Hills: Forwards or Backwards?

[Kelvin]

To all,
I first admit that I don't know what the real answer is, but I was under the impression the AG tires give more traction in reverse and that the design allowed the tire to shed built up dirt accumulations better while moving forward.
Kelvin

 

[gerard]

glenmac,
In your scenario 2 I would agree with you. If back heavy (maybe rear implement on, no loader) I would prefer to back up a hill, no doubt. My position was for the 50/50 weight distribution. In that case there's no particular advantage to EITHER direction until you consider the factor of tire size and traction direction. Taking these into account going up forwards would put more traction on the larger (rear) drive wheels AND allow the tires (If R1's) to roll in the direction they have the greater traction. (This applies to R1 bar type tires. It's not even close. Forwards has substantially greater traction than reverse. I can pull things forward with no problem that I can't pull backwards without the wheels spinning)

 

[glennmac]

Gerard, in the balanced situation we agree that the flip risk is unaffected by tractor direction. Therefore, the risk is a break in traction that results in a side slip. Your argument for rear wheel downhill has three components: (1) the traction-affecting directionality of the tread, (2) the greater size of the downhill rear wheel, and (3) the weight that is shifted onto the downhill wheel. Let's look at each component separately.

You are on the steep snowy hill going up to the Carrier Dome. Your car is evenly weitht balanced, has all the tires the same size with non-directional tread. Your car has fwd, rwd and 4wd. To avoid sideslipping traction risks do you go up the hill in fwd or rwd. I say fwd. If traction breaks on the front drive wheels there may be some back slipping and side jigglling, but the traction will probably catch again and the front-driving wheels will pull you back up on a straight course. If you are in rwd and traction breaks on the rear wheels, you will never recover onto a straight course even if the rear wheels catch again. I think this argument holds true, even though more weight is on the downhill axle than the uphill axle. Thus I do not agree that your weitht shift component for traction-saving is valid.

What about the tread component. Well, so far we have differnt views on whether ags have more traction going forward. (I'm not saying your wrong). But if we were on turfs, you would have to concede this component, too. And even if ags have more traction going forward, how much is the differential? Does it outweith the uphill pulling benefit? What about R4's.

Your third component argument would assume you car was now outfitted with larger tires on the rear (nodirectional and evenly balanced). Do you go up in rwd over fwd? Maybe the chance of breaking traction on the larger wheel is less than on the smaller wheel, but even if so, once it breaks on the rear wheel, you will not recover and are a goner. Plus, I'm not sure that there would be any traction differece if all the tires are filled with snow or mud. Wouldnt it be better to go up the hill backwards in four wheel drive. Your big diameter wheels will be pulling up hill and your front wheels, albeit smaller, will also be driving with a weight shipt on them.

I think your arguments have force, but I still dont think the combined effects outweith the clear anti-side sliding value of driving backwards uphill in 4wd.

By the way, if you are right and we should go up frontwards, do we agree that you should have rear wheel differential lock on to minimize side slip?

 

[gerard]

I definitely agree about having the diff lock on and using 4wd, no argument there. In a 50/50 weight example I just don't see that there's really that much advantage either way, but then I'm basing this only on practical "seat of the pants" experience. Ive done it in both directions and have not felt one superior over the other. Trying to compare the tractor situation to a car is a little apples and oranges. Tractor tires turn slowly and don't have the same impact when slipping that a car would have. You also have the different size tire factor in a tractor that you don't have in a car. With regards to R4's tires the traction is similar to that of an R1. (unidirectional) but not as drastic, at least not on the R4's I've seen. Using your scenario of turfs, I could agree that going up the hill backwards might be safer than frontwards, especially in a "pop the clutch" situation. Going forwards I could see the front end coming up or at least getting light. If you were in reverse backing up the hill this would not happen. (See you're logic is overwhelming me but then you keep taking away the conditions on which I based my conclusions!

 

[glennmac]

Another factor to add to the mix in the evenly balanced situation.

