Nose wheel breakout Force

[RhodeIsland9]

Setting the breakout force on the nose wheel today and noticed the castle nut turns a little on the threads in each Direction until being stopped by the cotter pin.

I checked the plans to make sure I have the orientation of all the washers and Hardware correct.

It seems like a lot of stress to be placed on the cotter pin?

 

[larrynew]

Just did a complete service of the nose wheel and fork including removing all old grease. The castle nut is definitely too tight to turn on its own after adjusting for breakout. Could the fork bushing be binding on the axle? Doesn't sound right.

 

[RhodeIsland9]

I grease the zerk fitting until grease came out the bottom.

Do the washers stay stationary or rotate with the fork?

 

[AlexPeterson]

Setting the breakout force on the nose wheel today and noticed the castle nut turns a little on the threads in each Direction until being stopped by the cotter pin.

I checked the plans to make sure I have the orientation of all the washers and Hardware correct.

It seems like a lot of stress to be placed on the cotter pin?

I noticed this exact problem about 20 years ago upon first assembly of the gear. I somewhere found a split collar type of nut, turned a conical section onto it in a lathe. I do not like this pounding on the cotter pin either. I've searched several times since then for a source but have been unsuccessful in locating this odd thread in a split collar.

It might not take much to prevent the castle nut from rotating; perhaps some disruption of the threads would be enough. The basic problem is that the friction radius of the threads is smaller than that of the spring washers.

It also appears, given the apparent service record of this item, that no one has observed a broken cotter pin.

 

[RhodeIsland9]

I noticed this exact problem about 20 years ago upon first assembly of the gear. I somewhere found a split collar type of nut, turned a conical section onto it in a lathe. I do not like this pounding on the cotter pin either. I've searched several times since then for a source but have been unsuccessful in locating this odd thread in a split collar.

It might not take much to prevent the castle nut from rotating; perhaps some disruption of the threads would be enough. The basic problem is that the friction radius of the threads is smaller than that of the spring washers.

It also appears, given the apparent service record of this item, that no one has observed a broken cotter pin.

I think this is exactly what is happening, the friction on the threads being less than that of the spring washers.

I don't like the idea to purposely bugger up the threads on the gear but I think that might work.

Has there ever been a case of the cotter pin sheared off in normal use?

Inspecting the pin every time the tire pressure is checked might be a good idea.

 

[GalinHdz]

Inspecting the pin every time the tire pressure is checked might be a good idea.

FWIW I re-grease the nose gear during each condition inspection. So I replace the cotter pin and set the break out torque once a year. After 12yrs, it has never been an issue.