Gearbox Oil Seal Failure

Here is one possibility. As the seal is being assembled and slid into position, one side of it may be sticky (maybe rough surface on shaft or housing). Further pushing can roll part of the seal over, making the spring fall out of position. Applying a light film of oil to the surfaces can help prevent this. For a certain type seal I use regularly, STP is really good. But be sure of fluid compatibilities, and maybe use the same oil as will go into the device.

thank u sir,

maybe possible.

but shaft surface was absolutely ok, clear & clean.

Make sure the gearbox is able to vent through a breather, if this is clogged or damaged the oil temp,or foaming can create enough pressure to blow-out the seal .

for the OP i would be checking the seal rating fitted for the application and the assembly method , maybe change to a higher quality seal , check for excessive pressure buildup and shaft end float , plus if there is any shaft shoulder impacting the seal due to excess shaft end float

another issue is that some gearboxes such as planetary's require internal pressure to minimise oil emulsification.

i have encountered such boxes where 10 PSI vent valves are fitted for that purpose.

something to be aware of where gearboxes are used in wet or harsh environments is that when the gearbox heats up it will vent pressure through that 10 PSI check / vent valve but when it cools down it could suck water and dirt past the seals.

i sometimes use harsh environment secondary seals at the external shaft with simalube auto grease injectors to give constant grease feed , and a moisture eliminator intake filter so when the gearbox cools down it can suck in dry clean air through a small check valve which still allows that 10 PSI to be maintained during operation.

complicated ? harsh environments require different approaches

hope thats helpful to people or stimulates some thoughts :)

Been there, done that and NOT got the T-Shirt.

GA for a commonsense answer.

Does the shaft have a chamfer on the end, to ease the seal open when the shaft is inserted into the seal? Rounding the chamfer with a file would make assembly even better.

Tornado had a very good point, in addition, you must make sure you have the right size, yes smooth surface, put shaft lubrication as tornado said, and make sure to insert the shaft or the seal slowly and rotate etheir shaft or the seal where ever is possible while putting the seal. Maybe the spring did not loosen only move out from the seal. If you are sure it is loosening try using another brand.

It's also possible you have the wrong type.

If heat is present you need the appropriate compound.

You may also need an elastomer static seal detail on the mounting face.

Bi directional or uni directional seal?

was the seal on the right way round ?

if not it will still leak but look ok.

internal presure will force oil past seal

Anything driving the gearbox?Any excessive vibration or speed?

Check!

My friend please make the gear box is okay. (bearings and gears are not damage, circlip And spacer in place)