Hill Climbing Primer

[SPYDERLK]

I may be misunderstanding your example, in which case I apologize, but I don't think this is correct. >>If you are pulling from below the axle, then the torque will tend to rotate the front end downwards into the ground. If you are pulling from dead-center on the axle, there will be no torque.<< And if you are pulling from above the axle, the torque will tend to rotate the front end upwards.

I think what you are saying is that the lift arms attach above the axle, so if you are pulling from the lift arms, there will always be torque to raise the front end--but to me that seems like an argument for pulling from the drawbar, not the lift arms.

No. Any pull point above the ground [where the tractor applies force] has backtip potential --- increasing with H.
larry

 

[Gordon Gould]

You are pulling from the H of the ball ends if the hydraulics is holding them above the attachment point of the arms on the tractor for the reason I said earlier. If the ball ends are, instead, lo you are pulling from the arm attach point on the tractor, and since that point will not move downward as the tractor tips the tip does not self damp. The operator has less recovery margin. BabyGrands method has all the advantages you cite as well as the added safety of a drawbar pull.
larry

I think we are saying the same thing. I am saying the force to pull and lift the log can be devided into two components. One horizontal (the pulling force) at the lift arm attachment point to the tractor and one vertical (the weight) at the lift arm ball end. Those two forces can be combined mathamatically into one force which would be above the lift arm tractor point. Your force.

If the log is raised off the ground, supported by the liftarms, and the tractor rolls back so the log suddenly rests on the ground the whole force picture has to change because the vertical weight component of force on the tractor suddenly dissappears. The front end gets heavier. I don't think you can remove a force and have nothing happen.
Oh well that is the way I see it anyway.

 

[SPYDERLK]

I think we are saying the same thing. I am saying the force to pull and lift the log can be devided into two components. One horizontal (the pulling force) at the lift arm attachment point to the tractor and one vertical (the weight) at the lift arm ball end. Those two forces can be combined mathamatically into one force which would be above the lift arm tractor point. Your force.

If the log is raised off the ground, supported by the liftarms, and the tractor rolls back so the log suddenly rests on the ground the whole force picture has to change because the vertical weight component of force on the tractor suddenly dissappears. The front end gets heavier. I don't think you can remove a force and have nothing happen.
Oh well that is the way I see it anyway.

Please read my prior post. #31, I believe. The site works so poorly that you cant multi quote - among other features that cant be relied on.

The pull point is not the attachment point of the arms on the tractor. Instead, when the ball ends are held above the attach point the effective pullpoint is at the height of the ball ends. Otherwise you are right. Take a look at the link post 35 with BabyGrands attach method and note the difference in how the forces resolve.
larry

 

[oercheron]

For the logs that will be firewood, I would cut into firewood at the landing and carry buckets of firewood up the hill. This will also give you a chance to "find the limits" of your machine.

For the rest, you may not need a winch. If you can pull in a straight line from the top of the hill, just use a long cable and snatch block if you need it. From the pics it looks possible, have to be there and see it to know though.

I think you will need to experiment quite a lot with different techniques to get this to work, your tractor is on the small side to get this done. But it is certainly possible and probably doable.

Carrying long heavy logs crossways uphill with a small tractor... well I just wouldn't try that. Too many ways to get in trouble. Pull 'em - snatch block, double snatch block, winch, whatever it takes. This is going to be slow work whichever way you do it, might as well avoid the rodeos!

Good luck!

 

[joshuabardwell]

No. Any pull point above the ground [where the tractor applies force] has backtip potential --- increasing with H.

I don't think this is right. I have pulled on a stump with my drawbar, and my tractor ground to a halt (wheels spinning), but the front end didn't come up at all.

Just for fun, I made this:

 

[SPYDERLK]

I don't think this is right. I have pulled on a stump with my drawbar, and my tractor ground to a halt (wheels spinning), but the front end didn't come up at all.

Just for fun, I made this:

Couldnt watch it. Says private. I suspect you just dont have enuf rear traction to lift the front using a lever the H of your drawbar. A FEL often prevents that due to its front weight bias..

 

[joshuabardwell]

Couldnt watch it. Says private. I suspect you just dont have enuf rear traction to lift the front using a lever the H of your drawbar. A FEL often prevents that due to its front weight bias..

Sorry--I got the settings wrong. It's public now. The traction issue may be true for my full-size tractor, but for the little model tractor in my video, traction is basically infinite relative to the weight of the front end.

 

[CalG]

I suggest that the OP take three trips up and down the land with only the tractor and no load. If the travel is made without concern, on the fourth trip, add a small log and see how it goes.

Weight on the loader takes weight off the rear wheels. Might just spin to a halt.

A logging winch seems like such a good investment.......

 

[davrow]

The site works so poorly that you cant multi quote - among other features that cant be relied on.

Sorry--I got the settings wrong. It's public now. The traction issue may be true for my full-size tractor, but for the little model tractor in my video, traction is basically infinite relative to the weight of the front end.

Hmm, I seem to be able to multi quote...

 

[SPYDERLK]

Sorry--I got the settings wrong. It's public now. The traction issue may be true for my full-size tractor, but for the little model tractor in my video, traction is basically infinite relative to the weight of the front end.

The axle has to apply the torque. You are essentially pushing the model at the H of its axle. In the normal situation the wheel does push the axle, but by tractor based torque acting thru a lever that is the wheels radius, and pushing backward on the earth. Tip takes place at the tire to earth interface. Resistance to the tractors motion at any point above earth applies a backtip torque thru a lever as long as the height of that point. Enuf traction and a tractor will tip at any lever length greater than zero. During backtip a fixed drawbar of decent length moves enuf earthward quickly, thereby shortening the lever quickly enuf to exceed traction and arrest the tip in most cases.
larry