Forward Tilt of a pulling tractor March 11, 2019 04:36AM
I bought a tractor to start pulling with this year in a sanctioned class. Currently there are pretty small tires on the front and this gives the tractor a slight pitch forward. What is the benefit if any, to putting taller front tires on it? Would it put more weight on the back tires and help it hook better? Or would it work against me?
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Re: Forward Tilt of a pulling tractor March 11, 2019 05:20AM
A little tilt forward helps in my opinion I'm sure someone will say different.

Pick up a cinder block from the ground, standing up versus a table. Harder from the ground just like a tractor, harder to lift the front if its low so it transfers more weigh to the rear.

My 2 cents
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Forward Tilt of a pulling tractor March 12, 2019 05:32AM
Not even close to the same thing. Use your cherry picker to pick the cinder block from the ground vs from a table. It's not going to know the difference & you could demonstrate that with a fish scale between the block and the cherry picker.

The most significant advantage is the one mentioned by Hummin Cummins about it being easier to put weights on the rack.
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Re: Forward Tilt of a pulling tractor March 12, 2019 05:39AM
Well its worked well for us whether you agree or disagree. With the tilt we can watch our tractor hook on tracks with tractors of comparable HP cant hook as well. Just saying our tractor loves the tilt.
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Re: Forward Tilt of a pulling tractor March 12, 2019 02:44PM
Quote
Deere Puller
Not even close to the same thing. Use your cherry picker to pick the cinder block from the ground vs from a table. It's not going to know the difference & you could demonstrate that with a fish scale between the block and the cherry picker.


Ok but what's the BACK of the cherry picker hooked to in your scenario?
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Re: Forward Tilt of a pulling tractor March 13, 2019 05:07AM
Back of the cherry picker isn't hooked to anything, what is your butt connected to when picking up the cinder block?

My point was that the cinder block is harder to pick from the ground than the table because when picking from the ground your knees are bent at 90° (if lifting properly, your back more than 90° if lifting improperly). It's the geometry of your body that's changing drastically.

To Fuzz's question below (and possibly yours too), it does technically increase the distance from the fulcrum point, which is the rear axle, but the change is tiny. If the CG of 800# of weights are 5° below the axle, which would be 13-5/8" and the tractor rotates that 5° so that the CG of the weights is even with the axle, your have gained the equivalent of 3# on the front. I'm sorry Overdrawn, but I don't believe that the extra fraction of hitch you might get from that little bit of weight is changing your ability to hook enough to notice. Tires, gearing weight placement, or even driving style are much more likely to be the reason you are hooking better.

The OP mentioned changing the angle of the entire frame by adjusting wheel size. To properly perform that calculation you need to look at the weight of the entire tractor minus rear wheels and tires and know the horizontal and vertical CG location. There obviously is much more weight involved, but the distance from the axle to the CG as well as the angle below the axle achievable is much less. For example, if you were to drop the front axle located 11' forward of the axle by 6", the angle change would be 2.6°, much less than in the above calculation.

If you really want to understand this go back and read this thread and play with the spreadsheet posted Tractor Balance and Hitch loading disucssion
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Re: Forward Tilt of a pulling tractor March 14, 2019 10:19AM
Last year I built the purple peterbilt everything I could possibly think of was built into that chassis. I spent 5 1/2 months building it from scratch. Out of the 5 1/2 months 1 month was standing there looking and figuring out what is best. There is more gains to be made in our class in chassis design and efficiency than any other single thing including horsepower. The one thing that I truly believe in pulling is every single thing we do in building and design matters. The smallest thing is related to larger and bigger parts of the pulling vehicle. All together function as one complete efficient unit. One thing that is my opinion and I will get told why my thought process is incorrect is the use of weight. I think weight should be as far forward as possible or as far rearward as possible. Why would you put 100 lbs in front of the rear tires? My thought is put 25 pounds on the front weight rack and 75 on the rear. The 25 will hold the front down and the 75 goes on the rear to do its job. But the real benefit is to know your vehicle and know how to be the most efficient you can be with everything you do.
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Re: Forward Tilt of a pulling tractor March 11, 2019 01:42PM
I agree 100%. We lower our front bracket a little bit for the very reason overdrawnbimder said.

