4WD, Planetary or Not

WNYBill · Aug 12, 2017

My Long LandTrac does not have planetary gears in the front end and I have broken 2 axles. None of the "compact" 4WD tractors use planetary gearing. I have said in several posts that I would never buy a 4WD tractor without Planetary front gears. The Kubota folks say they are not necessary and that they never have broken a axle.

My question is: why do the major manufactures, except Kubota, use Planetary gears in their farm tractors if they are not necessary? Isn't the gear system a lot stronger? Exactly what is the difference?

Bill

jm. · Aug 12, 2017

Bill While KUBOTA does not use planetary we do use a reduction gear. The Kubota front end does not have a u joint and allows for CONSTANT power thru all angels of steering. It is a tried and proven set up. In my 28 years selling well over 4 thousand units I can not remember breaking what you call an axel shaft now bearings going out and shelling a drive gear yes happens ever now and then. I can send you a parts drawing if you want to see how it works.

Janicholson · Aug 12, 2017

I will add to what jm is saying. All Front wheel assists need three things to be successful. Ability to turn (the sharper the better). Ability to hold the tractor's power with out damaging stress on its parts. and the ability to match the speed of the travel in a straight line as well as around corners.
Planetary drives allow the drive shafts and joints to be turning faster and thus smaller to conduct the same power.
Non planetary setups use far heavier drive lines and robust joints.
The matching of ground speed is usually pretty good but not perfect for either setup. Some older assists could only use certain tillage gears in use. My opinion is that the best systems do all three tasks well. and poor systems fail miserably. Research the ones you consider and choose wisely. Jim

Ken Macfarlane · Aug 12, 2017

Both types fail when they are undersized. Both fail when they have no oil in them. I've got both types, they both work well in the mainstream brands. Many off brand Japanese, Korean, and Chinese front axles are not designed to take a loader and will break. Kioti used to have a problem with this but has been resolved. Other old compacts used to blow front ends apart too just picking on kioti.

farmer boy · Aug 12, 2017

I'm not 100% sure that Kubota doesn't use a planetary reduction drives in their front axles. I've never had one apart,(I'll let that speak for itself), but looking at the parts diagram for an M6030DT, there is a planetary gear-set in there. Power goes through the bevel gears at high speed, and the bevel gear is also the sun gear for the planet gear set. Sun gear spins carrier, and speed is reduced. So you still get planetary reduction, but without the disadvantages of u-joints. They're not all like that, but a lot of them are.

WNYBill · Aug 13, 2017

JM,

My problem has been metal fatigue. System uses a stub axle, about 10 inches long, flange on one end to attach wheel and a spline gear on the other, bearing in the middle. Part fatigues where the flange attaches to the stub shaft. Dosen't look welded, machined. May be just a South Korean steel problem. Never had a planetary front end apart, but I know all the "farm" tractors (JD, CaseInt,MF,Mahindra, Ford) except Kubota, come with planetary front ends.... or there is a hub sticking 6 inches through the wheel.

Thought the stub axle was a weak link.... but it sounds as if they all are suspect.

I am very careful to only use the front drive when necessary, never leave it in 4WD.

Bill

4WD, Planetary or Not

WNYBill

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jm.

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Janicholson

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Ken Macfarlane

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farmer boy

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WNYBill

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