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ANOTHER GEAR BOX FAILURE

Fatboy I wouldn't have posted anything until you spoke to the manufacture. And trust me I'm not poking at you but it wasn't even your boat and that is how it usually goes, When there is a problem the owner needs to talk to the manufacture before anyone else get's involved. I know you meant nothing by it but you might have inadevtantly made it harder for your buddy to get his stuff fixed. Not to stand up for anybody but things happen and rarely does all the information becomes known! Anyway work with the manufacture and I'm sure things will work out better for everyone involved. Gearbox failures are so few and far between but now everybody will talk about them as they happen all the time. I have seen one in ten years and I'm around a lot of them. I have seen a lot more props and hulls have problems then gearbox's. Anyway I'm glad to hear nobody was hurt and I hope it all gets worked out!
 
Those word are true, Waterthunder.

I am surprized that total drive harmonics are not discussed more on this site. We have increased horsepower, torque, propeller bite and overall "push", I read many threads about ballancing the internal parts of a motor...but, never about ballancing the overall output components. From running outboards in the guide business for way too many years, I know first hand what the results of one out-of-ballance part can be on the whole shebang. There was a conviction last year without a trial...let's not do it again until all the facts are in.
 
IMO,
Nobody should come out bashing a particular box manufacturer unless absolute proof of deliberate manufacturing flaws exist......anyone can bolt up a box, put a prop on it...set the pitch marks and not even know they are out of harmonics. I have a buddy pushing 900 plus HP on a box rated for 700 and he has no problems with it, but he also has a digital angle tool to ensure his shiat is turning the right way.
 
I'll explain it in redneck terms....... Things dat spin, need to be balanced.

Someone more qualified can get into the specifics.
 
JL242":v3anbp0n said:
I'll explain it in redneck terms....... Things dat spin, need to be balanced.
Click to expand...

Thats funny right there.

Glad to hear everybody is ok though.
 
My take on harmonics is that everything that rotates has what is known as "critical speed". I know in the utility industry we run our turbine/generator set at 3600 rpm's and it runs there day in and day out with little or no vibration. But everytime we bring the unit on line or shut it down it goes through a critical speed range where the vibration is extremenly high and if left there very long will destroy the turbine. It is explained that when the frequency of the rotatioin equals the frequency of the vibration you experience this extremenly high vibration. I know I didn't explain it very well but maybe someone else can take a stab at it.
 
You hit the nail on the head. I think the whole term I balanced my motor is way over used. You must statically balance the rotating components and then you must dynamically balance them. Here is where the problem lyes, in the past most machine shops when balancing a motor only turned the assembly around 2,500RPM or so on a lathe. Mostly because it becomes dangerous to spin them up higher on a lathe! A motor will not remain in balance across a wide RPM range because of harmonics and other causes. When I was 17 I asked a local sprint car engine builder to balance my 340 Small block Dodge at 5,000RPM’s he looked at me like I was crazy and stated he might be able to push it to 3,000RPM’s but it will not make a difference! Anyway my point is I do not believe you can truly keep a motor balanced thru out a wide RPM range! There are far to many dynamics involved that are constantly changing thru out the engines RPM range. Just like how many times have you heard my prop only shakes at such and such RPM but is smooth everywhere else. That’s because at the RPM it shakes it has become dynamically un-balanced even though at lower RPM’s it was balanced!
 
this is where a soft drive will make a difference.i don't see how harmonic indiferences could be tranferd through the bushings .on a hard drive i could understand.also a liquid filled dampner is also a good crutch to get out some vibration.
 
That cover up good old boy network crap is the same BS, that the major car makers do. Lets kill a few more before we do anything about it. Maybe it is a freak thing, lets just wait and see.

There are many reasons thing come apart. Operator error and abuse, poor maintenance, and poor design.
Holding things like this back can kill someone. Maybe you or a family member. Or just someone at a ramp.

I am no expert on gear boxes, but everybody with that particular one should be going over theirs with a fine tooth comb. It's just the right thing to do. Thats how you prevent others from getting hurt or dieing.

It don't have to be bad mouthing a product, it's more about protecting the public.

How would you feel if someone die today due to the same event happening.
If I owned that particular box, I would want to know about failures and I would want to know about them today.

Just my opinion.
 
I`m with deepsea on this.It doesn`t haft to be viewed as bad mouthing,just good info so maybe some one can find a crack before it turns bad. But no matter the box brand,every one should look there`s over. Fat boy,I hope you post those pics,be very interesting to see. And if it causes the guy any problems with warranty or anything else,that should be let out so we know who stands by there product no matter what. It should all be public knowledge,not public bashing.
 
Were this an FAA certified aircraft, every aircraft in the entire fleet would be grounded until an inspection of the suspected flange is made.

Its not about defamation, its about getting critical information out to others as rapidly as humanly possible.

If something is held back intentionally and someone does get hurt, It seems to me that THOSE WHO KNEW share in culpable negligence.

Anyway Im sure it is a simple inspection to make certain the flange is safe or unsafe in other boats.

Of course at this point is anyone sure the flange is the culprit or the result of some other culprit? Does that matter even?

Its not my dog in the fight, but if I had a similar or duplicate rig, I sure would want to know as soon as humanly possible.

Another thought though is that, THAT information should be officially forthcoming from the manufacturer. Discussion on a user forum is fine and can spread the word fast, but in the last analysis, it is up to the manufacturer to get the word out that owners need to inspect.

Maybe the case can be made that every airboat owner is responcible for inspecting his equipment every time he operates the boat. However CDL drivers are not held accountable when an 18 wheeler breaks an axle and folks are hurt. Airline pilots are not held responcible for in fllight failures.

Im sure there is a line somewhere and Im sure anyone having the same equipment wants to know as much as they can as soon as they can.

Scotty
 
I also agree with deepsea, this forum saved my butt back when powershift had problems with their sirius, went out and checked man and sure enough it had a hairline crack at the hub on one blade, called my buddy and told him and he checked his and had two blades cracked. If I had not have read this I probably would not have went out there and checked it that close, but I do now everytime.
 
I don't care about any of that crap I just feel it's up to the actual owner or the manufacture if they want to make it public, not a third party. See I'm not a member of a good old boy network but I have seen a dozen times where and engine builder or boat builder built something for somebody and warned them don't do this or don't use that part or that will not work but the customer does anyway usually to save money and then something breaks and then some third party not even involved goes and blab's his mouth not knowing the whole story! Lets just say that box is rated for 400HP and someone put a 600HP motor with N20 on it and bang it breaks. Well nobody ever mentions that they just start running their mouth "That gearbox blew up" without even knowing any facts things like maybe somebody took it apart and put it back together wrong or ran it out of oil. Anyway my point is there should be no bad mouthing until ALL the facts and problems are sorted out! I have never used one of these gearbox's so the good old boy network comment is total BS. This is a fact because I have never even used or talked to the manufacture of the gearbox that failed! and I still will not form an opinion unless I saw it break and know why it broke. But that's just me.
 
Makes sense that the Manufacturer is the one to release any official info. You hit it right on the head about 3rd party info.

Glad everyone involved is ok.

Scotty
 
I wasn`t that clear in my post,ALL the info from both sides needs to be let out.If it was error on the owners part I`d like to know what he did so I don`t do it. If it`s the manufacturer than I`d like to know that to.I`m not for the he said she said crap either but,like was said it should be let know what happened and what caused it,Just mite save some one allot of problems.
 
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