snow plow hydraulics

[diesel466]

I have a question about using a loader valve to control single acting cylinders to angle plow. I thought that using a single acting cylinder on a valve set up for double acting was bad because it forced oil though relief valve? But it looks like it is done. Could someone please explain it. Thanks

 

[zzvyb6]

Two mechanically connected single cylinders act the same as a double acting cylinder. Oil in 1st one, oil out the second one.

This presumes you have two single actors on the plow blade.

 

[bcp]

If you had only one single acting cylinder, it would be power extension, no power retraction. Must use another cylinder, gravity, push against a tree, etc. to move the other direction.

Bruce

 

[LD1]

Two mechanically connected single cylinders act the same as a double acting cylinder. Oil in 1st one, oil out the second one.

This presumes you have two single actors on the plow blade.

Ditto.

A pair of SA cylinders function the same as a DA cylinder. (or in the loaders case, a pair of DA cylinders in parallel).

I assume you are wanting to use the curl function to control the plow angle.

Under normal operation, When the lever is pulled toward you (curl), fluid comes out one of the hoses on the valve, goes through a tee, and then to the rod side of the cylinder. All the while allowing fluid from the base end of the cylinder to return to the tank freely.

Same thing happens when dumping only reversed. Fluid comes out the other valve hose, goes through the tee, and into the base end of the cylinders, while allowing the fluid on the rod side to return to tank.

When hooking up a plow, you need to do away with the tee's. Which ever hose is under pressure when curling (joystick pulled left) needs to go straight to the RIGHT cylinder on the plow. The other curl hose off the valve needs to go to the LEFT cylinder on the plow.

So functionally, when pulling the stick left, you are putting fluid in the right angle cylinder allowing it to extend, and allowing fluid from the left cylinder to return to tank allowing it to collapse, thus angling the plow left. The opposite would happen when the stick is pushed right.

I also need to caution you that you need to install a crossover relief valve in there between the loader valve and the angle cylinders.

 

[J_J]

I have a question about using a loader valve to control single acting cylinders to angle plow. I thought that using a single acting cylinder on a valve set up for double acting was bad because it forced oil though relief valve? But it looks like it is done. Could someone please explain it. Thanks

If you use a DA valve to control a SA cyl, you plug one work port and use the other work port for flow in developing pressure and gravity out low pressure.

Since the other work is lugged, the valve will bo into relief until the gravity down is finished.

The other option is to use the one work port and run a hose from the unused work port to tank. The relief will not activate.

Although you can operate two SA cyl from a DA valve, the regen on the right lever will not allow movement. Stay out of regen and it will work.

Some tractors only have regen to the bucket dump and therefore can not work a SA cyl.

 

[diesel466]

Thanks for the quick replies! So as along as SA cylinders are used in pairs it works fine, It is when trying to use a single SA cyinder with a valve set up for a DA cylinder it is a problem? Am I understanding that right? Thanks

 

[J_J]

That is correct unless you have a spring assisted cyl.

 

[diesel466]

Thanks J.J.

 

[Fallon]

Just make sure your valve doesn't have regen (common if you are borrowing your bucket dump circuit). Regen will dump full pressure to both cylinders. It won't hurt anything but you will go nowhere. If your valves has both regen dump & power dump you'll be fine if you find the power dump position.

 

[Dan W]

Just make sure your valve doesn't have regen (common if you are borrowing your bucket dump circuit). Regen will dump full pressure to both cylinders. It won't hurt anything but you will go nowhere. If your valves has both regen dump & power dump you'll be fine if you find the power dump position.

i believe you are right Fallon,
i learned this the hard way when trying to connect twin single acting cylinders for plow swing function and one double acting cylinder for the plow lift. My blade would slam one way and lock up solid in that position, i couldn't figure this out, drove me crazy for a while. live and learn. TBN was very helpful to me when i discovered several discussions regarding loader regenerative hydraulic circuits used on almost all loader valves. make a long story short, i bought a twin stick valve at Princessauto, ($179) and all was well.
i did some research on this topic and found out that a regenerative function is used on most loaders for bucket dump control (preventing a slam down situation when dumping heavy loads). basically oil is fed to the back side of the dump cylinders to prevent oil evacuation or cavitation when dumping a heavy loaded bucket thereby controlling the dump action.

i'm no expert on this, but finally came to the conclusion that a new valve was required.

my 2 cents worth..

Dan

 

[Fallon]

Regen makes things fast at the expense of power. It applies full pressure to both the rod & cylinder ends of a DA cylinder. As the cylinder end has more surface area than the rod end, it wins the fight. The fluid from the rod end gets forced into the cylinder end. This is advantageous if the pump can't keep up. Such as in the case when dumping your bucket & gravity already wants to do all the work for you. You don't need the power & if it dumps slow, it can end up sucking in air into the cylinder past the seals.

Some have both power dump & regen dump at the start or end of the spool. Some only regen.