Newbie -how does a tractor maintain down force on a scrapper?

[Egon]

The three point hitch made ag tractors practical. It was invented over a period of time in the 1920's and multiple USA patents awarded to Harry Ferguson the inventor beginning in 1926.


Practical, you mean the drawbar is no longer used?

Just wondering, have you seen a three point baler in action?

 

[RalphVa]

You can adjust the tilt of the blade to achieve "bite" or no bite. You could also put a 4x4 or concrete block on top of the blade.

Ralph

 

[flusher]

I am a newbie about ready to purchase my first tractor. My main application is for grading a 3 km laneway with the road bed made from pit run.

I am trying to figure out how down pressure is maintained on the scraper. Is it the weight of the tractor through the 3 pnt hitch, or is it simply the weight of the scrapper itself? Does a heavier tractor or ballast in my tires allow me to cut deeper into the roadbed?

Newbie in canada

Here's how downforce is applied to this float-type scraper--hydraulics

 

[jinman]

Bstarn, welcome to TBN. Your MX5100 does not have downforce on the 3PH. It relies on the weight of the implement and cutting angles of blades to scrape. Moisture content and materials composition are two big determining factors for cutting depth. Any downpressure on the 3PH would translate to lift on the rear wheels and reduce traction force. You want your tractor to always maintain optimum traction, thus the big rear wheels and lugs. Many boxblades also contain scarifier teeth to break up hardpan soil or dislodge surface growth. A rear blade on a tractor will never achieve the cutting/grading ability of front blade dozer or similar piece of equipment. The tractor is flexible for doing lots of jobs, but may not be the best at any one task.

 

[PILOON]

Using your 3-point upper arm, screw in or out helps the cutting action, The more you screw out the more the blade will want to dig, (providing the surface is soft enough).
On compacted gravel however that has little or no effect but adding weight will help.
On my 3-point blade I added a shelf or box affair to add weight.

 

[Dr_Zinj]

Pardon the sloppiness of my quick draw.

You want to be careful about how much you load up extra weight on your scraper. If it's like mine, the two angled supports running from the top link connection to the lift arm connection points are both under compression forces (red arrows). Too much weight and those supports will fail bending like pretzels and you'll be unable to lift the scraper as it will rotate down at the lift arm points. You can have them fail at lower weights if they aren't in good condition, or if they are pulled or pushed bending them slightly out of alignment. (For instance if you carry a lot of logging chain around them - oops!)

Thin, flat stock supports are the weakest. Angle iron stock is better. Solid 3/8 to 1/4 inch steel plate triangles are better yet. And a hollow box construction is probably the strongest per weight, which is how most FEL arms are built.

 

[RDrancher]

Here's how downforce is applied to this float-type scraper--hydraulics

True, but your photo shows a modern skip loader that weighs 14,000 lbs. (with wheel and hitch weights) and is designed for construction work. Downforce is handy, but without the weight it's useless. Even on a skip loader, you can lose traction pretty quick if you're not smooth.