Teupen 69A boom angle sensor

[Jehinten]

This is my buddies lift. He has had a problem for a while where the lower boom would intermittently not slide out, and recently got to where it basically never worked.

I looked it over and determined that since the lower boom must be fully raised before the boom would slide out, that there must be an angle sensor. I found it located at the marked pin (on the opposite side of the boom shown)

He took the limit switches out, which allowed them to fully extend and the lift would slide out properly, confirming that it was an adjustment of the sensors. He then unbolted the cam and rotated it and now everything works correctly.

My question is, with all of the witness marks showing that nothing has moved, how does it get out of alignment? If it was caused by wear, which I didn't see any, it would be more likely that the switch not read the retracted reading not the extended reading. The black is a dry graphite spray that I put on there after cleaning it, in hopes that it would fix it.



Has anyone else had this, with this lift or any other?

 

[Reach]

I haven't seen it on that lift, but those style switches are notorious for getting sticky. If that switch does not pop out like it is supposed to, it will not give an accurate reading. It will simply say that the boom is always down. Those switches also operate on a rather low voltage system, so the tiniest bit of corrosion or dust on the contacts can prevent them from reading as well.

 

[Jehinten]

I haven't seen it on that lift, but those style switches are notorious for getting sticky. If that switch does not pop out like it is supposed to, it will not give an accurate reading. It will simply say that the boom is always down. Those switches also operate on a rather low voltage system, so the tiniest bit of corrosion or dust on the contacts can prevent them from reading as well.

I thought the same on them sticking, which is why I started with cleaning and lubrication. The puzzling part is that they made contact on the rollers and followed the cam correctly, they just couldn't extend that last little bit (due to not going far enough into that recessed section) to actuate the sensor.

Pic is when the boom was fully raised

 

[Reach]

I thought the same on them sticking, which is why I started with cleaning and lubrication. The puzzling part is that they made contact on the rollers and followed the cam correctly, they just couldn't extend that last little bit (due to not going far enough into that recessed section) to actuate the sensor.

Pic is when the boom was fully raised

All it takes is a little stickiness, caused by some dust or corrosion, and they won't work properly. Those lifts are very sensitive.