Fig 4.8 page 38 question...
 

What does the " = 627 = " at the bottom of the page near the front frame mean. I never noticed this before!!:confused:

Ah glad to see that you have read the book not just looked at the pictures. Write down the dims from the drawings then write down the dims from the text, then tell me what you notice?

Sorry I'm in work (no book) I know the front frame should be 630 mm at the top I just wondered why this dimension has changed and what the "=" signs mean.

Placing = signs either side of a dimension is a generally accepted method of saying its equal about the centerline.

as above
the distence across the centerline so you half it and that is the distence from the end to the centerline