tractor math

I did some figuring the other day. The 9150 on the grain cart is kinda light up front when the cart's loaded. The drawbar pin to the the rear axle is about 4'2". It's about 18 1/2 feet from rear axle to the nose of the tractor. If we were to hang some suitcase weights about a foot and a half in front of the nose of the tractor, 20 feet from the axle, that would affect the balance of the tractor 5 times as much as the same amount of weight on the drawbar, right? So 1,000 pounds of suitcase weights would be like removing about 5,000 pounds off the drawbar, as far as balance goes?

Yes, I know, the weight will still be on the drawbar, I'm talking balance and weight bias, not actual drawbar load.

The book says to add fluid in the tires for ballast, but there's mounts for fertilizer tanks up front that carry 5500 pounds of liquid fertilizer (plus tanks and pump). They should carry a ton of weight easily, and the weight should be more effective farther forward.

Or am I thinking about this all wrong?

The front end weight are a better solution than fluid in the tires. Less compaction and better traction and ride.

As far as balance, yes. But in pulling you also have torque to figure in. the extra traction of the rear wheels tend to transfer weight from the front. How much, I have no idea.

Tractor Math, lever problem, torque problem, 9th grade general science, all the same.

Think of your rear tires as the fulcrum. You have 5000# on one side of a first class lever and 4'2" from fulcrum. For 1000# to balance the lever it has to be 5 times the distance from fulcrum, 5 x 4'2" = 20'10".

So yes you are thinking right. You would have to have big front tires to put 1000# ballast in them and then remove it when you put a tank in front. Go with weights, extend them as far in front or rear axle as possible.

Is the fertilizer tank/s on the front or sides of the front--I've seen them both ways. Anyway why not just fill it with enough water to add the weight needed? Easy to drain out later. Or is that contraption going to be in the way and you've taken it off?

Anyway, your math is right but I doubt you need to offset the entire tongue weight. If it's moving it now but the front is light or comes up only as you start to move, a couple hundred pounds will probably be enough.

We had a similar problem a few years ago when we rented a 500 cubic for spreader to pull behind our Oliver 1855. It has a bunch of weights up front but the wheels were still a bit light with a full load. Probably could've used 1 more slab weight. Sure got the job done though. For every one load I hauled with that, it was like 2 loads with our spreader that dad was using.

Donovan from Wisconsin

Statics is the science you are looking for. Dynamics is the science to use if you want to include how wheel torque, drawbar pull, momentum, changing inclines, acceleration, turning, etc. all have an affect while moving.

For adding front end weight ahead of the front axle, as long as the front axle stays on the ground use the front axle as your pivot (balance)point.

Adding 1000 pounds of fluid in the front tires (centered at the front axle) would add 1000 pounds to the front axle and would not have any effect on the rear axle or drawbar.

Adding 1000 pounds ahead of the front axle would add 1000 pounds to the front axle plus transfer some weight off the rear. For example: if the extra 1000 pounds is centered 3 feet ahead of the front axle and the rear axle is 12 feet behind the front axle, you would transfer 1000lbs x (3feet/12feet) = 250 pounds from the rear axle to the front axle. The front axle carries 1250 pounds more and the rear axle carries 250 pounds less.

You probably don't want to leave the extra ballast on the front of the tractor when you carry a heavy fertilizer tank on the front of the tractor every spring. If you already have the suitcase weights, they would be handier than adding and removing fluid from the front tires every year.

If you don't have the suitcase weights, then buying them at $1 per pound would cost $1000. A rock box would be a low cost way to safely carry an extra 1000 pounds of inexpensive ballast, rocks, scrap iron, gravel, etc.

Good luck.

The book only deals with unloaded static weight. Says that with a high vertical draw bar load like with pans (or 1100 bushel carts) to ballast it to 65percent front axle weight but it's got the heavy axles, 3 pt and pto so that isn't possible without getting the operating weight too heavy. That without front ballast the rear drive components do too much of the work and wear out faster. And it doesn't pull the cart much better than the 7250 uphill.
The tanks are 2 rows wider than the duals. I thought of that. I have just enough room as it is to turn around in 24 rows without the extra width up front. Building a bracket to hook to the tank mounts on the tractor would be easy enough and there's 2 sets of suitcase weights in the back of the shed. With the forklift we could pull 4 bolts and not even need to remove the weights from the bracket.-
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