Girth gear

1. A girth gear formed by a plurality of gear segments which are adapted to be secured together in an end to end arrangement to form the girth gear, each gear segment comprising:

a rim, and a web extending from a central region of an underside of the rim; and

at least two flanges at each end of the gear segment for joining each gear segment together when the gear segments are in an end to end arrangement, each of the two flanges being positioned on either side of the web;

wherein at each end of each gear segment each flange has a first side secured to or formed integrally with the rim, and a second side most adjacent to the web spaced therefrom such that a gap is provided between each flange and the web.

2. The girth gear according to claim 1 , wherein an end face of each end of the gear segment lies in a radial plane of the assembled girth gear, wherein the end face comprises an end of the rim and the outwardly facing surface of the flange.

3. The girth gear according to claim 1 , wherein the end face of each end of the gear segment is in a plane which is parallel to an angle of the teeth on the rim, wherein the end face comprises an end of the rim and the outwardly facing surface of the flange.

4. The girth gear according to claim 1 , wherein each flange has a plurality of holes therethrough whereupon assembly of the girth gear the plurality of holes are aligned with a plurality of holes in the flange of an adjoining gear segment, each set of aligned holes can then receive a fastener for securing gear segments together.

5. The girth gear according to claim 1 , wherein each end of the gear segment is of a planar configuration comprising an end face of the rim, an end face of the web and an end face of each of the two flanges.

6. A gear segment for forming a girth gear, the gear segment comprising: at least two flanges secured at each end of the gear segment, the at least two flanges are adapted to co-operate with a flange on another gear segment for joining the gear segments together, wherein at each end of each gear segment each flange has a first side fixed to or integrally formed with a rim of the gear segment, and wherein at each end of each gear segment a web is spaced from the at least one flange such that a gap is defined between the web and each flange such that the flange is not fixed to the web, wherein the web extends from a central portion of a concave underside of the rim.

7. The gear segment according to claim 6 further comprising stiffening means to stiffen the assembled girth gear, the stiffening means being provided by one or more gussets, wherein the one or more gussets are positioned to extend between the web and the rim or the at least one flange and the rim.

8. A girth gear formed by a plurality of gear segments which are adapted to be secured together in an end to end arrangement to form the girth gear, each gear segment comprises:

a rim, and a web extending from a central portion of a concave underside of the rim; and

at least one flange at each end of the gear segment for joining each gear segment together when the gear segments are in an end to end arrangement,

the at least one flange having a first side extending substantially in an axial direction of the girth gear and a second side, closest to the web and extending substantially in a radial direction of the girth gear, wherein the first side is secured to the rim and the second side is spaced from the web.