How do you calculate digging force requirements?

jgibbens · Mar 7, 2012

Is there a guideline for calculating the amount of force needed to push a digging implement into different types of soil?

Depmandog · Mar 7, 2012

http://www.tractorbynet.com/forums/attachments/110008-calculate-bucket-pryout-force.html

You might review this old thread to see if this points you in the right direction

Good luck.

jgibbens · Mar 8, 2012

I need the other side of the equation. How much force does it take to push an implement into the ground? I'm almost finished with a hydraulic tree spade and took it out for a test run last night. The spade uses 2" bore cylinders to push blades made from 19" diameter pipe. They dig in about a foot before the hydraulics start to bypass. I really wasn't expecting 7,000 lbs of force to be insufficient so now I need to figure out how much force it should take before I buy larger cylinders.

rambler · Mar 8, 2012

I can't help you, but interesting situation/ topic.

You are getting through the topsoil, hitting the subsoil. Often (here anyhow) the subsol is hard undisturbed yellow clay, very hard to push through. Amount of moisture also makes a big difference, right now it's probably like jelly. In August, it's probably like concrete.

Hard to get a real number, as it changes so much?

--->Paul

Depmandog · Mar 8, 2012

I am pretty sure that I recall watching a program where a very large Semi mounted tree spade used water as a lubricant on the actual spades. The water was a critical part of the process. Without the water they couldn't get the depth of penetration needed.

http://www.treeservicesmagazine.com/print-2221.aspx

swick1 · Mar 8, 2012

That's true. If you try to push a grounding rod in by hand, you can't do it obviously. If you do the same thing and fill the hole with water while you wiggle it, you can drive a 6' grounding rod all the way into clay by hand. I've done it!

I'd look into using a small sprayer pump and reservoir with some perforated tubing wrapped around the tool to lubricate it.

strum456 · Mar 8, 2012

swick1 said:
That's true. If you try to push a grounding rod in by hand, you can't do it obviously. If you do the same thing and fill the hole with water while you wiggle it, you can drive a 6' grounding rod all the way into clay by hand. I've done it!

I'd look into using a small sprayer pump and reservoir with some perforated tubing wrapped around the tool to lubricate it.

Sounds like a good idea to me. I don't know what you have this thing attached to, but it sounds like something needs to change or else you are going to need a REALLY heavy tractor.

Baby Grand · Mar 8, 2012

A little vibration can help with soil penetration. I'm thinking maybe a small eccentric spinning weight attached to the digger frame. Combine that with the water spray and you might have performance that meets your expectations.