Dual 3PH Tilt Cylinders--Plumbed In Parallel?

[npalen]

Thanks for the great feedback, guys. It's always interesting to hear everyone's opinion.

 

[jmc]

Years ago there was a TBN thread started by a guy who had dual tilt cylinders on (I think) a Kubota 4400. They were plumbed thru one valve to maximize tilt angle on both sides of the implement. IE, when the left side went up, for example, the right side went down. Quite an improvement over one side always being fixed.

 

[npalen]

Years ago there was a TBN thread started by a guy who had dual tilt cylinders on (I think) a Kubota 4400. They were plumbed thru one valve to maximize tilt angle on both sides of the implement. IE, when the left side went up, for example, the right side went down. Quite an improvement over one side always being fixed.

Trying to wrap my brain around this. How would it be plumbed to prevent float?

 

[countrybumpkin]

They couldn’t move if the valve was closed, they were hooked rod end on one to base end on the other. So as the valve was opened it would extend one and retract the other, sort of like a snow plow blade.

 

[RickB]

Trying to wrap my brain around this. How would it be plumbed to prevent float?

It would use a master cylinder and a slave cylinder. They need to be sized appropriately and the master cylinder has a bleeder in the piston so the system can be phased. This particular application would be different from the typical master/slave setup in that the cylinders would be moving in opposite directions rather than the typical common direction. Tough to design and probably cheaper and easier to use two separate control valves and separate cylinders.

 

[BukitCase]

I have top-n-tilt on my old allis, ATM it's just plumbed thru a manual diverter from the ONLY remote the tractor has - I put a cylinder on the tilt that's a couple inches longer stroke than recommended, and with my 7' Gannon on I have a total 2' range at blade ends (either side can be either 12'' higher OR lower than the other -

works really well, but doesn't give me "floating tilt"...

When a few more projects get out of the way, I have a 4 valve stack that'll get inserted in front of the 3ph - 2 of the sections have float, 2 don't. If I ever add a SECOND tilt cylinder, I'll probably experiment with putting both tilts on their own (adjacent, floatable) valve - my thoughts are - with the 2 valves adjacent, I can hold BOTH handles in my palm; then the choice is either move both or one in either direction, or TWIST the pair either direction to tilt. Could also just put BOTH valves into float if desired.

Above would still leave me 3 OTHER remotes, the 2 new ones and the original single. Gannon has hydraulic rippers, plus I may later build a fully articulated rear blade.

If you're as much of a "mad scientist" as I tend to be, it's good to have options ... Steve

 

[downsizingnow48]

A lot of backhoes with dual swing cylinders are plumbed rod end to base end. I used that style of plumbing, but with a check valve, on my tilt coupler, which operates from one valve. The check valve keeps the bucket tilted where you put it.

 

[npalen]

A lot of backhoes with dual swing cylinders are plumbed rod end to base end. I used that style of plumbing, but with a check valve, on my tilt coupler, which operates from one valve. The check valve keeps the bucket tilted where you put it.

I'm thinking that is also how the angle cylinders on a snow plow blade are plumbed and they are connected mechanically. I'm trying to understand why a check valve is required. Is it a pilot operated check valve?

 

[downsizingnow48]

Yes it is a double pilot operated check valve. Without the check valve fluid is free to move between the two cylinders. Doesn't matter on a swinging backhoe boom. Does matter when you want to hold an angle for grading.

 

[npalen]

They couldn稚 move if the valve was closed, they were hooked rod end on one to base end on the other. So as the valve was opened it would extend one and retract the other, sort of like a snow plow blade.

I think that the difference between this and the way a snow plow blade angle is connected is that there is a mechanical connection on the snow blade. This prevents the cylinders from moving until the valve is actuated.

In the case of the 3PH double tilt cylinders, I don't think connected rod ends to base ends would work. I understand that shifting the valve spool would cause the two cylinders to travel in opposite directions which is the desired effect.

What I don't understand is the situation where both cylinders would be in midstroke and you let go of the valve handle. Looks like the weight of the 3PH attachment would just cause both cylinders to "droop" as the oil transferred from the base port of one to the rod port of the other and vice versa.

Edit: Or is this another instance of where the oil from the base of a cylinder can't transfer to its rod end if there is a leaky piston seal because the rod end is less volume? It's messin' with my brain.