What is the phenomenon called...

[Mowbizz]

When you are going up or down hill with a heavy load and the tractor starts rolling backwards (in the case of uphill) or rolls forward in the case of downhill?
Seems like being in 4wd eliminates this.
Brake pedal seems to be ineffective as well when this happens...definitely causes a pucker factor too!

 

[marchanna]

Gravity.

 

[thatguy]

yes.. big issue going down.. brakes are on the rear wheels.. 4x4 will help stop you if this happens

brian

 

[Mowbizz]

So gravity overides the HST?

 

[Mowbizz]

But what exactly is happening mechanically?

 

[mljenkins]

You are free wheeling. Your rear tires are losing traction or in worse case completely leaving the ground. Without 4wd most tractors do not have front braking. Hence your front wheels just roll freely while the rears are essentially sliding. This is caused by the weight shift going downhill (or backwards uphill) with a heavy load on the front but not enough load on the rear to keep the rear wheels firmly on the ground. Hence no amount of braking, downshifting, or hst control will help when this condition occurs if you do not have 4wd engaged.

 

[Peter 315]

When you are going up or down hill with a heavy load and the tractor starts rolling backwards (in the case of uphill) or rolls forward in the case of downhill?
Seems like being in 4wd eliminates this.
Brake pedal seems to be ineffective as well when this happens...definitely causes a pucker factor too!

You might need these if its a big hill

 

[LittleBill21]

your simply losing traction, if you have the balls for it, stepping on the gas and accelerating will sometimes get your traction back, since the wheels have caught back up to the speed your slipping.

 

[Luke'sScreenName]

If I understand correctly...
You need to be in 4wd AND you need rear ballast (big time my friend). That is indeed a potentially dangerous situation.

Ought to be more likely going down hill. Weight pivots on the front tires and the rear tires lift to the point of loosing traction. That means no HST breaking or mechanical breakings. So you just drop the bucket into the ground, prey, and wash your underwear...

 

[k0ua]

So gravity overides the HST?

No, that is not what happens. In fact the Hydrostat acts as a brake, but when you are in 2wd, the only contact patch that braking can be applied to the ground is the rear tires. What happens is that the contact patch breaks traction with the ground and the tractor slides down hill, picking up speed. When you are in 4wd, you can also utilize the contact patch of the front tires with the ground. This helps prevent the sliding tires down the hill.