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Noisy gearbox


searcyfarms
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Rhythmical growling/whirrling sound like a bearing upon disassembly i find no noisy bearings or damaged races - one pitted tooth on large gear - stretch/stress marks on most all teeth of small gear and wear on it - thoughts ? Rhino batwing gearbox  

 

sorry about the misplacement i meant for this to go to the technical spot but missed it trying to add pix from phone 

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What’s your familiarity with this machine? If its had a gear replaced it might just be noisy. You are looking for a nice oval wear spot at the center of the tooth, if it’s crescent shaped at the edge shim the pinion gear in, crescent shape in the valley shim out. Its hard for me to see on that picture but it kind of looks like the gears are too far apart. Its also possible without enough preload you are experiencing some flexing under load that you cant duplicate by hand.  
get some red lead , reassemble and examine the contact points, that will tell you loads. Be interesting to put a dial indicator on to check lash as well. 

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5 minutes ago, Dirt_Floor_Poor said:

If the gears don’t seem to be shimmed way too tight or way too loose and the bearings look ok then I would just put corn head grease in it and run it. 

 

5 minutes ago, Dirt_Floor_Poor said:

If the gears don’t seem to be shimmed way too tight or way too loose and the bearings look ok then I would just put corn head grease in it and run it. 

 

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this mower has been my buddies for 20 yrs + he has used it to mow crp and large trees of his liking to the tune of tearing out seals and it drained the center divider gearbox and it grenaded and was made a donor mower about 12 yrs ago due to not being able to get a divider box or parts for it at the time. - FFWD 12 yrs and im resurrecting for two reasons, one so i dont have to fix his stuff he tears up all teh time and two so I dont have to road things back/forth, i need something for my work to be reliable and usable. A china based company is now making these gearboxes for Rhino and Servus for these center/divider box - i want it to be reliable and not come apart - a new wing gearbox is available for about 650 bucks so trying to see if its worth fixing this one as it had to come off anyway, the noise is growly and easily heard over the tractor and mower a WOT standing outside of it - 

this was the side of the mower my buddy used predominately for backing or dragging over trees and then trying to get off the stumps as you can see by the stump humper, both sides of the stump jumper are rolled up like that almost at a 90degree angle,  i will be straightening the stump jumper and also fixing the welds where the blades bold on because the welds  are cracked/tearing out where he was whacking things so hard with it and chewing up oversized stuff - incidenly he tore the pto clutch cage out of his 2-105 from these kinds of antics - ripped the center out of the clutch hub so it would not build pressure anymore - this mower has had no grace from him 🙈

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these are the stress marks that look like the teeth are trying to roll over or shock marks i would call them maybe ? they are on EVERY tooth to the same degree but the large gear has no signs of wear or anything 

 

you can also see on the upper edges of the took the gear are worn in about 50 thousandths not sure if that is causing the noise either 

 

 

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I would assume the ends of the gear teeth were beveled during manufacturing but I can't see it that good on my phone. With those wear marks and pits it's never gonna be quiet. 

How much is the gear and the bearings new? 

Personally if your absolutely sure the bearings are good I would put it back together with your choice of lube and run it. 

If the noise bothers you as in too annoying put a new box on it and keep it for a spare in case of emergeny? That is if a new gear and bearings is more than a box, which i suspect it will be.

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3 hours ago, iowaboy1965 said:

I would assume the ends of the gear teeth were beveled during manufacturing but I can't see it that good on my phone. With those wear marks and pits it's never gonna be quiet. 

How much is the gear and the bearings new? 

Personally if your absolutely sure the bearings are good I would put it back together with your choice of lube and run it. 

