Rotary Cutter Gearbox HOT???

[agford4x4]

I just bought a 6' rotary cutter, slip clutch, chains, etc. I used it yesterday to cut some grass about 8-12" high. I noticed that when i was done, after about 1.5 hours, the gearbox on it was so hot you couldnt hold your hand on if for more than a few seconds. It never made noise, never vibrated, its got oil in it. I called the manufacturer and he said "if she has oil, its got a warranty, use the **** out of it and if it blows up, well send you a new gearbox". He said some run hotter than others so its hard to tell. Honestly, ive never touched the gearboxes on my other shredders, so i don't know if its normal cause its new and not 'broke in' or what.

 

[art]

When new they will normally run hot or more so then when they are broken in. Now you said to hot to touch and I don't think I'd want to hold my hand on one either! I'd say temps of 100 to 150 would not be unusual but exceeding 200 would be to much.

 

[scott_vt]

Afternoon Agford,
As long as the gear lube is at the proper level, I would do just like the manufacturer suggested ! Run it hard, that whats its designed to do, and if it fails you get another one !

If its not making any noise I seriously doubt that you have a mechanical issue , bad bearings etc....

 

[agford4x4]

Cool. That makes me feel better. I just didnt know, because like most normal people, i have never shredded and then jumped off and went and touched the gearbox. I would HOPE that IF something was wrong, it would fail within the warranty period. I have a lot of work to do with it, so its not like its not going to have a chance to do just that. Otherwise, it works well, the clutch works well too. Thanks for the info folks, i appreciate it!

 

[greg_g]

If you mow in a warm climate, you might want to replace the OE gear oil with something thicker. My mowers came with what I assume was 80W90, maybe even straight 90W. Hot weather mowing thins it out too much to suit me, I've changed to 85W140. If that's still too thin, I'll probably go straight 140W

//greg//

 

[Soundguy]

I agree with the others... if it's got lube, and not making noise.. and the paint ain't burned off.. then it's probably ok.

My 10' and 15' mowers are hot enough to not hold your hand to for more than a second or so after mowing 10 ac.. etc..

it is a mechanical device working.. and wast energy is heat.. so.... I think you are ok..

Soundguy

 

[Soundguy]

If you mow in a warm climate, you might want to replace the OE gear oil with something thicker. My mowers came with what I assume was 80W90, maybe even straight 90W. Hot weather mowing thins it out too much to suit me, I've changed to 85W140. If that's still too thin, I'll probably go straight 140W

//greg//

I agree. I('ve got one mower that even says you can mix grease with the gear oil to stabilize it...

Soundguy

 

[agford4x4]

Good. Ill just go with it. Its a Mohawk Cutter. I don't think there is a good way to change the oil. I don't see a drain plug, i dont guess its designed to be changed much. I guess you have to suck it out the filler hole.

 

[john_bud]

Good. Ill just go with it. Its a Mohawk Cutter. I don't think there is a good way to change the oil. I don't see a drain plug, i dont guess its designed to be changed much. I guess you have to suck it out the filler hole.

Yeah, turkey baster used to suck the old oil out. Or do it the redneck way and flip it over with the FEL.

Normal operating temps for a gear box of this type are in the 160-180F range. 200-225F is not unusual or abnormal when running on a hot hot day in the thick stuff. It actually sounds like yours is on the cool side. You WANT it to be hot enough to burn out the moisture that collects in there from condensation, so too cool is not good.

Old school rule of thumb, is burning paint is too hot. Then again, if the paint is burning, so are the bearings....

jb

 

[HayDR]

I just bought a 6' rotary cutter, slip clutch, chains, etc. I used it yesterday to cut some grass about 8-12" high. I noticed that when i was done, after about 1.5 hours, the gearbox on it was so hot you couldnt hold your hand on if for more than a few seconds. It never made noise, never vibrated, its got oil in it. I called the manufacturer and he said "if she has oil, its got a warranty, use the **** out of it and if it blows up, well send you a new gearbox". He said some run hotter than others so its hard to tell. Honestly, ive never touched the gearboxes on my other shredders, so i don't know if its normal cause its new and not 'broke in' or what.

