Jubilee Cut Away Running

[Tom Bond]

Not sure if this has been posted before but pretty neat anyway.

http://youtu.be/5kNHnYdi6Q0

 

[Sean in PA]

It's neat, but it ain't right. With no wheels on it, the two brake drums should be turning in opposite directions, and both of those are turning in the same (forward) direction, so they did something to lock the differential.

 

[Mark Slater]

Nice cut-a-way.

I know the wheels should turn opposite directions when you have it up on jacks, tranny in neutral, turn from one wheel then watch the other.

I thought powering the wheels with a motor from the tranny input, whether on or off the ground, should have the wheels turning same direction as each other. What would the difference be from powering the tranny with an engine in forward gear and the setup shown in the video? Is just lifting the wheels off the ground enough to make one spin backwards? Is there a diff lock on the Jubilee?

Still learning this stuff.
- Mark

 

[JMOR]

(quoted from post at 11:11:39 08/26/14)
Nice cut-a-way.

I know the wheels should turn opposite directions when you have it up on jacks, tranny in neutral, turn from one wheel then watch the other.

I thought powering the wheels with a motor from the tranny input, whether on or off the ground, should have the wheels turning same direction as each other. What would the difference be from powering the tranny with an engine in forward gear and the setup shown in the video? Is just lifting the wheels off the ground enough to make one spin backwards? Is there a diff lock on the Jubilee?

Still learning this stuff.
- Mark

lad to see someone else is paying attention. Sean's comment so I'll let him field it.

 

[Sean in PA]

Let's see how I do. This is how I understand it:

Normal differential operation when receiving powered input is to only supply power to one wheel, the one that has the least resistance, like the one on the outside of a turn, or the one that is slipping on snow or ice or mud.

When the wheel with the least resistance has traction, like the one on the outside during a turn, the other wheel follows along because the external friction of that tire on the ground makes it spin along with the direction of travel, but only one wheel is actually receiving power from the ring and pinion gears.

Normally, if one wheel loses traction with the ground, like when it's on ice or mud, that becomes the one with least resistance and that wheel receives the input power from the ring and pinion and it spins, and since it is not propelling the tractor forward, the other wheel stays still and does not rotate at all, again because of its external friction with the ground.

In the special case of both wheels losing traction with the ground at the same time, like when the rear end is on jack stands like in that video, one wheel (hub) will still have slightly less resistance than the other due to slight variances in bearing tolerances, the amount of lubrication available etc. and that wheel (hub) with the least resistance will spin in the direction that the input power is turning the ring gear in the differential, while the other wheel (hub) will either not spin at all, or will spin slightly in the opposite direction just like they do when you have the rear end jacked up and you spin one wheel by hand when no power is being applied.

 

[Dan Robertson]

Oh my--- must be something wrong with this JD running on 4 coke bottles. I see both rear wheels turning the same direction. Probably ten or more of these on You tube all with wheels turning the same direction. Dan

 

[Dan Robertson]

Forgot the link.
http://youtu.be/5TCZBVRtLQ4

 

[Mark Slater]

(quoted from post at 17:54:44 08/26/14) Let's see how I do. This is how I understand it:

Normal differential operation when receiving powered input is to only supply power to one wheel, the one that has the least resistance, like the one on the outside of a turn, or the one that is slipping on snow or ice or mud.

When the wheel with the least resistance has traction, like the one on the outside during a turn, the other wheel follows along because the external friction of that tire on the ground makes it spin along with the direction of travel, but only one wheel is actually receiving power from the ring and pinion gears.

Normally, if one wheel loses traction with the ground, like when it's on ice or mud, that becomes the one with least resistance and that wheel receives the input power from the ring and pinion and it spins, and since it is not propelling the tractor forward, the other wheel stays still and does not rotate at all, again because of its external friction with the ground.

In the special case of both wheels losing traction with the ground at the same time, like when the rear end is on jack stands like in that video, one wheel (hub) will still have slightly less resistance than the other due to slight variances in bearing tolerances, the amount of lubrication available etc. and that wheel (hub) with the least resistance will spin in the direction that the input power is turning the ring gear in the differential, while the other wheel (hub) will either not spin at all, or will spin slightly in the opposite direction just like they do when you have the rear end jacked up and you spin one wheel by hand when no power is being applied.

Thanks for the explanation Sean.

I found a few other videos that had tractors on jacks spinning wheels. They mostly were showing the same motion as this one did. Both wheel same direction about the same speed.

I did find one that showed one wheel much faster than the other. https://www.youtube.com/watch?v=9qWzSCHjuWM But still both in the same direct... get the wheels to move like that. - Mark

 

[JMOR]

(quoted from post at 14:41:48 08/26/14)

(quoted from post at 17:54:44 08/26/14) Let's see how I do. This is how I understand it:

Normal differential operation when receiving powered input is to only supply power to one wheel, the one that has the least resistance, like the one on the outside of a turn, or the one that is slipping on snow or ice or mud.

When the wheel with the least resistance has traction, like the one on the outside during a turn, the other wheel follows along because the external friction of that tire on the ground makes it spin along with the direction of travel, but only one wheel is actually receiving power from the ring and pinion gears.

Normally, if one wheel loses traction with the ground, like when it's on ice or mud, that becomes the one with least resistance and that wheel receives the input power from the ring and pinion and it spins, and since it is not propelling the tractor forward, the other wheel stays still and does not rotate at all, again because of its external friction with the ground.

In the special case of both wheels losing traction with the ground at the same time, like when the rear end is on jack stands like in that video, one wheel (hub) will still have slightly less resistance than the other due to slight variances in bearing tolerances, the amount of lubrication available etc. and that wheel (hub) with the least resistance will spin in the direction that the input power is turning the ring gear in the differential, while the other wheel (hub) will either not spin at all, or will spin slightly in the opposite direction just like they do when you have the rear end jacked up and you spin one wheel by hand when no power is being applied.

Thanks for the explanation Sean.

I found a few other videos that had tractors on jacks spinning wheels. They mostly were showing the same motion as this one did. Both wheel same direction about the same speed.

I did find one that showed one wheel much faster than the other. https://www.youtube.com/watch?v=9qWzSCHjuWM But still both in the same direct... get the wheels to move like that. - Mark

o tricks, just differential action. In your JD video, one wheel is going as much faster than the other as the other is slower, relative to both running the same speed. Stop one entirely, by force of your hand, and the other will be turning twice as fast as if both were turning together at same speed. It is a "differential". If driving down the road, perfectly straight, absolutely same tire circumferences, same friction, etc. then both wheels are turning same speed & both applying equal torque to moving vehicle forward.

 

[Mark Slater]

Thanks for the info JMOR.
That makes sense to me.

Does anyone know:
- Is an older tractor differential much different than a car differential?
- Were there ever tractors made without differentials?

I know there are a few different types of automotive/truck differentials. Open, LSD, Breaking/LSD, & Locking. My experience in diffs is limited to replacement only. You put in the same as you take out unless you really know what your doing.

- Do newer tractors have more sophisticated diffs?

Thanks again, I'm soaking it all in.

- Mark

 

[JMOR]

(quoted from post at 16:16:52 08/26/14)
Thanks for the info JMOR.
That makes sense to me.

Does anyone know:
- Is an older tractor differential much different than a car differential?
- Were there ever tractors made without differentials?

I know there are a few different types of automotive/truck differentials. Open, LSD, Breaking/LSD, & Locking. My experience in diffs is limited to replacement only. You put in the same as you take out unless you really know what your doing.

- Do newer tractors have more sophisticated diffs?

Thanks again, I'm soaking it all in.

- Mark

any have a locking capability.