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View Full Version : Grading a road, mid blade???


Mith
04-17-2007, 10:23 AM
Anyone have any thoughts on the use of a belly blade for grading and reshaping a road/track?
I have only heard of box blades and rear blades for this purpose.

I was thinking about the possibility of making a mid mount grader blade, that it might be easier to get a smoother surface using one, afterall, those motor graders use mid blades?

Anyone have any thoughts or experience on this?

http://www.grouser.com/products/bellyblades/images/grader1.jpg

Grouser belly blades (http://www.grouser.com/)

larryRB
04-18-2007, 08:28 AM
the "grouser" brand is a small copy of a regular grader., I have run a Champion 14 ft articulated grader and it is the various options available to angle blades for certain results, certain conditions and the fact that one can see what they are doing as they go along. The wider the blade, the easier it is to screed a road. I haven't tried a grouser system but think it should work quite well.

Wannafish
04-18-2007, 08:39 AM
No experience, but I do have a thought. One reason for the blade under the center of the machine is that it can utilize the entire weight of the machine for down pressure. The Grouser looks like it would work well.

Good Luck!

DaveNay
04-18-2007, 12:38 PM
I was thinking about the possibility of making a mid mount grader blade, that it might be easier to get a smoother surface using one, afterall, those motor graders use mid blades?

Anyone have any thoughts or experience on this?

I think you would have a very difficult time creating a level grade. Yes, motor graders use a mid blade, but most importantly, they have an extremely long wheel base. The long wheelbase minimizes the height change of the blade due to bumps in the ground. When you front wheels go over a bump, it lifts the blade, and you drop some material. When the rear wheels go over the material you just dropped, you again raise the blade and drop some more material. In effect, you can create a washboard effect on your ground with a short wheel base. Obviously, this is not what you wanted. :D

Mith
04-18-2007, 02:08 PM
Dave, would you not have the same problem with a rear or front mount blade though? Front wheels go over a bump, the rear blade digs in, or a front blade would lift up.

I wonder if the Grouser blades have a float function, that might avoid the blade lifting and releasing material when the wheels go over bumps?

Wannafish
04-18-2007, 02:26 PM
I think you would have a very difficult time creating a level grade. Yes, motor graders use a mid blade, but most importantly, they have an extremely long wheel base. The long wheelbase minimizes the height change of the blade due to bumps in the ground. When you front wheels go over a bump, it lifts the blade, and you drop some material. When the rear wheels go over the material you just dropped, you again raise the blade and drop some more material. In effect, you can create a washboard effect on your ground with a short wheel base. Obviously, this is not what you wanted. :D

Dave,

When you have a blade sticking out behind the rear wheels the effect you just described is exagerated (sp?) compared to what it would be if the blade is in the center of the wheelbase.

Example
Rear Tire dia.: 24"
Front Tire dia.: 14"
60" wheelbase (front to rear...or rear to front if you prefer)
A. Blade extending out 42" from center of rear tire
B. Blade at centerline of Wheelbase
C. Blade extending out 24" from C/L of front tire

Front tire goes over a 3.15 inch "bump" (3 deg. incline over the length of the wheel base):
Rear blade will go down 2.18".
Blade in the center of the wheelbase, the same bump will produce a movement of 1.59 inches (although the movement will be in the other direction - up instead of down).
This equates to ~37% greater blade movement with a rear blade, as opposed to a center blade.
To make a fair comparison, I also calculated the movement of a front blade that sticks out 24 inches in front of the center of the front tire, and it moves 4.41 inches upward (which would be even harder to control).

Now, if you can make sense of what I wrote (not suggesting you aren't able to...only that sometimes I ramble...) does it make sense that a center mounted blade would leave less material to...? :pat:
Ahhhhh. Maybe I see a glimmer of light in my otherwise darkened mind. The rearblade would leave NO gravel for the rear wheels to run over.

Hmm. After all the work I put into this post, no mere facts are going to dissuade me from posting it!

OMG! I sound like some at TBN think:hide2: !

Disclaimer: Your inches of movement may vary based on tire size, wheelbase, and distance of backblade to center of rear wheel.

DaveNay
04-18-2007, 02:39 PM
When you have a blade sticking out behind the rear wheels the effect you just described is exagerated (sp?) compared to what it would be if the blade is in the center of the wheelbase.

Dave, would you not have the same problem with a rear or front mount blade though?

Absolutely correct. If I were to rank the effectiveness, I would say:


Long wheelbase road grader with mid blade (actually, I think they are more like 1/3 from the rear.)
Short wheelbase tractor with mid blade.
Short wheelbase tractor with rear blade.I'm not sure the improvement from a rear blade tractor to a mid blade tractor is worth the premium price.

DaveNay
04-18-2007, 02:42 PM
To make a fair comparison, I also calculated the movement of a front blade that sticks out 24 inches in front of the center of the front tire, and it moves 4.41 inches upward (which would be even harder to control).

Ideally, this has no effect because your wheels are always on the finished surface, and there is no movement of the front blade. I doubt it ever really works this way though. :pat:

Ahhhhh. Maybe I see a glimmer of light in my otherwise darkened mind. The rearblade would leave NO gravel for the rear wheels to run over.

This is true on the first pass, but when you turn around and make a second pass, not only do you have a bump for your front wheels to go over, but it is immediately followed by a dip below grade. D'OH!

Wannafish
04-18-2007, 02:49 PM
This is true on the first pass, but when you turn around and make a second pass, not only do you have a bump for your front wheels to go over, but it is immediately followed by a dip below grade. D'OH!

Right...so it would average out.
3" high - level with grade - 3" low - level with grade - 3" high - level...

Gee. I wonder why that sounds just like my driveway. Maybe there's a correlation?

DaveNay
04-18-2007, 03:08 PM
Right...so it would average out.
3" high - level with grade - 3" low - level with grade - 3" high - level...


Sounds suspiciously like the wash boarding I described in my first post. :poke:

Wannafish
04-19-2007, 05:59 AM
Sounds suspiciously like the wash boarding I described in my first post. :poke:


Guess I'm never to old to learn...:alc: