Cutter gearbox question for seasoned farmers, machinists and engineers

[Lockport]

I've a 3PH finish mower that turns backwards and the intent of installing Oregon's Gatorblades demands the pursuit of reversing the gearbox. The main planetary gear was located forward, at the spline accommodation, and I moved it to the rear. It works but the gear meshing is slightly louder and the heat produced at the gearbox makes it nearly too hot to touch. Initially, I thought the three spacers between the final snapring and the rear most bearing needed to be adjusted. When i removed the oil cap I noticed the force of the revolving PTO had slightly angled the shaft so that you see more of the bearing and snapring along one edge. I assume removing a spacer will only worsen the misalignment, not to mention the fact that I broke and bent the tips on two sets of snapring pliers tip sets trying to get the primary snapring out.

Am i worrying about nothing?

 

[BrinkME]

no, you're not worrying about nothing. It's louder now because there's more backlash between the gears, which will cause higher stresses on the gears, more friction, and added heat ... all bad things to have.

 

[npalen]

First of all, a disclaimer: I'm not seasoned but have been cooked and well done a few times over the years.
The mowers that I'm familiar with would have a pair of bevel gears and could be reversed by moving the driving gear to the opposite side as you mention. It sounds to me like the gears are meshing too tight causing the heat and could probably be remedied with shims by someone familiar with the process. Seeing more of the bearing and snap ring along one edge may be caused by manufacturing tolerances of rough castings rather than shaft misalignment. Hard to say without seeing it in person.

 

[kthompson]

Are you sure they do not make the blades you need for your mower in the original set up?

 

[Lockport]

The tractor PTO turns clockwise when facing and the gearbox on the cutter, counter-clockwise by design. Originally, the spline seats at the rear, and probably poorly machined, bearing accommodations before an oil seal and the facing drive gear was at the forward side, turning the horizontal beveled gear counter-clockwise. By moving the drive gear to the rear, the horIzontal gear turns clockwise and accommodates the proper direction to utilize the Gatorblades. However, since there is no longer the resistance created by the distance of a frontal orientation and the spline seated at the rear of the gearbox, the spline has slightly forced itself askew. If I turn the gearbox around, which I can because there is a spline seal on one side and an oil cap on the other, it doesn't resolve the fact that the drive gear still turns counter clockwise and must be at the rear of the gearbox. So you're correct npalen and I agree, I thinks it's our tolerances in the casing. Spacers at the front spline seem to be the only possibility.

BrinkME:
I'm still wondering exactly what kind of damage I might suffer just leaving it the way it is as I don't see an immediate resolve and refuse to live without my Gatorblades. I've got Royal Purple Synthetic gear oil inside.

kthompson:
This finish mower is one that Doosan had made when they briefly sold Kioti tractors under the Bobcat brand. The mower is not a Kioti mower but was one made to their specifications. The blades I sized top match address made by Oregon, famous for chainsaw blades, and address the Gatorblade brand. These address sized to match. In other words Gatorblades address made specifically to many, many mower's but sometimes you have to size them. I used to have a Kubota BX2230 and found identical dimension blades but have to utilize a reducer for the center mounting hole. All Gatorblades are same side cutting edge and cannot be b'way flipped by design. Google them and you'll see.

Thanks all!

 

[Leejohn]

Try re shimming and get about .025 backlash, then should run cooler and with less noise.

 

[kthompson]

Lockport, not saying you are not right. Just know they make many different blades. I used Gatorblades for about two years and went back to factory blades on my Bushog brand mowers. For me the Gatorblade did not do any better job. No doubt the type of grass and other conditions could be the reason.

 

[Lockport]

Leejohn: when I reversed it, there were two spacers at the front and three at the rear. I reassembled it the same and it was tight. I think once the spline, seated at the rear where it's ability to counter the resistance against the bevel gear, was subject the the bevel gear moved that much closer to it, at the same time the fulcrum of resistance was reduced may prove there is no solution to my problem. So i wacked the front of the spline with a small mallet against a piece of wood and cut the lawn. Second guessing, it's not dramatically louder than it was, nor hotter. Though I'm sure it is. My rotary cutter gets as hot. You can't keep your hand on it's gearbox after a couple hours in the field.

kthompson: could be for your Bushog. I've always sworn by Gatorblades but the point I was making was that the cutting edge on all is on the same side of the blade. That being said, this is an open rear finish mower and its inability to create as much air turbulence than a closed deck is certainly a consideration. It's still outperformed the stock blades.

 

[CalG]

quick test

How much free play or lash do you get when rocking the input shaft?

None is no good, A lot is no good either. A little is just right. As mentioned .025" would be fine.

 

[Leejohn]

One thing I forgot to say is if it's a race and cone bearing the preload has to be set. To tight it well run hot and loud, about 10 to 12 rolling in lbs.is about right Roller bearings don't need a preload set.