Cutter gearbox question for seasoned farmers, machinists and engineers

[Tractor Seabee]

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?

I would think someone makes blades that accommodate the rotation of your mower spindles. Probably expensive though at it is non-standard

Ron

 

[Lockport]

Well beyond that now. Cutter turns in the proper direction. Cuts a fine lawn. Just needs a little play.

 

[kthompson]

lockport, my mower is not rear discharge. I have a 6 foot rfm by Bushog and a 52 inch ztr mower of theirs. I used the gator blades on both for about two years and found very little difference. Both are side discharge decks and for the most part was not cutting heavy grass and was being cut normally say two inches.

When I bought my rfm was not aware they made a rear discharge and when I saw one thought wish I had that. Have a friend with business that sells tractor implements and used tractors. He has a rear discharge and based upon what he said about his you may very well find grator blades helps on yours. He said the rear discharge kicks the grass out without recutting as a side discharge does.

 

[Lockport]

Before I put Gatorblades on, and even the slightest neglect of timely cutting, I would literally get furrows of green grass. I'd end up cutting my furrows, to no avail. With Gators, I find no evidence of cut grass is even visible. I also have great faith that the small bits, the evidence of the repeated cuts of the blades, is one of the best healthy lawn growth mechanisms available. Admittedly, I've only cut once asset the end of last season, and briefly cut the thatch I've lifted with my homemade 3PH dethatcher. But the season's young and so am I.

 

[PJ The Kid]

Most gearboxes have helical cut gears. They are cut this way for strength. Have you ever listened to a car in reverse at a higher speed and how loud the gearbox is? That is likely the noise you are hearing along with the preload being too tight causing the heat from friction. You can dial down the preload and it will help but will cause premature wear on the pinion and ring gear.

 

[Lockport]

After a long drive I the country I've figured out what I did wrong. When i moved the bevel gear to the rear side of it's mate, they're were two spacers behind the snap ring at the front and three at the rear and I reassembled it exactly like that. I should've put the three at the front which wound have allotted for that increase in space between the mesh as well as seat the rear of the spline further into it's seat. I think that's it.

 

[Lockport]

After much struggling and broken snap ring interchangeable tips, I finally got the front and rear snap rings out using a carpenter's counter-sinking nail punch and a couple screwdrivers. Moving what would reveal to be a 4mm spacer to the opposite side and a couple wacks with a small mallet against a piece of hardwood set on the spline I've found just enough play. I connected the drive shaft to the PTO and tested it for noise level while still open. Satisfied, I inserted my 2nd pairing of spline seal/oil caps (Bobcat $150CA, Avxseals.com $11CA!) filled it with 90 weight Royal Purple heart oil and laid a bead of black liquid gasket around the top before sealing it up. Just a hint of play, I cut for an hour and swear it runs cooler than it ever did.

And buried deep beneath coats of black paint, still with plastic film intact is the manufacturers identification plate. It's an Italian based Comer Industries gearbox. It appears to say LF-219J, which I've concluded is a derivative of the LF-205J cutters series as it matches the characteristics perfectly and as the series escalates to the 221, but that's a tiller gearbox. Moving one higher from the 205 is a 20hp, where the 205 is a 30hp 540rpm reversible gearbox. There is a center offset of 79mm compare to 83mm which appears to be the factor I ran into, albeit I should've known better than to not follow a unified amount of spacers with the orientation of the input gear.


Thanks all for the input and observations!