4wd and 4 wheel brakes

roger_scotty · May 31, 2002

There are a few moments on a person's life that he will always remember. Emotions so powerful that every detail of memory is perfect...

One of these events that is known only to tractor people usually happens the first time that we load up the loader bucket and innocently start down a hill in low gear. Somewhere on that hill the soon-to-be-wiser tractor driver is going to step on the rear brakes and then aawwaaaay we go!

I guess all of us have been there. Its something a prudent person only does once.
And after looking over the situation, it is easy enough to see that the wild slide was a matter of the weight shift lifting the rear tires plus all the changes in tire-to-ground friction that happens when the tires "unload". This is one time when having 4wd engaged is a double benefit. Not only do we have more tires to spread the engine forces around, engaging 4wd also helps with the braking.

EFC · May 31, 2002

Good post Roger!

roger_scotty · Jun 1, 2002

Thanks, EFC. I started the thread hoping that it would inspire someone to post a good tech explanation of why engaging 4wd also gives you 4 wheel brakes. It isn't obvious till one thinks it through. But while trying to make the intro sound readable I kinda lost the handle on the thing....Nice of you to work through it.

nuvz · Jun 1, 2002

of course, Roger is right apout the "thrill" associated with the loss of traction. That is one of the major reasons I switched to a 4X4 tractor. Driving into a ditch nose first just one time with 2 wheel drive will force you to go get the pickup & a chain. Those front wheels pushing make up for a boat load of bad judgement....

EFC · Jun 1, 2002

Roger that thread hit home. More than a few times it happened to me when I was a kid. But the most memorable moment was my mom driving a 2640 JD pulling a 4 wheel hay wagon. Our ranch is mostly farmland but very steep and hilly. My dad was very attentive to the notion of farming straight up the steep hills only and finding a smoother way down. My mom was headed to the barn with a full 5 ton of alfalfa one day and just figured since she drove up the hill why not just go down the way she came. My dad was on the back of the trailer and I was walking behind. I will never forget the look on my dads eyes when they started to speed up. did I forget to mention the tractor had a very big JD front end loader on it. It tended to run a bit front end heavy. That particular hill runs for a good half mile before it starts to taper down a bit. There were two perfect marks in the ground where the tires were sliding. My dad made it to the tractor (don’t know how….they were flying!) and kept it straight. Using 2wd tractors on hilly ground is fine but it requires a more experienced tractor operator and you have to pay attention. My mom is still convinced that we were trying to kill her. We explained to her that you never kill off free labor, hehe