Backhoe Dipper-stick Down-Pressure Specification

[witel]

What specification parameter identifies the down-pressure of the working-end of the dipper-stick on a backhoe? For instance, if I had a hydraulic post-hole-digger or auger mounted on the backhoe, I'd like to know what kind of digging-force I'm dealing with so I can spec the PHD accordingly. I've noticed that different tractor and backhoe manufacturers have different names for some of the specs -OR- the specs may even be incomplete.

 

[john_bud]

What specification parameter identifies the down-pressure of the working-end of the dipper-stick on a backhoe? For instance, if I had a hydraulic post-hole-digger or auger mounted on the backhoe, I'd like to know what kind of digging-force I'm dealing with so I can spec the PHD accordingly. I've noticed that different tractor and backhoe manufacturers have different names for some of the specs -OR- the specs may even be incomplete.

There are many specs on BH's to tell their performance. Most have to do with the digging depth for flat bottoms of various lengths at certain depths. Others have to do with ability to dig a vertical wall opposite the tractor. Digging specs have to do with the boom and dipper stick's ability to power into the ground. But that is a lateral force, not straight down, it is more straight at the tractor. The other digging force is related to the curl power of the bucket cylinder.

If I understood your question, you are wanting to know how much force the BH can put in a straight down direction, right? That is going to be limited to the weight of the BH + weight of the back of the tractor. If the BH pushes down any harder, the tractor will just go up in the air, the BH won't go down any harder. Obviously, fill the tires, add wheel weights to make that weigh as much as possible. With that said, I have never seen that type of spec written as it isn't what typical BH operators use (nor want to know). For your purpose, just add the BH weight and 1/2 the bare tractor weight and any tire fill weight and any wheel weights. Should be close.

jb

 

[witel]

If I understood your question, you are wanting to know how much force the BH can put in a straight down direction, right?

Right.

That is going to be limited to the weight of the BH + weight of the back of the tractor. If the BH pushes down any harder, the tractor will just go up in the air, the BH won't go down any harder.

I agree. No question there.

I would think that it sure would be nice if there WAS a spec on the straight-down force ability of a BH ... assuming that it is attached to a rigid structure that will not lift from the ground. The force would be related to the BH weight and the strength of the BH hydraulics.

So, can anyone elaborate on some other BH specs? For example (only an example of one manufacturer), the JD 110TLB has only the following specs on their web-site:

Digging Force-Crowd = 3764 lb.
Digging Force-Bucket = 5723 lb.
Side Swing Force = 7,975 lb./ft.
Boom Lift Capacity at Ground Level = 1216 lb.
Dipperstick Lift Capacity at 8-ft. above ground = 1499 lb.​

What is the "Digging Force-Crowd"? Another manufacturer may have a different suite of specs. Why aren't there more specs for such a complex and powerful implement?

 

[LarryRB]

If your wanting a PHD on the end of your backhoe. the most important spec you need is the hydraulic fluid spec.. Does your tractor put out 9 GPM, 20 GPM?... Hydraulic post hole diggers are geared to the GPM.. Whether your dipper or crowd has 5000# or 500# is secondary to GPM and secondly lift capacity., AS the 110 deer, 1200 #, a good hydraulic PHD that fits backhoe dipper stick probably needs 10GPM and weighs 700# or so.

 

[dirtworksequip]

witel, John_Bud gave you some right on facts about what you are trying to figure out. The spec you want isn't going to be found though........because it has no use in a working application.As John stated, the down force can't exceed the weight of the machine. I know you are trying to factor in the hyd. power,but it just doesn't work that way.


There are two types of digging techniques with a hoe.
1) Bucket: that is digging by curling the bucket towards the machine and filling the bucket.
2) Stick: that is digging by pulling the stick in towards the machine and filling the bucket.
Hope you understand my description of the difference.

Digging force-crowd: is the digging force at the bucket that is generated by stick digging.

 

[dirtworksequip]

Here's a description and drawing of the two types of digging techniques.



http://i138.photobucket.com/albums/q259/dirtworksequip/deere backhoe/P1010953.jpg

 

[john_bud]

Right.


I agree. No question there.

I would think that it sure would be nice if there WAS a spec on the straight-down force ability of a BH ... assuming that it is attached to a rigid structure that will not lift from the ground. The force would be related to the BH weight and the strength of the BH hydraulics.

So, can anyone elaborate on some other BH specs? For example (only an example of one manufacturer), the JD 110TLB has only the following specs on their web-site:

Digging Force-Crowd = 3764 lb.
Digging Force-Bucket = 5723 lb.
Side Swing Force = 7,975 lb./ft.
Boom Lift Capacity at Ground Level = 1216 lb.
Dipperstick Lift Capacity at 8-ft. above ground = 1499 lb.​

What is the "Digging Force-Crowd"? Another manufacturer may have a different suite of specs. Why aren't there more specs for such a complex and powerful implement?

As others have said, the specs that BH operators are interested in are the operational specs, the hydraulic flow, pressure, and the physical specs of the machine. How wide, tall, long, heavy etc.

By the way, the down force (theoretical maximum) is going to be greater than the lift force. The cylinders use the side with the area reduced by the rod (typically) to lift and the side with full diameter for digging.

If you are getting a hydraulic PHD, just make sure that the hoe can lift it, can position it and has the hydraulic capacity to run it. Less flow is less speed and less power. Since most PHD's are designed to self pull while digging, you don't need to "lean on them" to get them to work. Although that helps in hard pack soils!

jb

 

[MarkV]

I’ve never seen the specs you are looking for on a backhoe. Most likely the best info you will get is to compare the hoe’s lifting capacity at full extension. For example the Kubota L-39 has a lifting capacity of about 575 lbs. at full extension and 6’ off the ground. It would be safe to assume that the down force in the same situation would be better than that.

Down force is an advantage with a PHD yet if the auger is not biting and pulling itself into the ground there is a limit of what down force is going to do. You are not going to drill rock with the wrong bit regardless of how much down force you have. The real advantage to a hydraulic auger is the ability to reverse itself and unscrew from the hole. Those who have let a 3pt auger go too deep with out clearing the spoils know it is not fun to unscrew an auger by hand when the tractor can’t lift it out.

MarkV

 

[witel]

Thanks, Everyone. In a round-about way my fears have been eased.

TBN and all of you are great!

 

[witel]

For example the Kubota L-39 has a lifting capacity of about 575 lbs. at full extension and 6’ off the ground.

MarkV, out of curiosity, where are you finding this specification? I only have the L39 brochure. Do you have more detailed specifications that you can pass along?