4tillingdirt
Silver Member
I have noticed that some tractors mention they have a planetary final drive instead of a bull/spur final drive or any other design I have not mentioned. Is this just marketing hype?
Different types of rear ends on compact tractors
- Thread starter 4tillingdirt
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mddorange
Elite Member
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- 2014 Kubota L3200 DT w/LA524 FEL, Loaded rear tires, LP RCR 1860 5' Cutter, LP RTA 1258 5' Tiller, LP PFL 2042 Pallet Forks w/60" Extensions, KK BB60 Box Blade, KK PHD-12" Post Hole Digger
Cat puts planetary gears in there tractors so they must work hard and last longer.
Agvg
Elite Member
One reason to use planetary gear are that they are very compact and in and outgoing axle are on the same level and in center. But for the end user I can't see any reason to wonder about what solution the factory did choose.
sd455dan
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- Rhino 554, Ford 550 TLB (JD X500, MTD, Gilson riding mowers) Ford 3000-Sold
The planetary sets should be stronger- because instead of 1 gear pair contact area there are usually 3 or more, this should increase the torque capacity and reduce the load on each tooth of the mated gears.
As an example most 4x4 tractors above around 50 HP switch to planetary gear (outer) front axles.
As far as rear axles go I would take a 4 pinion 3rd member over having a planetary reduction versus spur gear reduction in the final drive, Seems there are more failures posted on TBN due to failures of 2 pinion differentials than rear axle spur gear failures. jmo and :2cents:
IchabodCrayne
Bronze Member
There are strengths and weaknesses associated with different designs. As an owner/operator it is beneficial knowledge that can help you use your equipment in a way that avoids the weaknesses making equipment last longer.
ie: helical cut ring and pinion gears are thought to be quieter and more efficient but weaker in reverse than straight cut. Straight cut do not have a weaker direction but are louder, can have more lash and generate more force laterally (gears trying to push away from each other) which may need heavier case/housing.
(please note I'm not an expert. I'm simply illustrating the value of knowing what you're running)
ie: helical cut ring and pinion gears are thought to be quieter and more efficient but weaker in reverse than straight cut. Straight cut do not have a weaker direction but are louder, can have more lash and generate more force laterally (gears trying to push away from each other) which may need heavier case/housing.
(please note I'm not an expert. I'm simply illustrating the value of knowing what you're running)
Agvg
Elite Member
Very rare to have rear axle reduction gears failure, if that are a concern under normal use then the equipment must be considered pure junk. As long as there are a minimum of maintenance, aka oil in the gear those things works.
art
Super Member
Going back to days of old straight cut spur gears were easy to cut and worked just fine but with the farm tractors they got so big to move the horsepower to the wheel they started using planetary gears in the rears to transmit the power. Most planetary systems are three gear and of coarse the four gear can transmit more horsepower reliably in a more compact space then the bull gears which is essentially old technology.
Texasmark
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- Ford: '88 3910 Series II, '65 3000; '07 6530C Branson with FEL, 2020 LS MT225S. All Diesels
Nope. My 2 smaller Fords are bull geared and the 3910 is planetary. I haven't bothered to look up why. Obviously there is a reason since a lot more parts are involved. May have something to do with the wet brakes on the 3910 and in doing that a planetary setup may have been more advantageous, or maybe a lower gear ratio for the same sized housing that would have to increase to increase it with a bull gear.