The design of the trestle aimed at the possibility of rotating the parabolic trough about a single axis automatically (east-west or north-south) and about the second axis manually. The possibility of the manual tracking allows the reduction of the IAM (incident angle modifier) by positioning the para­bolic trough with the ideal angle to the sun, especially during the experimental phase.

As identifiable in Fig. 2, the trestle is built up of a frame base of square steel bars with the dimen­sions of 2 m x 2 m, which gives the construction the necessary stability. In the middle of the frame base, a vertical square bar is fixed. With a bearing at the top, the vertical square bar holds the car­rier for the collector body. The whole construction is mounted on concrete blocks to stabilize it and to avoid slipping. Its weight is about 60 kg without the concrete blocks. The main disadvantages of the trestle are the vast dimensions, the high mounting expenditure, the high material usage and the restricted possibility to build several parabolic troughs in a row.

As mentioned above, the collectors’ rotation axis is equal to its caustic line, which means that the trough rotates about the absorber system. For this reason the absorber always remains in a fix posi­tion, so that the inlet and outlet pipes can be assembled inflexible.

The bearing of the trough comprises of a combination of a fixed bearing at the bottom and a loose one at the top. They are mounted with the carrier, so that the trough rotates between the carriers’

blades. The absorber system is inserted into the trough from the outside by sliding it through the fixed bearing, which is designed with an appropriate opening. The absorber system is positioned between the bearings on a cushion to protect the sensitive glass pipe.

If several parabolic troughs are arranged in a row it is not possible to change the absorber system of one trough in the middle of the row in the case of damage. That is a big disadvantage in view to the handling since it would be necessary to remove several parabolic troughs to change one ab­sorber.

Planned optimization: It must be possible to arrange several collectors in a row. For this reason the possibility of a manual tracking about a second axis will be relinquished, so that automatic tracking will be feasible only about one axis (east-west or north-south). In a north-south arrange­ment angles of rotation of 160°, respectively in an east-west arrangement of 80°, will be necessary.

Between two collectors in the row, there will be only one post, at which both collectors are fixed from each side. To reduce costs, the 1 m high post will be designed of standardized steel I-section, which is zinc coated.

The bearing concept will be assembled of seven components which will meet the following de­mands: bearing of the collector (static and dynamic load), support of the absorber system, transfer­ence of torsion moments from one collector to the next collector in a row and compensation of lin­ear thermal expansions to avoid restraints. In addition, the bearing must balance the draft of the collector body (see above) to make a rotation about its axis possible. Mainly because of the last mentioned reason, there is no product on the market which meets the mentioned demands. Because of this it is necessary to develop a new concept.

To compensate the above mentioned side plates’ draft of 4°, all components are screwed on ac­cording slant mounting plates, which are also screwed on both side plates of the collector. The bearing itself consist of a bearing-seat, in which a sliding bearing is forced. Due to the open inner diameter of 65 mm, the connecting pipes of the absorber system fit through this opening. The rota­tion of the collector will be around a hollow shaft, which sticks in the sliding bearing and will si­multaneously be used as a support for the absorber system. The hollow shaft is designed with a flange, so that it remains in its fixed position by screwing it at the post. To transfer the torsion moment, the slant mounting plates are connected by stiffening components between the collectors.