What can be reasons of gears braking on Dyno test?
What can be reasons of gears braking on Dyno test?
(OP)
Hi,
We are making 400cc Triple Cylinder 4 stroke Air cooled engine for Motorcycle and on Dyno tests we are facing the problem of Gears braking (tooth getting sheared off) Can any one from the same field give me possible reasons for this? What tests / checking we should perform? And possible solutions also?
Regards,
LK
We are making 400cc Triple Cylinder 4 stroke Air cooled engine for Motorcycle and on Dyno tests we are facing the problem of Gears braking (tooth getting sheared off) Can any one from the same field give me possible reasons for this? What tests / checking we should perform? And possible solutions also?
Regards,
LK





RE: What can be reasons of gears braking on Dyno test?
Regards
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RE: What can be reasons of gears braking on Dyno test?
Was a Wrench or spare parts left in the gearbox?
Is it a new design gearbox, integral with the engine?
Analysis of the broken and surviving teeth and some new gear sets is an important step. There are several gearhandbooks that show different kinds of tooth failures and have discussions of causes.
Poor metallurgy is a little hard to detect, but magnetic particle inspection >should< show new gears to be flaw free, especially in the roots, and in the same areas where the teeth broke. hardness tests might be revealing.
RE: What can be reasons of gears braking on Dyno test?
Also, if the gearbox is of original design, make sure that instantaneous torque loads through the gearbox do not exceed the allowable tooth bending loads experienced by the transmission gears. The magnitude of the sum of the instantaneous cranking torques in a 3 cylinder, 2-cycle engine can exceed the mean torque by several factors. And that instant torque spike load can be compounded by dynamic tooth loading effects if your gear mesh has a low contact ratio.
Of course, the most valuable engineering lesson you're going to learn from all of this is that engine development is always expensive. The mathematical relationship between horsepower and development cost is an exponential one.
RE: What can be reasons of gears braking on Dyno test?
2. Is there a sufficient vibration damper on the output of the gearbox? Normally the sprocket carrier on the rear wheel is linked to the rear wheel itself by several rubber dampers, again to absorb shock loads and vibration.
Haven't had it happen myself (because I've always used OEM rear wheels) but some so-called "high performance" lightweight wheels don't have vibration dampers between the sprocket and the wheel, and they can smash up a gearbox.
RE: What can be reasons of gears braking on Dyno test?
Cheers
I don't know anything but the people that do.
RE: What can be reasons of gears braking on Dyno test?
bad materials
bad hardening process
misalignment (tip/root/edge contact
large pitch errors
backlash too small
I could go on...
You should probably consult a gear designer
IMHO vibration is usually a 2nd order effect, even if it is really bad.
M
--
Dr Michael F Platten
RE: What can be reasons of gears braking on Dyno test?
RE: What can be reasons of gears braking on Dyno test?
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