thrust bearing installation

[wavekatcher]

What is the proper technique for installing the thrust bearing? I noticed the shaft on the motor has some in/out play. Do I find the half way point of this play then install the collet up against the thrust bearing?

I have it installed already. What I did is, pulled the shaft to the aft position then tightened the collet down against the thrust bearing.

[dana]

Not really the best way. The motors bearings are designed to take thrust, so IMO thrust bearings aren't necessary, but if I were using one I would just install it without trying to get rid of play.

[stumblinh]

Install the bearing in the normal rested position, you don't want the wear from being "in the middle" with constant drag and load. Not effecient.

[gyrotron]

Install the bearing in the normal rested position, you don't want the wear from being "in the middle" with constant drag and load. Not effecient.

Stum,
If you have one of these installed in your boat, can you show us some pics?
Thx

[wavekatcher]

Install the bearing in the normal rested position, you don't want the wear from being "in the middle" with constant drag and load. Not effecient.

Forgive my stupidity, What is normal rested position of the shaft? Run the motor without anything attached, then connect?

[Basstronics]

Not really the best way. The motors bearings are designed to take thrust, so IMO they're useless, but if I were using one I would just install it without trying to get rid of play.

Radial ball bearings were never designed to take thrust.

[dana]

Edit. You can take my advise on the bearing thing. They will take thrust. Thanks jay

[wavekatcher]

So, exactly where does the thrust bearing go? I still am unclear. Btwn the drivedog and prop??

[dana]

Between the collet and motor mount plate/motor can

[domwilson]

Here is a pic of how mine is installed in one of my boats....

[wavekatcher]

Thanks everyone. Looks like I did the install correctly.

[domwilson]

Make sure you pack the bearing with plenty of grease.

[Fluid]

Wow, lots of bad information in this thread....

Radial ball bearings were never designed to take thrust.

Not so. Many of the motors we use are designed for airplanes with the prop directly attached to the motor shaft. They are not only designed to take thrust, they do it very well.

I was running my motor out of the boat and it made a small amount of temp.

All electric motors build heat when run without a load because virtually all the energy goes into heat, not torque. The thrust bearing had nothing to do with heat buildup in the motor.

Install the bearing in the normal rested position, you don't want the wear from being "in the middle" with constant drag and load.

A thrust bearing does nothing if it does not transfer thrust from the prop to the hull. It does this ONLY if the bearing is pinched between the coupler and the motor under forward movement - otherwise the motor's endbell bearing is transferring all the thrust (usually not a bad thing at all). When set up correctly a thrust bearing will not be loaded when the motor isn't running, otherwise it will cause unwanted friction. If a motor shaft has axial run out - end play - measure the play and install the thrust bearing so that only half the end play remains. This will insure two things - that the bearing is actually taking thrust when the boat is moving, and that the thrust bearing is not adding friction by pinching the PTO bearing between the internal shims and the thrust bearing/coupler.

Make sure you pack the bearing with plenty of grease.

Many small bearings are not meant to be "packed with grease". Most will sling out any grease as soon as the motor spools up. You need to use a bearing oil that will stick to the races and balls for the few minutes the motor runs. What you have to remember is to re-lube the bearing after every use and don't let it rust.....



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[wavekatcher]

Thanks for the clarification Fluid. Are you sure the bearing doesn't go btwn the drive dog and prop?

[Basstronics]

Depends on bearings.

If its a radial ball bearing it will only take a small amount of thrust. If its angular it can take some more. However thrust loads are not what they were designed for.

A thrust bearing in larger applications is a good idea. There is no real con against using one... The added weight or rotating mass is negligible.

I know a few things about bearings. My last machine I was Project Engineer on I utilized a 126" thrust bearing special made in Thailand. I also utilized a ton of tapered roller bearings in spindles as it was a tube mill.