Looking for some input on the DX Engineering TB-400 thrust bearing.
Here is the scenario:
Rohn 55 tower supporting a large 6 meter EME array, in an "H" configuration.
4 yagis , each with 50' boom, and the main boom is also 50 '.
The total weight is approx. 700 lbs.
The rotor is one of Kurt's prop pitches, the small version (9,000:1).
I believe the max thrust that can be handled by this rotor is 500 lbs. or
so.
We have purchased the DXE-TB400 thrust bearing to be installed on the BPL55G
flat top. The hope is that this bearing can be used to support the entire
weight
of the array, thereby eliminating any thrust load on the rotor.
Problem is, the documentation that comes with the bearing does not specify
a max
thrust load for it, nor does it give a torque specification for the three
set screws
that tighten against the mast. Furthermore, the upper half of the bearing
is cast aluminum,
so the threads for the 3 3/8" stainless set screws are aluminum. My gut
feeling is that
the aluminum threads are going to strip out before we can get enough
torque on them
to prevent the mast from slipping down and putting the entire weight of the
array
onto the prop pitch rotor.
I am in no way suggesting that the bearing is not a good quality part.
But I am concerned that we are asking too much of it.
Another concern is that the bearing doesn't come with a grease fitting.
This setup is located near the coast of Oregon, they get a lot of rain
there.
Anybody have suggestions how we can improve this setup?
All input is appreciated.
Tom Hellem
K0SN
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|