Comparison LS XG 3140 HP specs are wrong

   / LS XG 3140 HP specs are wrong #12  
polemidis said:
wtf, I did the calculations in ft. lbs and it sounds good to me too. where am I screwing up? My calculations on my 1st post in Nm still look fine! argggg.

What I am really trying to find is the size/timings of the cylinders for a backhoe that I am designing. And I want to make a good estimation on the hp availabilty and if it worth to use a pto pump instead of the remotes.
Click to expand...

I'm not really sure what you mean by that. Listed pump flow for the XG3140 is 8.2GPM. Listed PTO HP is 32.

Here's a calculator that tells you how much HP you need to get a specific flow at a specific pressure:

Hydraulic Pump Calculations - Womack Machine Supply Company

Basically, you can get 16GPM to 2,700 PSI with 30.25HP. You would need a pump with 6.82ci displacement.

So you could have double the flow of the tractor outlets by using a PTO pump and still achieve a reasonable pressure...

Is that the info you were looking for?

They don't make 6.82ci pumps, at least not ones I could readily find.

Here's a 7.62ci one, which would be 17.81GPM at 2500psi.

7.62 cu in 16.6 GPM 54 RPM Dynamic GP-PTO-A-7-6-S Hydraulic PTO Pump | Dynamic | Brands | www.surpluscenter.com
 
   / LS XG 3140 HP specs are wrong #13  
   / LS XG 3140 HP specs are wrong
  • Thread Starter
#14  
TheMadOne said:
I'm not really sure what you mean by that. Listed pump flow for the XG3140 is 8.2GPM. Listed PTO HP is 32.

Here's a calculator that tells you how much HP you need to get a specific flow at a specific pressure:

Hydraulic Pump Calculations - Womack Machine Supply Company

Basically, you can get 16GPM to 2,700 PSI with 30.25HP. You would need a pump with 6.82ci displacement.

So you could have double the flow of the tractor outlets by using a PTO pump and still achieve a reasonable pressure...

Is that the info you were looking for?

They don't make 6.82ci pumps, at least not ones I could readily find.

Here's a 7.62ci one, which would be 17.81GPM at 2500psi.

7.62 cu in 16.6 GPM 54 RPM Dynamic GP-PTO-A-7-6-S Hydraulic PTO Pump | Dynamic | Brands | www.surpluscenter.com
Click to expand...

You are exactly right!! But, the problem with these calculators is that they assume that the torque is constant as in a electric motor. With a gas or diesel engines thats not the case and one has to downsize the pump in order to actually handle the load. But another reason that I went deeper into this is because I do not want to run the tractor at the max power (at @2600 rpm) but at just above its max torque @1800, which conveniently will be more quiet too. I concluded that despite the fact that the 7.62ci is just above my tractor limits at 2600rpm(with a safety factor added) , its adequate to use at 1600 rpm, because the torque is higher (and hopefully at 1800rpm too.)
I am pretty sure that I will go with the 7.62ci. At 1800rpm I get 387rpm at the pto, 12gpm with the 7.62ci.
And the last reason is to see if I can make the backhoe stronger with wider cylinder bores. The stock LS backhoes are using 2.5" cylinders. If I can go with 3" without sacrifice speed, why not. I can also make longer backhoe.
Anyway it will take a while I just started a rough design 3 days ago :) :)

Screenshot from 2019-03-22 17-02-59.png
 
   / LS XG 3140 HP specs are wrong
  • Thread Starter
#16  
   / LS XG 3140 HP specs are wrong #17  
MHarryE said:
https://www.cm-labs.com/vortexstudi...tion/Content/Editor/editor_vs_torqueTable.png

You do realize that if you set your tractor to run at 1800 rpm with 2600 being high idle, you will be working on a different power curve as illustrated by this graph.
Click to expand...

Another thing to consider is that running a lot at 1800 rpm is going to cause way more regen cycles than running over 2k. When I bought my tractor last year, my first project was lots of backhoe work. I ran 16-1800 rpms for most of it, and hit my first regen at only 18hrs. I bumped up the throttle to 2200ish, and didn't trigger another regen until 63hrs. Just an example, and something else for you to consider.
 
   / LS XG 3140 HP specs are wrong
  • Thread Starter
#18  
NYCheese said:
Another thing to consider is that running a lot at 1800 rpm is going to cause way more regen cycles than running over 2k. When I bought my tractor last year, my first project was lots of backhoe work. I ran 16-1800 rpms for most of it, and hit my first regen at only 18hrs. I bumped up the throttle to 2200ish, and didn't trigger another regen until 63hrs. Just an example, and something else for you to consider.
Click to expand...

Thanx man! My regen periods are at about 50hrs, so far and I used the tractor mostly for log skidding or snow plowing. No standard rpm though. Maybe the contanst rpm on backhoe work makes it worse. Thank you , I will keep it in mind.
 
   / LS XG 3140 HP specs are wrong
  • Thread Starter
#19  
I wonder how I could change the subject since it is misleading. It was my error in the calculations I do not want to spread any fake news! :)
 
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