If I'm backing up the hill and traction does break, I am now going forward (more or less)and I have familiar options: steering, braking, clutching. If I am going forward up the hill, traction breaks and I start going downhill backwards or sideways, I'm really in unfamiliar panicky territory. In other word, I'm in a more comfortable recovery situation if I'm backing up when the worst happens....Glenn

 

[gordon]

I'm with you Bird, keep it simple down forward and up backwards. Sure does take the fun out of the thread though.

Not only using four wheel drive on a steep hill but different types of tires and tire pressure can add so many different combinations alone to the hill subject without even taking into consideration of the heavy front end and so on.
Gordon

 

[glennmac]

Gordon,

I'm in favor of simple safety rules if they are correct.

Let me ask you the same simple question I ask of Bird: If you have a very heavy bucket and no ballast on the back, are you going to go up a steep slope backward?

Glenn

 

[Bird]

Glenn, I don't know about Gordon, but a very heavy bucket and no ballast on the back? I don't intend to do that in the first place, and in the second place if I did, yes, I'd go up backwards with the bucket practically dragging the ground, and if I cain't get there that-a-way, I ain't goin'./w3tcompact/icons/laugh.gif

Bird

 

[glennmac]

Bird, that's a reasonable response. Agreed, none of are going to put ourselves in these hypothetical situations that I am posing. But I am trying to flush out a real safety rule by continuing to box people in.

I will continue with my hypothetical.

You MUST go up the mountain, and the Grand Canyon is at the base of the slope if you slip down. You had taken all the ballast off your tractor except your bucket because you were repairing things. Just then, you are asked to take 750 lbs of radium to the hospital on the top of the mountain to some cancer patients who critically need it. Your bucket barely lifts it. Your tractor is level on the level ground but you know you are extrmely front heavy. You are committed to save the patients.

The slope is steep and you suspect it gets even steeper a quarter mile up. You start up backwards. As your rear rises up the slope the COGV shifts even closer to the front axle. You take comfort in knowing that even if you pitch over the downhill front wheel your lowered bucket will keep you from pitching over. It happens. The slope steepens and you are balanced on your front wheels and the bucket one quarter mile above the Grand Canyon. What are you going to do now?

Suppose you had gone up frontward. There are two things I think you know for certain. First, you will never pitch over backward (downhill) because of your super heavy front bucket. But you also know that you cannot pitch forward into the hill. Why? Because you did not pitch forward on level ground. That means the steeper it gets, the LESS likely it is that you can pitch forward and go out of control. Therefore, by going up forward you eliminate BOTH the possibility of pitching forward or backward.

You save the patients. No?

Glenn

 

[gordon]

Once again I'm with Bird---up a hill and no rear ballast of any kind---I might be alittle crazy but I'm not stupid! Ballast is key to safe operation not only on hills but on flatland as well. I've got weighted tires liquid in the rear and when using the loader I usually have the boxblade or gradeblade on the back as well. The steadier the tractor the more work you can get done with it. Don't have to worry about lifting a wheel or being light in the rear.

Now to address your last post Glenn---If I was working on my tractor in my yard I've got enough heavy steel that I could put on for ballast to hang on the rear in a five minute time frame without using the three-point hitch. Lets say for a hypothetical situation that I was working on the three point and it was out of action.

So in essence I would make it up the second part of the hill not only safer but could do it faster because I have ag tires and they grip better going up the steeper part of the hill.---Did I save the patients and do it in a safe manner so I will be able to see the sunrise tomorrow---YES

There is one thing that you have to always take into a hypothetical situation---handlin yes thats it handlin. You see Glenn I have been to handlin school and I sure can handle the quest that has been put to me. One other thing alot of hours in the seat of a tractor thats something that you can't take away---plain old experience that will always help to get you through the tough times./w3tcompact/icons/smile.gif

Just remember that going up a steep hill with no rear ballast and a loaded bucket you might not flip over but you will be spinning some rear tires so you better be sure to have that tractor in four wheel drive before you start the hill. So at least the front wheels on your tractor would be gripping the ground between you and the Grand Canyon./w3tcompact/icons/smile.gif

Gordon