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

[Bstarn]

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

 

[TripleR]

Weight of the implement and lift arms etc., 3PH is floating, no down pressure.

These might help since you are new to tractors: "How To" Operate and Drive a Tractor: Part 1 - YouTube

How to Drive-Kubota MX5100 - YouTube

 

[bcp]

I am trying to figure out how down pressure is maintained on the scraper.
GRAVITY

Is it the weight of the tractor through the 3 pnt hitch,
NO

or is it simply the weight of the scrapper itself?
YES

Does a heavier tractor or ballast in my tires allow me to cut deeper into the roadbed?
YES, YOU WILL HAVE MORE TRACTION, SO YOU CAN PULL MORE OR CUT DEEPER.

Bruce

PS Welcome to TBN

 

[lostcreekranch]

Down force is strictly from weight of the scraper. A heavier scraper, box blade, etc. is going to give to possibility of deeper cut. You can usually add some weight to implement but won't be significant.

Rick

 

[mguitas]

:welcome:to the tractorbynet.

 

[jeff9366]

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.

Implement weight transfers to the rear wheels through the two Lower Links. Implement weight transfers to the front wheels through the Top Link. Weight transfer is from the mounted implement to the tractor.

The next incremental improvement in traction comes with four wheel drive.

 

[rockinmywaypa]

You may notice that a good scraper will be curved, the reason is that the leading edge will pull itself down as it moves forward same as a plow point but to a lesser extent. This helps it dig into the ground instead of floating up and over every bump.

 

[bcp]

Implement weight transfers to the rear wheels through the two Lower Links. Implement weight transfers to the front wheels through the Top Link. Weight transfer is from the mounted implement to the tractor.

Thinking about that makes my brain hurt.

This is how I understand the linkage:

When the tractor is carrying the implement, the weight is transferred to the rear wheels by the lower links in compression, but the top link is in tension, and would lighten the front end.

When the implement is on/in the ground, the ground holds the weight. The lower links below the axle are in tension caused by traction and implement resistance. The top link above the axle is in compression, since the implement would rotate forward otherwise. These forces, not the implement weight, add down pressure to the tractor.

Bruce

 

[smstonypoint]

Thinking about that makes my brain hurt.

This is how I understand the linkage:

When the tractor is carrying the implement, the weight is transferred to the rear wheels by the lower links in compression, but the top link is in tension, and would lighten the front end.

When the implement is on/in the ground, the ground holds the weight. The lower links below the axle are in tension caused by traction and implement resistance. The top link above the axle is in compression, since the implement would rotate forward otherwise. These forces, not the implement weight, add down pressure to the tractor.

Bruce

Me too as far as a headache -- mine is Excedrin Headache #53.

A couple of issues in this thread have me confused.

1. Do the physics change when considering ground-engaging equipment (e.g. a blade) versus a rotary cutter? Some use a chain rather than a top link when using a rotary mower and a chain can't be in compression.

2. Some early lift systems were two-point. How did those systems avoid forward rotation?

Steve

 

[bcp]

1. I think that the cutter is behaving like a trailer when the chain is slack and like a carried implement when it is not.

2. They had rigid connection points instead of pins that could pivot.

Bruce