ETS-Lindgren 2175 Antenna Tower - Manual (Page 8)

8 | Introduction
The antenna carrier is raised and lowered by a fractional horsepower, electric,
variable speed motor. A worm-type gearbox driven by the motor provides the
adequate torque needed to raise and lower the carrier and prevents the carrier
from back-driving the motor. The motor and associated electronics are contained
in a shielded enclosure mounted beneath the platform of the unit. Under
command of the controller, the motor typically positions the carrier within
one centimeter of the desired location. To prevent over travel of the carrier in
either direction of movement, the mast system has integral fiber optic limits. Soft
limits may be set within the travel range provided by the mechanical limits using
the controller.
The motor base is connected to the controller through a twin fiber optic cable
assembly. This fiber optic cable transmits both directional control and position
information. Power to the motor base is provided locally to the motor through a
detachable, grounded power cable.
A carrier brake is mounted on the carrier assembly. In the event that the carrier is
released from the rope suspension, a spring-loaded cam locks the brake into
position against the mast and locks the carrier so that further vertical movement
is restricted.
The carrier brake is intended to provide some protection to the
carrier and the antenna; it is not a fail-safe brake for protection
to personnel. Personnel operating this equipment should be
instructed to stay clear of the carrier and boom at all times
whether or not the carrier is moving.
Polypropylene braided rope guy lines are provided for installations requiring the
mast to be guyed and must be firmly anchored for vertical stability. Use of the
guy lines is recommended in all applications to provide maximum stability.
Standard Configuration
• Motor, 220 VAC, nominal
• Input frequency 50 or 60 Hz
• Tower platform casters for movement of the unit
• Offset antenna mount
• Stinger antenna mount
• 10-meter fiber optic control cable for inside chamber