Page Layout ⇒ Horizontal space between number/title for Chapter

[giafro]

Hi
I’m working on a book. I use jurabook which is based on the document class "book". The editor requires that the horizontal space between the number of the chapter, section, etc. and the text of the title is everywhere the same (i.e. 2 cm).
I know that titlesec would be the right tool to use here. However, if I use it I will have to reformate the settings of jurabook.
I have found several macros which fix the space between the number and the text of the title of the Section (and Subsection etc.) which work fine but none for Chapter. Is anyone able to help?

Thank you very much.
Gianni