The drive sprocket includes an interior ring (40), an exterior ring (50), and an intermediate ring (60) situated between the interior ring and the exterior ring.

An intermediate coupling (30) member fits around and engages the inner collar.

The inner ring is fixed to the support structure (11).

Said reduction mechanism comprises a ring gear (30) which includes a fixed outer ring gear part (31) an inner ring gear part (32) bearing inner teeth (33) and shock absorber elements (34).

The inner ring rotates relative to the outer ring in the opposite direction to the outer ring with the first rolling body row and the second rolling body row in between.

The interior ring, exterior ring, and intermediate ring are oriented in a substantially spaced-apart manner, each of the rings have an outer peripheral surface ( 48, 58, 67).

Desirably, side branch expansion forces placed on the inner crown will first cause the inner crown to displace outwardly, then cause the petals to deploy outwardly.

In this state, a space part (S) is formed in an inner rim part (32).

An especially interesting feature of this stadium is the steel frame, which supports the roof cover and includes three parts: the outer ring, the opaque inner ring and the translucent inner ring.

An especially interesting feature in this structure is the metal frame of the stadium that supports the cover which includes three parts: the outer ring, the opaque inner ring and the translucent inner ring.

The linking means (14) comprise an annular ball bearing (18) comprising an inner ring (18a) and an outer ring (18b), one of them being provided with teeth (19).

The clutch has sprags (4) each having engaging faces (4a, 4b) in contact with an inner ring (2) and an outer ring (3), respectively.

The inner crown may further comprise a plurality of outwardly deployable petals.

The inner collar ring (21) is visible through a bull's eye-type glass of the access hole located on the housing side.

A permeable grid electrode (24) surrounds a corona wire (32) and separates an interior corona discharge area (34) from an exterior aerosol charging zone (30).