8
3.3 AZIMUTH MOTOR
The azimuth drive motor is a 24 DC motor with integral 30:1 spur gear train. (See fig on pg.6) 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 bore sight. The motor is mounted to an
adapter plate that is bolted to the gearbox with (4) screws.
No maintenance of the azimuth motor is required.
The patented azimuth Roto-Lok drive produces a zero backlash; high stiffness, no wear, no lubrication, and
maximum reliability drive system. The system consists of two 1/16, 7x19 stainless steel aircraft control cables
reverse wrapped twice around the grooved capstan and once around the drum, with solid connections on one end
and high force Belleville springs on the other end (Fig. Below). One cable has the capacity to withstand a 75mph
wind load. The additional cable is used to provided increased stiffness and drive redundancy.
If a cable becomes
damaged during usage, cut off cable and continue to use positioner. Replace cable when time permits
at your maintenance facility.
The cables are sized to last the life of the positioner. The springs will automatically compensate for any elongation
of the cable.
Cable position should be checked as per the periodic maintenance schedule in Section 6. If cables have drifted,
manually move cables using blunt instrument on the azimuth drum until the correct position is obtained.
At installation the Belleville springs are collapsed until no “air” is seen between the springs. You should check this
condition yearly to account for the slow settling of the cable strands. Use pliers to hold stud and 1/4 box end
wrench to tighten nut.
Be sure not to over tighten. Tighten until springs are almost fully collapsed. (Fig
below)
3.4 AZIMUTH ROTO-LOK CABLE DRIVE
