Bridges have always and understandably so, been a popular subject for Meccano models, this model is based on the Beam Bridge model 7.15 from the 1938 7-8 instruction manual also published post war 1945-1950.  (The original instructions I used are shown below.) I thought it would be a nice model to show off the attraction of the 1930's blue and gold coloured parts that I think really suit this model well. The bridge is quite a good but simple representation of this type of bridge. CLICK IMAGES TO ENLARGE
Construction information I followed the form of the original model but used many additional parts beyond those listed in the original plan to enhance the appearance of the bridge particularly the additional of two p/n 99 braced girders on the lifting beam.  I added a pair of extra vertical support frames, cross beams between the upright frames and many extra cross braces. This gave the model a more solid apperance. I found problems with the hand operated lifting operations. There were two solutions needed one was from a version of the bridge shown on the NZ Meccano website built some years back by Keith Way. In this the drive mechanism was moved from the bridge deck, giving a better mesh of the gears. The second was getting the balance finely tuned, just a few grams either way made the raising either freeze or enabled to move up or down. There is no mention in the original instructions of adding weight inside the boiler probably not enough left over parts in the Number 8 outfit! On mine the boiler is filled with M4 nuts and bolts, I have thousands of these.One useful fix was to use a tri flat rod to secure the 3” pulley on the lifting shaft “A”. Click the YouTube logo to see the model in operation Here is another lifting bridge I built with outfit 10 Page created July 29 2020 Revised September 16 2021
Beam Bridge 1938 7-8 page from instruction manual