this is the standalone viewer and extruder part file. other wise you need the latest version of edrawings to view them
added front and side views this should give you a little more info.
basically the way it works is the tension arms pivot to apply pressure to the hobbed bolt and the camshaft regulates this movement. you could shorten it but you will end up with less movement between the idle rollers and the hobbed bolt, you need to find the sweet spot between enough grip, enough release travel distance to suit your camshaft, using a lager diameter camshaft would make this easier to work out. i used 8mm bolt as camshaft so that gives me 4mm of travel at the camshaft for the tension arms this works out to be about 0.75mm of travel at the idle rollers, this also amplifies the amount of tension that is applied to the filament, if you shorten the height this multiplication is reduced and harder springs will be needed, if you do that the load on the camshaft is also increased, so the sizes that you see there are a compromise of all the factors.