Most rotary cutters gearboxes run 40-60 degrees above the ambient temperature.

 

[greg_g]

If not already so equipped, a vented fill plug will help the tranny run a few degrees cooler. I've got an extra, if the diameter is right for your fill threads.

//greg//

 

[N80]

I've noticed these types of things before and wondered about them. There should be two types of owner's manuals. One for the basics, one for completely new users who will be nervous about warm gearboxes, etc. I was surprised at one point to feel how hot the tranny/diff on my gear drive tractor was after some hard work one summer afternoon. It worried me until the TBN folks told it was normal.

Just the other day, its was in the 80's and I was mowing some heavy stuff and noticed the gear box on my 6' cutter was quite warm. I could hold my hand on it so I figured it was okay.

But this is the type of thing that new tractor owners are not going to have an intuitive feel for. We might guess a tranny or gearbox might get warm, but how warm? Fortunately, we have TBN and its collective experience/wisdom.

I am going to be changing my gear oil this weekend and since it typically gets into the mid 90's here in summer I think I am also going to go with a thicker gear oil.

 

[agford4x4]

yeah, thats why i asked here. Oddly enough, these boards have more knowledgable people on about specific products than can be found at the manufacturer 99% of the time.

Like i said, i used my folks shredder, but i never hopped off and went to check the gearbox for any reason.

 

[John_Mc]

Most rotary cutters gearboxes run 40-60 degrees above the ambient temperature.

And most people tend to overestimate how hot a piece of metal "feels". At 140 deg F, you will not be able to keep your hand on a piece of steel. This is still well within the safe range of your gearbox.

John Mc

 

[john_bud]

I've noticed these types of things before and wondered about them. There should be two types of owner's manuals. One for the basics, one for completely new users who will be nervous about warm gearboxes, etc. I was surprised at one point to feel how hot the tranny/diff on my gear drive tractor was after some hard work one summer afternoon. It worried me until the TBN folks told it was normal.
.

Too true. One thing I have noticed is that convential wisdom that the more experienced folks have can often be found in product literature from the 50's and 60's. For instance, Ford's product brochure for loaders calls out the usual stuff on time to lift, tilt, dump etc. But, it also calles out pump flow by engine RPM and at a temperature of 160 F. Obviously, if you feel a loader that is working hard and it feels hot to the touch, you may be concerned until you remember the spec called out 160F as the oil temperature where the equipment was measured -- so 160F must be normal.

When was the last time you read a product brochure that had all the technical data you could ask for, cylinder dimensions, pump flows, dyno chart, etc. The marketing branch is getting dumber about the products and the literature is going down with them. (Just my own jaded opinion)

jb

 

[B2400]

You might consider switching to a synthetic gear oil after you get some hours on it. Synthetics seem to run a little cooler. Switched my KK 48" to Mobil 1 85W140 and runs fairly cool.

 

[Rod in Forfar]

I took my laser thermometer to a new Chinese gearbox, a warranty replacement, because it was so noisy. After 50 minutes of mowing 6" grass, it ranged from 132 to 140 degrees F on various parts of the gearbox.

 

[N80]

Old thread! I've got my same JD light duty cutter. Same hot gear box. Still pushes gear oil out the vent valve if it is hot and is run hard. It was well used when I bought it and that was at least six years ago.

It runs fine, makes no noise, no vibration. I just keep the gear oil at the right level and paint over the rust spots!

 

[HayDR]

First check the vent plug. Take it off and blow through it. If you can't blow through it easy, then fix it or replace it. Typically rotary cutter boxes run 40-50 degree above ambient temperature.

 

[greg_g]

Also check the fluid level and quality. It should not be gray and foamy, nor be above the level of the side drain. FWIW, the Chinese RC that I bought some years ago didn't come with a vented fill plug, I had to find and fit one from the aftermarket.

//greg//