Model 1200K/1210K - RCI SNG ANTENNA SYSTEM 10 Operation and Maintenance Manual
SECTION 3 - AZIMUTH POSITIONING SYSTEM
3.1 AZIMUTH BEARING
The azimuth bearing is a precision ground, sealed Kaydon Slim Line ball bearing with a dynamic
and static moment capacity of over four times the worst-case wind load specification. It is press fit into a
special aluminum-bearing ring consisting of main internal and external rings with clamping
rings. The bearing is packed with synthetic grease at assembly and no further greasing is required.
Because of the excess capacity, low rpm, and low number of cycles, no maintenance is required.
3.2 AZIMUTH GEAR BOX
The azimuth gearbox is a low backlash worm gear box. The worm gear drive
isolates any backlash in the motor drive from the system. In addition, since it is
a 40:1 ratio it will not back drive, eliminating any need for a brake on the drive
train. (Fig 3.1)
The motor drives the input worm via a quill/female hole and square key. The
worm shaft is extended with a hex shape installed for the hand crank. The
azimuth capstan is secured to the output shaft with a square key knurl plus
permanent locktite to eliminate any backlash between the capstan and
gearbox.
The low backlash is achieved by selective fit of the worm and worm gear. The
nominal backlash for the gearbox is 30' which is reduced by the
Roto-Lok® drive to less than 4' of the beam of the antenna. The gearbox
contains synthetic oil filled half way to the level plugs. Because of the design
capacity of the gearbox, low rpm and limited cycles experienced by an SNG
system, no maintenance is required.
3.3 AZIMUTH MOTOR
The azimuth drive motor is a 24 DC motor with integral 30:1 spur
gear train. (Fig 3.2.) The motor armature rotates at up to 3000 rpm
causing a high frequency noise that will vary depending of the loading
condition of the motor.
The maximum output speed is 100 rpm. The output shaft is “D”
shaped with a special adapter with a slot for a square key.
Since the low backlash worm gear drive isolates the backlash from
the motor, any backlash between the shaft adapter, square key or
motor gear train will not be seen by the reflector boresight. The motor
is mounted to an adapter plate that is bolted to gearbox with (4)
screws.
No maintenance of the azimuth motor is required.
Figure 3.1
Figure 3.2
