Hello, Friends:
New to armor modeling and new to the forum. Here's the first of what will likely be many "stupid" questions from a new guy.
For my first kit I chose Dragon's Sd.Kfz.250/1. Of the kits at my LHS it seemed to be both simple enough for a first-timer and still an interesting subject to hold interest. As you know, the Dragon instructions are high on visual but LOW on textual support (I'm coming from the world of HO craftsman structure kits, where the instructions make up an entire book).
I'm told that the key to making Dragon's "Magic Tracks" sag appropriately is to not glue the idler arms until ready to install the tracks, allowing you to adjust for tension. SO...what's the idler arm? Not being very mechanical, I'm looking at the instructions for the wheels and looking for a part that looks most likely to be the one that would adjust for slackage. Thanks, again, from a real neophyte.
Kruisyk in Chicago

Hi David,
First welcome aboard !

The idler arm is the extreme arm of a running gear supporting the idler wheel i.e. the one coming without teeth on it also named drive sprocket or simply sprocket.

Olivier

The idler is the last weheel within the tracks - the one at the back that doesn't quite reach the ground. It's used on real vehicles to adjust track tension (compensating for wear) by being shifted backward or forward as needed. On the kit, the arm will be the bit of plastic (probably cranked - I've not seen one) that connects the wheel to the hull. It may be possible to adjust its position slightly by displacing it from the recommended position, using the hull end as the pivot point. If the attachment point is circular, this is easy; if it's not, you may need to file off some corners. I wouldn't recommend the alternative of splitting the arm, as that will introduce a weak point.

You may even be lucky enough to have an idler arm that builds like the real thing, which would allow you to move it slightly back or forth (rather than in an arc) and give better adjustment.



The sprocket is the toothed wheel at the other end of the track run - the one that transfers power into the tracks. Don't confuse the two! These terms will become second nature to you soon and you'll find yourself wondering why cartoonists can't depict tanks accurately when it's so bleedin' obvious ...

Thanks, gentlemen. That should help.
kruisyk

Sorry if my English generated confusion I meant the idler is not the toothed wheel this one being named sprocket.
Concerning the position of the idler and sprocket it all depends on the running gear architecture. On the Merkavas for instance the sprocket is at the front unlike most of other tanks.

Olivier