Do you have the Serial Number for this machine?
If this is like the machines sold in the USA the "parking brake" is actually two pins on either side of the machine that when safety levers are raised the pins engage in hole in the center sprocket in the chain box on either side of the machine. Some times you have to creep the machine one way or the other to let the pins pop into the holes. Same when trying to move after levers are down a gentile nudge one way another to take pressure off the pins.
This is the image of what the system I'm familiar with looks like but there are other versions used in other parts of the world, one even shows a disk brake that is mounted on the front axles.
You could also look at this site to see if any thing there looks like your machine:
Case IH Parts Catalog Lookup. Buy Case IH Parts Online & Save!
www.messicks.com