What GPM hydraulic pump is needed for 2" bore cylinder?

[AKKAMAAN]

Boy I am glad I replied to this thread. It is now in my "subscribed" list and It will be easier to find when I need one of these charts. Shure beats doing it by hand or creating another spread sheet:thumbsup::thumbsup:

Glad you liked it LD1....let me know if you get stuck in your own "spread SHEETING".....and don't be afraid to share your own....I am sure I'll learn something too...
Here is my hoze sizing spread sheet, instead of using a ruler across the computer screen, on an online nomogram....

 

[LD1]

Glad you liked it LD1....let me know if you get stuck in your own "spread SHEETING".....and don't be afraid to share your own....I am sure I'll learn something too...
Here is my hoze sizing spread sheet, instead of using a ruler across the computer screen, on an online nomogram....

I don't know how to share them, and if so, I doubt you would be able to learn anythign from me.

All I know is how to input the formulas and make it give me a result. To me, it is just like an elaborate calculator. Trying to create a spreadsheet is worthless unless you actuall know how to do it long form and knowing the formulas. And not the excel formulas. I mean the formulas for what you are actually working on.

I also have a few basic ones set up for both my water and electric bill. Each month I input my usage (gallons or kwh) and my total bull and it gives me how much I pay per gallon/kwh. It is nice cause I have been doing it for 4 years now and I can compare my usage with years past. And I can also see when rates go up as well as yearly totals.

Ok, enough hijacking for now.

 

[David Devuono]

So I am reading all this and wondering what the answer is to Chads question. If he uses 5GPM, the boom will move very quickly ( approx 1.5 seconds to retract or extend). On the other hand, it would be nice to have the flow to operate more then one cylinder. A lot of the homebuilt backhoes I see on Youtube are almost too fast to control. What is a reasonable cylinder speed. When we know that, we can size our pumps appropriately?

thanks

 

[chad22]

If you are talking about a small backhoe I would think 5 gallons per minute is about right.
Any pics of the placement of the cylinder would be helpful.
Craig Clayton

There's a pic in this thread about my backhoe. My homemade backhoe made from a riding mower - Page 3 - TractorByNet.com

I updated it with a few pictures.

Thanks everyone for the help.

Chad

 

[LD1]

So I am reading all this and wondering what the answer is to Chads question. If he uses 5GPM, the boom will move very quickly ( approx 1.5 seconds to retract or extend). On the other hand, it would be nice to have the flow to operate more then one cylinder. A lot of the homebuilt backhoes I see on Youtube are almost too fast to control. What is a reasonable cylinder speed. When we know that, we can size our pumps appropriately?

thanks

I think the 5 GPM pump with those cycle times will be just fine.

Remember, you can feather the control lever and achieve whatever speed you want. Or you could just idle down a bit.

But when doing backhoe work, more often than not, you are using 2 or 3 functions at the same time. Like curling the bucket athe the same time you are extending the dipperstick cylinder at the same time raising the main boom.

And the swinging the boom at the same time you are extending the dipperstick at the same time dumping the bucket.

If you sized the pump to have a more moderate flow for only one function, trying to control more than one thing will be ungodly SLOW.

 

[Redneck in training]

I think the 5 GPM pump with those cycle times will be just fine.

Remember, you can feather the control lever and achieve whatever speed you want. Or you could just idle down a bit.

But when doing backhoe work, more often than not, you are using 2 or 3 functions at the same time. Like curling the bucket athe the same time you are extending the dipperstick cylinder at the same time raising the main boom.

And the swinging the boom at the same time you are extending the dipperstick at the same time dumping the bucket.

If you sized the pump to have a more moderate flow for only one function, trying to control more than one thing will be ungodly SLOW.

Doesn't it depend on what hydraulic system you use? I think most commercial BHs use some flavor of closed center system with variable delivery pump or pumps. Most home made BHs use open center system with constant delivery pump. You can operate several cylinders to some degree too as long as the first cylinder is moving the second will move too. Speed doesn't depend on how many cylinder you operate but the force does. In closed center system speed and force stays same until you max out the pump flow.

 

[LD1]

Doesn't it depend on what hydraulic system you use? I think most commercial BHs use some flavor of closed center system with variable delivery pump or pumps. Most home made BHs use open center system with constant delivery pump. You can operate several cylinders to some degree too as long as the first cylinder is moving the second will move too. Speed doesn't depend on how many cylinder you operate but the force does. In closed center system speed and force stays same until you max out the pump flow.

You lost me

Are you saying that in a homemade "open center" system that adding cylinders doesnt chacge speed but it somehow lowers the force to each cylinder????????

 

[J_J]

The pressure will be the same, therefore the force on the cyl will be the same. Speed will be determined by the number of cyl operating, and lever position.

 

[LD1]

The pressure will be the same, therefore the force on the cyl will be the same. Speed will be determined by the number of cyl operating, and lever position.

Thats what I was thinking too.

 

[Redneck in training]

The pressure will be the same, therefore the force on the cyl will be the same. Speed will be determined by the number of cyl operating, and lever position.

I think that the the first cylinder will have less force due to back pressure from the second cylinder. Therefore I think the force will be someway divided depending on lever position and/or the load on each cylinder.
Am I seeing it right. Are the cylinders in series. Is oil from first going to second etc?