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Discussion Starter #1
Can anyone please help,
I have a 30 inch Mower deck with model 106 gearbox right angle drive, the big gear is worn badly.
I will probably end up buying a new gear set but I need to find a copy of the Gravely repair manual to set up the gearset so they have the correct Pinion gear mounting distance, Preload and Backlash.
Does anyone know or have a copy of this manual for the 106 model gearbox?
Thanks for any help.
 

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There is no spec for any of that. There is no preloading. All manuals are at gravelymanuals.com

Rich
 

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While there are no real specs. The bearings are adjusted in the gear housing using the lock nut above the small gear. In the swivel casting the bearings are adjusted using the lock nut holding the clutch to the horizontal shaft. Both are adjusted similar to a trailer axle. Tighten to remove all play then back off nut a bit to allow a little play. The gear lash is adjusted using shims or thicker or thinner gaskets between the swivel casting and the gear housing. You want to remove as much lash as possible while allowing the gears to turn smoothly. There is also a small seal in a metal housing within the swivel casting behind the bearing near the large gear. To remove drive the seal/housing out along with the bearing race. If you are lucky it will also drive the seal from the housing. It will usually bend or damage the seal housing but you can straighten out using some sockets or pipe ect. the CR# for the seal is 8017 if you can't save the seal housing the is a fella on Ebay that sells replacements

Todd
 

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Daryl G
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While there are no real specs. The bearings are adjusted in the gear housing using the lock nut above the small gear. In the swivel casting the bearings are adjusted using the lock nut holding the clutch to the horizontal shaft. Both are adjusted similar to a trailer axle. Tighten to remove all play then back off nut a bit to allow a little play. The gear lash is adjusted using shims or thicker or thinner gaskets between the swivel casting and the gear housing. You want to remove as much lash as possible while allowing the gears to turn smoothly. There is also a small seal in a metal housing within the swivel casting behind the bearing near the large gear. To remove drive the seal/housing out along with the bearing race. If you are lucky it will also drive the seal from the housing. It will usually bend or damage the seal housing but you can straighten out using some sockets or pipe ect. the CR# for the seal is 8017 if you can't save the seal housing the is a fella on Ebay that sells replacements

Todd
I have nothing to add other than to say that I am so happy that Toddnails is on here - so, thank you Toddnails! You have helped me more than you can imagine.
 

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The easy way to remove the bearing cup without damaging the seal retainer is to take a welder and run a bead around the inside circumference of the cup. Let it cool and the bearing cup will fall out.
 

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Richard

Yes. That is also a good method to remove the bearing race, but you still need to remove the seal from the seal housing. I consider myself quite lucky to have access to welders, pullers, presses, lathes and other implements of mass destruction, that the average owner doesn't have. But these machines were designed to be repaired by the average "Joe" without any special tools.

Todd
 

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Discussion Starter #7
Thanks everyone for your help, The small driven gear on the shaft that turns the blade, the nut came loose (last year) and I took it apart and made up a collapsible spacer out of some exhaust tubing. I measured the distance between the two "Tapered Roller Bearings" and made it an 1/8 inch longer and drilled 4 holes in the middle of the tube so now the nut needs about 130 lbf.ft to begin to collapse the spacer. I tightened it like a Diff Final drive pinion bearing preload and set the running torque of the shaft to 10 lbf.in. (easy to turn by hand)
This has stopped the nut from working loose while still maintaining a small amount of running torque on the two bearings and keeping the gear tight against the shim and bearing shoulder.
I am going to take your advise and set the backlash to zero by shimming the large drive gear and swivel housing and then shim it out to approximately 0.003" to 0.004" thousands backlash and just give it a go and see what happens.
Although the gears are worn and noisy when in operation I thought if I set them to Factory Spec it would be the best place to start from.
I am using SAE 90 oil mixed with a 1/2 a measure cup of EP Grease to thicken the oil.
I have tried this previous and it cuts down the noise a little, I had the screw plug off the top of the gearbox last week after finishing mowing some thick grass and I contemplated while eating a Banana should I put the skins in the gearbox and refit the screw plug???
I had one of those "Shall I or Shan't I" moments! ! ! anyway I threw the Banana skin away and screwed the plug back on and thought no I will try Factory settings first,
as I write a pound of Banana's on the shopping list!
 

