How smoothly should a nose wheel turn

UnPossible · #1 03-12-2014, 10:26 AM

Hey - I've been posting about a problem I've been having in the RV-7 forum about a "clunk" I have been hearing when landing. Since there are many 6,8,9 and 10's with nose wheels, I thought I'd post my question here.

One item that was suggested to check was the breakout force and to grease the nose wheel.

I have greased the nose wheel pivot joint, and measured the break out force in the low to mid 20lb range. But now that I think about it, the nose wheel has seemed to get a bit "stickier" over the past few months. When I use the tow bar to turn the wheel, it doesn't turn smoothly, it seems to want to move in short "hops."

I wonder if the "clunk" I am feeling is the same "hopping" friction when the wheel straightens out on landing.

I know that there needs to be some resistance (i.e. breakout force), but how smoothly should the nose wheel turn side to side?

Thanks,
Jason

PerfTech · #2 03-12-2014, 01:05 PM

Quote:

Originally Posted by UnPossible

Hey - I've been posting about a problem I've been having in the RV-7 forum about a "clunk" I have been hearing when landing. Since there are many 6,8,9 and 10's with nose wheels, I thought I'd post my question here.

One item that was suggested to check was the breakout force and to grease the nose wheel.

I have greased the nose wheel pivot joint, and measured the break out force in the low to mid 20lb range. But now that I think about it, the nose wheel has seemed to get a bit "stickier" over the past few months. When I use the tow bar to turn the wheel, it doesn't turn smoothly, it seems to want to move in short "hops."

I wonder if the "clunk" I am feeling is the same "hopping" friction when the wheel straightens out on landing.

I know that there needs to be some resistance (i.e. breakout force), but how smoothly should the nose wheel turn side to side?

Thanks,
Jason

... Check the nose gear mounting bolt for play. This is often the problem and will ruin the hole in the motor mount if run loose...

UnPossible · #3 03-12-2014, 01:12 PM

Quote:

Originally Posted by PerfTech

... Check the nose gear mounting bolt for play. This is often the problem and will ruin the hole in the motor mount if run loose...

I did a quick check last weekend and the bolt and the motor mount seemed fine..... I'll do a more detailed inspection shortly, but looking for any other reasons that might be leading to my "chunk"

AlexPeterson · #4 03-12-2014, 01:42 PM

Quote:

Originally Posted by PerfTech

... Check the nose gear mounting bolt for play. This is often the problem and will ruin the hole in the motor mount if run loose...

It should be noted that, with this bolt properly torqued, the gear socket may not clamp on the gear leg. I.e., the nut's function is only to keep the bolt from falling out. I know in mine (and others I've crossed paths with), the mount is not deflected enough by the properly torqued bolt to apply pressure to the gear leg. If one simply torques that bolt until the gear leg no longer moves, it may be severely over-torqued.

UnPossible · #5 03-12-2014, 08:20 PM

I am definitely going to check the torque on the nose gear leg bolt...

However, I am still curious, how smoothly everyone else's nose gear turns... does is swing smoothly (albeit with some resistance from the breakout force), or does it "hop" a bit when turning?

Walt · #6 03-13-2014, 06:00 AM

It should rotate smoothly.

gasman · #7 03-13-2014, 01:11 PM

It should swing smoothly from stop to stop when applying a constant pull... like with your test scale. The scale value should stay the same during the pull. Remove the nut and figure what is causing the problem.

AlexPeterson · #8 03-13-2014, 08:23 PM

Quote:

Originally Posted by UnPossible

I am definitely going to check the torque on the nose gear leg bolt...

However, I am still curious, how smoothly everyone else's nose gear turns... does is swing smoothly (albeit with some resistance from the breakout force), or does it "hop" a bit when turning?

Jason, it is normal for them to "stutter" a bit when pulling from side to side, depending on how fast you pull. It is a normal artifact of a system transitioning between static and kinetic friction in the pivot, with a spring (nose gear leg) thrown in for good measure. If you pull relatively quickly and smoothly, you may get a continuous movement. But, if you pull slowly, you can expect the start/stop behavior. This may not be noticeable when the nose wheel is on the ground. If I hear it on the ground, I know it needs a couple pumps of grease.