

 

[imarobot]

Like I said this is not intuitive

Reversing the connections does not change the operation of regen becsuse the ports are looped together inside the valve and conditions at the cylinder are exactly the same.

What it does change is the operation of retract. With the connections reversed the retract port (B) is now connected to the base end of the cylunder. When the spool is shifted to retract pressure is applied to the base end of the cylinder, the rod end port (A) is connected to tank, and the cylinder is extended. You have lost the retract function.

Fun with physics !!!

Dan

I gotta chew on this one for a while...

 

[TheOldHokie]

I gotta chew on this one for a while...

Its a chewy one. I am out right now. If you have not digested this by the time I get home I will post some visual aids.

Dan

 

[TheOldHokie]

Looks like subject for a tutorial. (Inside joke, TOH will get it.)

Are you offering to negotiate a publishing rights deal?



Dan