Gear box misalignment

[gearman1234]

Could anybody give information about how a misalignment in the gearbox is checked? I have one double speed constant mesh gearbox where failure has taken place due to misalignment as only one side of teeth have broken on one gear, 26T, 12DP, 23 Deg Helix.

 

[shooter45]

One way is a soft blue check under partial load.

 

[GearmanPE]

Clean the teeth and paint with layout dye from Dykem. You will have to experiment with how long to run for a good pattern check, depends on oil film thickness. If the paint film rubs off too quickly, you will be looking at a composite of deflections as you are comming up to the load being checked. Try to get the reading to take an hour or so.

To slow the reading, run cooler and thicker oil, oppisite to speed up. The idea is to read the contact at the load being investigated.

We have found red dye to work well, though blue or even white is OK.

Constant mesh gears, running on a bore bearing, will tip due to over-turning moments. This may be the problem.

 

[involute]

what will be your solution if you find that you have a misalighment????
have you changed gears in the gear box and got a misalignment subsequently? then it is due to helix angles not matching
if it is a new gear box talk to the manufacturer

 

[beloka]

You can check alignment as per the good advice you've been given.
This may sound somewhat basic but have you checked:
# The shaft design for deflection and angle of deflection at the gear. Poor shaft design can result in gross misalignment under load.
# That the bearing type and arrangement is correct. i.e correct clearances, allowance for thermal movement/float
# Is the gearing symetrical?. As the gear heats up under load will both sides of the gear expand at the same rate?.
# Is the gear running true on the shaft.(mounted properly)
# Has the gear shifted on the shaft?
# Does the gear casing temperature have any effect on alignment?.
# Does the gear casing distort under load.?
# Is there an external overhung load on the shaft that could impact on alignment?. i.e. a different position of the shafting as made possible with actual bearing clearances.

 

[gearman1234]

beloka , I appreciate your advice. I would double check .