If the noise bothers you as in too annoying put a new box on it and keep it for a spare in case of emergeny? That is if a new gear and bearings is more than a box, which i suspect it will be.

it doesnt bother me that much but I was concerned because I saw shavings on my wooden dipstick i stuck in to check grease level with when it wasnt coming out of the check/fill hole, i wanted to see how full it was and if any water was in it before I fired it up and well, it was a lil milky and that made teh filings show up in it - the grrr grrrr noise isnt horrible i just dont like blowing up things and costing more $$ so thot I would investigate it - so here i am - i will say it gets louder after you run it a while - presuming as teh grease thins up

 

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49 minutes ago, oleman said:

Did you keep gear box's topped off with Deere corn-head grease?

no i have not, my buddy ran 80/90, in things till seals went out then he starts running gun grease 

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There are terms as accelerated wear which your small gear pinion is displaying possibly now worn through surface hardening, depends on how much you use it, I would go with lube suggestions provided, replace pinion and ring if parts available or pinion only or new gearbox if this is critical required and rest is in good shape 

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Bearing race that can be seen in the housing looks a little tired but could be the lighting. As VT said perhaps you can shim them for a little better engagement; the wear appears to be at one end. It's been working hard so probably won't ever be quiet. Personally I'd reseal it and run heavy oil, maybe an EP type rather than grease. I know the boxes on my bat wing finish will get very hot in tall grass and oil will transfer that heat away to the housing and out better than grease. My bush hog is now just a home for the mice or whatever is living under it. I'm amazed at the abuse it took and survived; it looks it too.

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From my experience with situations like this is that stuff like that will last for quite awhile, then all of a sudden fail. the pictures of the wear & pitting look to me like a classic case of a failed hardening of the gear. The surface and wear points are hardened leaving the metal underneath softer to allow for shock & impact, much as a good knife is hardened on the edge with the back and interior metal being a bit softer to allow for flexibility or the entire thing shatters. Although not often, the hardening does occasionally wear out or off if it was not hardened exactly right. This appears to be a classic of hardness failure. When gears are right they both should show an equal amount of wear.

 The remedy is to replace all the worn gears before they dissemble themselves and knock out all the bearings and the case as well. Also known as all gone ka-fluey.☹️

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10 minutes ago, jass1660 said:

Corn head grease doesn’t have the ability to stay on the gears the way a quality ep oil does.

i did find this https://www.cenex.com/~/media/cenex/files/lubricants/cornhead grease/corn head grease_pds-h9-02.ashx about their cornhead grease not sure if all created equal

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It sure doesn’t look that bad to me. It looks worn, but useable. If it is critical for this mower to run, then overhaul or replace it. Whatever you do I would put corn head grease in it, even if you put a brand new box on it. If you mow over something that knocks the bottom seal out, it will drain it in a very short amount of time with gear oil in it.  It’s usually net wrap that destroys the seal around here. With corn head grease, they leak so slowly, even with a damaged seal, that you can almost always catch it before the box fails from lack of lubrication. All of our rotary mowers have John Deere corn head grease in them and I have yet to have a failure from lubrication. I would not put gun grease in it. Corn head grease from Deere is grade “0”. I’m sure you could get it in lots of places. 

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Rhino does have some special synthetic oil they want you to run in the gear boxes on the new machines. Make sure you keep track of the gears, don't want to say Im speaking from experience but it's easy to get the gears swapped around and then you have to tear it all down again.

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To me it looks like that pinion needs to be shimmed in. It probably wont ever be quiet again but you can at least set it up right this time. 

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i have found a supply for the gears/bearings/seals outside of rhino, they source from the only available supplier and hike up the prices - same guy i got the divider box from but its 6 mos to get a complete gearbox as they are not stocked here in the US but parts are. I will be ordering parts tomorrow and NOT from rhino.  I called them today for their version of the prices - im ashamed at what we pay for stuff here knowing its from the same guy/supplier. Rhino quit making the gearboxes and parts in 06 for these mowers and many other servus - rhino models used them - that is why this mower sat. Now that parts are available again and rhino decided to get back in the game with parts i am able to resurrect it. 

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In an industrial gearbox it would not be unusual to feed two or three pinions to a bull gear, also flipping a gear when the arrangement allows is common. If you run grease in your box to prevent leaking.....I get that...... but I would pour some heavy gear lube in with it due to the RPM.

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From what I see those gears need replaced. When pitting and flaking occurs the case hard surfaces are worn through. Wear will only be accelerated because of softer metal underneath. I would replace all gears and bearings since you said that they were available now. I would run synthetic gear oil and it should last a long time 

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