R: [amsat-bb] G5400B Elevation ballbearings size ?

["i8cvs" <domenico.i8cvs@xxxxxx>]

Hi Frank,

The size of ball bearings for the elevation motor type KR500 is 0,312
 ( 5/16 inch )

The size of ball bearing for the azimutal motors type KR 400 is
0,375 ( 3/8 ) inch

I dont know the ball situation for G5400B but i would like to add some
comments on this matter.

The problem in the class of elevation motors like KR500 and up is
the weight of the antennas loaded on the mast wich is applied vertically to
both bearings.

This vertical force divide itself in to two ortogonal components that
tends to bend and break the teeth of the steel bearing holders (spare part
33, 34 )

As soon one thoot of the bearing holder is bended or broken than
the two adiacent balls get in contacts between them.

In this situation there is room between the balls forming the bearing
and the boom passing in to the motor tend to occupy the above
empty space and because of its weight the pinion fall a little bit down.

In this case the pinion of the assebly gear (spare part 9 ) loose a
solid contact with the assembly tube gear (spare part 31) and this
creates a situation of possible pinion  break particularly when the
bended teeth of the bearing holder are more than one.

For this reason during preventional maintenance i suggest to always
replace the two bearing holders along with the ball bearings in the
elevation
motors of the KR500 class.

The purpose of the bearing holder is to regularly space the ball
bearings one to each other all around 360 degrees in order to get room
to fill and hold the grease in between lubricating the bearing
housing.

The other function of the bearing holder is to hold the grease and prevent
the water to enter inside the rotor housing.

During normal operation the bearing holder should rotate distributing the
grease all around inside the bearing  housing but in practical situations
the bearing holder became stuck very soon because of inside deformations
and it loses completely its mechanical and lubricating  function.

Since the weight of my antennas is very high the bearing holders had
to be replaced very often creating to me a big problem and so i experimented
to remove the bearing holder completely and fill  more balls in the
available room.

If i well remember 20 balls of same original size where necessary to fill
completely the available room around 360 degrees in the bearing.

I filled the balls inside the rotor housing with black molibden grease
and it is up there on the roof from some years now without any problem.

The problems are now less than before and the only precaution is that
to periodically fill a small quantity of grease from the outside the
bearings with the pressure of a finger.

If the water tend to enter the inside of rotor housing be sure that the
bottom hole for drain is open and eventually enlarge the hole a little bit.

I hope this help

73" de i8CVS Domenico



----- Original Message -----
From: Frank Viggiano <fviggian@taconic.net>
To: <amsat-bb@AMSAT.Org>
Sent: Thursday, July 04, 2002 4:01 AM
Subject: [amsat-bb] G5400B Elevation ballbearings size ?


> Does anyone know what size the ball bearings in the G5400B Elevation rotor
> are? I want to order them before I disassemble the rotor again.I forgot to
> get the size when I had it down for inspection in the early spring....
>
> ----
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