| 摘要 |
An inner cylindrical tube (12) centred with the geometrical vertical axis is closed by a bottom plate (17) at its lower end (16). At its upper edge (18), the tube has a radially inwardly directed ring-shaped flange (19). An outer tube (14) encloses the inner and at its upper edge (21) has a radially inwardly directed ring-shaped flange (22) with which it rests rotatable on the flange of the inner tube via an intermediate bearing (24, 25). The two flanges limit an inspection aperture at the tops of the two tubes. An assembly plate (27) fits releasably on the outer tube flange and over the inspection aperture. The upper side of this plate supports the aerial, whilst its lower side, in conjunction with the inner tube and bottom plate limits a closed space accommodating the motor (28) fixed to the bottom plate. A gearwheel (32) is rigidly connected to the lower side of the assembly plate and centred with the geometrical vertical axis, and a second wheel (31) is coupled to the motor drive shaft. The two gearwheels mesh in order to rotate the outer tube in relation to the inner. |
