Is there information as to the construction and installation of the clock in the tower of the Helsinki train station ? Thank you.

Very little information about the clock could be found in books or in the internet. In the book Högström Hilkka: Helsingin rautatieasema - Helsinki railway station (ISBN 951-53-0533-0) is the following chapter:

"The Siemens-Schuckert electrical company installed the German clockwork for the Helsinki Railway Station tower. Originally the weights had to be cranked up daily by hand. The dial was made by a Finnish workshop (Oy Arvo Urho). In the 1930's, an electric rewinding apparatus was installed, and in 1980 the clock was coupled with a quart-controlled central mechanism.
...Over the years, travellers have liked to bet on the tower's dimensions. Its height from street level is 48.5 metres. The diameter of the dial is 3.3 metres; the minute hand is one and a half metres long and weighs 60 kilos, the hour hand is one metre long and weighs 40 kilos."

The right place for you to contact when you come to Finland would be Helsinki City Archives (see
http://www.hel.fi/tietokeskus/ ). The address is Eläintarhantie 3 F, 00530 Helsinki. (Information and researcher service open Monday to Friday, 8.15am-4pm.) I hope they can help you with your inquiry.