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you boys helped me with my first issue, i have another one for ya. The differential on a Cub, is there a way to engage it and disengage it? if so how do i engage it? right now i only have one wheel as the drive. thanks in advance.
Nope. Standard differential in the cub. I doubt they make air lockers for cubs!
See the answers below.
Last edited by clodhopper on Thu Jan 10, 2013 11:11 am, edited 1 time in total.
Read the wiki page on differentials. You may want to skip the first section and start with "Purpose".
I think there may be different interpretations of the "only powers one wheel statement". It applies power to both wheels, but the differential allows them to turn at different speeds going around turns, etc. it also allows one to spin if it hits a slick spot, and in that case you use the brake on that side to cause the other wheel to pull. I do not remember where it is, but there was a video recently posted of how a differential works. It was an older Chevrolet video, but the differentials work the same, no matter what it is on.
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Here is the thread from last week with the video John mentioned.
Here are the basic rules:
1. As long as traction for both wheels is equal, both wheels drive the tractor.
2. As soon as one wheel loses traction, that wheel spins and the other wheel stops.
The tractor has two brakes for a reason: When one wheel is spinning, you apply the brake to that wheel so the other wheel will pull.
Im curious why newer tractors with a differential lock have dual brakes.
It helps make turns a bit easier. When one brake is locked the opposing tire will help turn the tractor in the direction of the locked brake.
Yes, that part I understand. I am referring to the earlier statement that the reason tractor have individual rear brakes is because they have standard differentials, so that if a wheel slips, you can brake the slipping wheel to transmit power to the other wheel. In the case of tractors that have a locking differential (many do) why the individual brakes? I am curious because the only thing we ever used brakes for was stopping and turning.
Edit- The cub is the only tractor I have used that DOES NOT have a mechanical differential lock. That is the root of my curiosity.
I like differential locks, and it's slightly disappointing the Cub doesn't have one. But even on a modern tractor, I use the individual brakes much more often. A differential lock can get you out in a pinch, but for me side brakes are much more useful day-to-day.
Making a sharp turn, like at the end of a crop row, put on one side brake and the tractor virtually pivots around the braked wheel, since it doesn't move at all. Also for hitching implements, it's useful sometimes to tweak the angle of the tractor toward the braked wheel, without that side of the tractor moving backwards.
Turning in wet ground, or even loose soil at any reasonable speed, the front wheels don't grab the ground and turn the tractor and instead the face of the front wheel just pushes the soil forwards and the tractor keeps going straight. Side brakes slow one rear wheel, and so the tractor turns in line with where the front wheels are pointing.
Similarly -- and I think of this as more of an Oh #*^$% moment -- when pulling a soil-working implement with lots of resistance, the front of the tractor can raise off the ground or at least have enough weight off the ground that turning the front wheels doesn't do much. Side brakes here are the only way to keep the tractor going in a straight line.
Diff locks didn't become commonplace until the last 20 or so years on the smaller tractors. My neighbor's 231 Massey is the only one I've run with a locker and I personally don't like them - when you get to the end of a row and forget you have it locked, you have to straighten back out to get it to unlock.
This discussion also reminds me of a long ago argument about 4 wheel drive.....is it really 4wd if it doesn't have a locking center and limited slip front and rear?
The guys that spent the extra money on the diffs will tell you that theirs is the only one with true 4wd.
On anything with an open differential, the torque is transmitted equally to both sides - when one side has near zero and the other has lots of traction, the side with no traction gets all the speed. At that point the torque transmitted drops to the lower of the 2 traction numbers.
There are still instances where it's preferable to control which wheel receives power using the brakes rather than let both wheels dig holes to China.
My Dad uses the feature to backfill holes left by large stones in fields after he digs them out with the loader. The loader is full of rocks you can't use it to scoop up some dirt and dump it in the hole, and it's too much time, fuel, and trouble to come back later. Sometimes there is no loader. So, he backs up one wheel to the hole and spins some dirt in it by holding the other brake.
Kind of like a giant mechanized cat covering up its business in the great litter box we call life.
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