Plus...It’s easier for the pit man (that’s me haha) that has to throw the weight. But ultimately, it’s all in what YOU like. Because you can still balance that tractor with either set up.
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Re: Forward Tilt of a pulling tractor March 12, 2019 03:16AM
can you say?----- center of gravity?
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Re: Forward Tilt of a pulling tractor March 12, 2019 06:41AM
It increases the distance of travel to the fulcrum point. I'm not a geometry teacher so my wording mite not be exact but you should get the meaning
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Re: Forward Tilt of a pulling tractor March 13, 2019 05:20AM
I didn't mean bending your knees, can your tractor bend in half to pick the front. If your standing without bending your knees pick it off the table vs ground that what i'm saying
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Re: Forward Tilt of a pulling tractor March 13, 2019 06:13AM
This would be a question for Doug Roberts. He had some interesting weight distributions, drawbar angles and other stuff on here maybe a couple years ago. Have no idea how to pull them back up but he understood that kind of stuff.
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Re: Forward Tilt of a pulling tractor March 14, 2019 04:51AM
Put a scale under each front wheel and it won't matter whether the front end is 1 inch above the ground or 3 feet, the weight will measure the same. Any changes the initial height of the front end might have on hitch height and/or bending moment around the rear axle will be negligible.
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Re: Forward Tilt of a pulling tractor March 15, 2019 03:07AM
John you are correct when it comes to showing weight on a scale, but wrong in how it will effect how a tractor responds. It makes a large difference when it comes to how physics works and the effect on a pull. I pull in the TWD class. We run a 30 inch hitch and it makes a huge difference on how high the weight it. It makes a huge difference on how high the motor is out of the chassis because of wight and torque. Every detail matters. But the class you compete in will determine how much effect those items help or hurt. But they all do effect.
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Re: Forward Tilt of a pulling tractor March 14, 2019 07:44AM
What you call forward tilt is known as rake in the chassis world. I am a Rigger and move very large machines every day. I know a little bit about leverage and how it works. By having your front end lower it takes more to pull the nose of your tractor over center which allows the pull down which the sled does by chain angle to be greater on the rear of your tractor. The other benefit to some rake in your chassis is the weight that you would have had to put on the front to hold it down can now go to the rear where you truly need it. I have built a few chassis in recent years but they have been semis but the basic theory is the same. An example if you want to know how rake works and how much easier it is to pick things up when they are level or higher at the front. Is take a forklift and pick something that is maxing it out setting level the rear tires come off the ground easily. Now take the same load and set on a slight incline so the rear of the lift is a little lower. It will pick it right up and the tires will stay on the ground. I have seen more than one guy try to go down a ramp forward instead of backwards. Hope this helps just a little experience I use every day that helps in my hobby. Joe
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Re: Forward Tilt of a pulling tractor March 14, 2019 09:14AM
Joe,- that's what I said,many people are too foolish to know facts and physics,bother present in everyday matters. Many argue about hitch type design and angles,leverage and more,but -- then some win more than others,cuz more matters than just power.
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Re: Forward Tilt of a pulling tractor March 14, 2019 10:34AM
The 10 degree angle of the crank is in the book for a reason. Will they find 15 degrees? Not until you win all the time and someone protest.
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Re: Forward Tilt of a pulling tractor March 15, 2019 03:00AM
What class are you pulling in that has a 10 deg on the crank rule?
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Re: Forward Tilt of a pulling tractor March 14, 2019 11:48PM
It's physics gentleman. I've heard all the arguments over the years concerning chassis design. There are some straight forward facts. You're using the rear axle as a fulcrum point (remember that). You have opposing weight pulling down on your drawbar. The chassis is pivoting on the centerline of the rear axle axis. The lower your center of gravity on the front with weight, makes it more difficult to raise, compared to weight on a level plain. This is why the most successful single engine modifieds usually have the engine almost sitting on the ground in front. Lower center of gravity on the front.The drawbar connection point is another matter of discussion and can effect the ability of the tractor to transfer weight. This is one of the reasons Tim Engler designed the "Engler Hitch".
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