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I should have also said that once the race falls out so will the seal retainer. Once the retainer is out then changing the seal is possible.
 

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Call Richard's L&G and ask for Jamie. He will know the new part numbers. You can also go to their website gravelyparts.com
 

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Daryl G
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Can anyone recommend a part number for the two gears for the model 106 gearbox and where can they be purchased?
Roadranger #18,
I am willing to bet that those gears will not be inexpensive! What is the availability of Gravely equipment in your country? I often see complete 30" 106 decks listed on Craigslist for $100 US. As a backup plan, 106 parts can be found on Ebay but you never know what the real condition actually is (in fact, there are some there now but shipping could be prohibitively expensive).

Take a look at this: https://www.gravelymanuals.com/pdf/30_Inch_Mower_IPL_0173.pdf. I think that these are the two parts you need:
#21 12862P1 - Bevel Gear
#31 12850P1 - Bevel Gear
 

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Roadranger # 18

I am guessing that your rotor shaft nut is not slotted, or a castle nut. And there is no hole in the shaft for a cotter key. If that is the case a new 5/8-18 thin lock nut is needed. It is the same nut used on the clutch, and also on the drive axles. If a new one is hard to find you could use one of your axle nuts. Or squash the locking side of the nut using a big hammer or press. Or use a hammer and punch to lock it after tightening. There is no reason to use a "crush sleeve". I think you will find the gears are NLA. The only option would to find used gears or a drive assembly. If your mower does work and is only noisy, some heaver oil or a banana peel might help. It might surprise you and out live you.

Todd
 

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Discussion Starter #13
Thanks Toddnails.
I used a collapsible spacer to achieve the torque on the nut so it would nut undo itself, also to guarantee that the gear was held in alignment with the two tapered roller bearings to help with tooth contact pattern under varying load.
As it turned out the retaining nut is very tight and the light bearing preload has not changed but the noise of the gears when running is a little hard on the Ears.
 

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Discussion Starter #14
Toddnails.
Incidentally the cost to manufacture here in NZ is 600 US dollars and even more if I get made in Spiral Bevel, but at least it might be quieter (I hope).
 

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All your bearings and races in the swivel casting and gear housing are smooth without wear and pitting right? I have had some mowers with badly worn gears, but have never heard them "sing" louder than than the tractor. Can you post photos of the gears?

Todd
 

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Discussion Starter #16
Toddnails,
All the tapered roller bearings are in very good condition with no corrosion or pitting on any of the races. The problem is probably more to do with it being a "Straight Cut Bevel Gear" which is noisy by default and made worse by some pitting on the big gear and some smaller pitting on the small gear. The reason for the noise being louder than normal is because I fitted a 16 hp Chonda which runs so quiet compared to the Studebaker T head engine.
It has so much more power without vibration and starts 1 easy pull with an auto decompresser now all I can hear is a noisy gear box.
Gear cutting specialist say an equivalent Spiral Bevel cut gear set will be very quiet, or a straight bevel cut with a modification to the end of the tooth can cut down the noise tooth engagement as well.
As I live in a Rural area I Mow the roadside next to my house and my wife said she can hear the noise coming down the road.
I Guess it wasn't that noticeable with the T head engine.
I can't get photos of the gears as it is assembled but when I strip it down I will post some pictures
 

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Assuming it is the while from the gears, what soft of backlash do you have in the gears? If ther gears are too loose or too tight, either condition will cause a lot of noise. Also check that the safety clutch is not loose on the input shaft.

You might also check to make sure that the output shaft is not loose and has little to no radial play. A slight amount of axial play (.005" or so) is needed.
 

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Roadranger
You did not say you re-powered the tractor HP rating x 3. How many RPMs is that motor turning at load and no load?

Todd
 
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