Contemplating a Panzer IV build? Then...

[Max-U52]

You mean directly in front of the idler, how that piece is lower than the others, which are all in line with the top of the attachment point cover for the bogeys? If so, I see what you mean and I wonder if that's because it's the last one before the idler? Maybe to prevent track binding between the last roadwheel and the idler or something?

[43rdRecceReg]

You mean directly in front of the idler, how that piece is lower than the others, which are all in line with the top of the attachment point cover for the bogeys? If so, I see what you mean and I wonder if that's because it's the last one before the idler? Maybe to prevent track binding between the last roadwheel and the idler or something?

Hmmm.., Gary, Arnie raises an interesting issue. I think I've vaguely noticed that the bump stops weren't perfectly aligned, but assumed it was a kind of engineering illusion. I expect on severe terrain the final bogey could tilt up and possibly make contact with last return roller or the track it's supporting..that's with the perfectly aligned scenario, of course. Otherwise it might be to do with the internal arrangement of suspension components, relative to the position of the engine.

This blueprint shows more clearly what we have missed (including Tamiya, but not eagle- eyed Arnie )

Panzer IV ausf J blueprint

Click to enlarge...
As you can see, the final return roller is quite low, and if the leaf suspension in the final bogey were fully compressed and the final wheel tilted fully up, it would come pretty close to the roller. Even more so, if the bump stop were positioned higher (and aligned with the others), and thus allowed greater travel. the deck floor is also bevelled upwards at that point, and maybe this is connected with the anomaly.
The mystery deepens.....

[Max-U52]

I think I see it, now if I can say it. The last stop is also the only stop behind a bogey. The rear wheel on each bogey from the front back has it's upward travel limited by the roadwheel directly behind it. You can only push the track so far upwards before the front wheel on the bogey behind stops the upward movement of the track and also the rear wheel on the bogey in front of it. On all but the very last bogey. With no bogey behind, and therefore no front roadwheel behind it, the last roadwheel needs a stop that the wheels in front of it don't. Did that make any sense?

[sassgrunt]

I was wrong about the standoffs; Roy had it absolutely right. However, regarding the 'bump stop' behind the last bogie unit, the Tamiya kit has one in the right place. Look at the picture on page 6 of this thread - the one with the Panther roadwheels displayed in front of the Panzer IV - and you can clearly see it.

[43rdRecceReg]

I was wrong about the standoffs; Roy had it absolutely right. However, regarding the 'bump stop' behind the last bogie unit, the Tamiya kit has one in the right place. Look at the picture on page 6 of this thread - the one with the Panther roadwheels displayed in front of the Panzer IV - and you can clearly see it.

Thanks, Mike. As luck would have it, the spacers designed for the model ('hex step spacer'..in Tamiya- speak) happened to be included in the suspension arm bag I'd bought; that's how I could try various options out. I also have many bags of brass, plastic, and steel standoffs from my frantic PC building days. None were quite suitable without grinding, drilling....and precise measurements, so..
You've a keen eye; but then maybe you don't need glasses quite as thick as mine. Maybe you're blessed, and don't need them at all. Anyway, having just had a closer look at the model;..eureka! you're absolutely right: the rearmost bump stop is slightly lower than the others. Scaled down to 1/16, it's not as immediately apparent as it is on the full-size Pz IV Arnie snapped; but the more I look, the clearer it is. Hmm... well, top marks to Mr Tamiya once more, and to you too
The whole track setup on the very last iteration of the Pz IV; the one with only three return rollers, has little symmetry in it (Top and bottom tracks are not parallel) so it's even harder to judge what's in line and what isn't.

Your reasoning sounds about spot on, Gary. Given your experience recently with those pesky Hetzer tracks; with all that lateral thinking, and engineering improv., I'll always bow to your experience in these matters, you hippy wizard

[Arnie_DK]

Huh. Whadayaknow. Sasgrunt is right. Tamiya actually did include this detail. Not as low as on the real thing, but its definetly there.

I Checked all my pictures from Munster to make sure it wasnt a one off thing and on every picture I have of their tanks with a Panzer IV build up, have the last bump stopper in that low position.

And I agree that it is most likey to stop the last road wheel making contact with the idler.

[43rdRecceReg]

Huh. Whadayaknow. Sasgrunt is right. Tamiya actually did include this detail. Not as low as on the real thing, but its definetly there.

I Checked all my pictures from Munster to make sure it wasnt a one off thing and on every picture I have of their tanks with a Panzer IV build up, have the last bump stopper in that low position.

And I agree that it is most likey to stop the last road wheel making contact with the idler.

Yep, he is. It occurs to me now,though, having thought it over that tanks go forward, in the main (unless you go with the old joke about Italian tanks... ). That's why, from a physical point of the view, the lead bogey makes contact with bumps first, and needs
some form of limiter, apart from that provided by its partner wheel. However, when the tank goes in reverse, the last wheel in the series will make contact first with any obstructions, and that's why it needs its own bump s top...to prevent the tank 'diving' at the rear. Just a thought..

[43rdRecceReg]

For the benefit of those who may be new to all of this (armour lunacy!), the unit highlighted is further evidence that Tamiya do their homework properly when it comes to tank proportions and details..especially here on the Panzer IV.
It's also evidence of Sassgrunt's observational skills

Tamiya's Panzer IV rear bump stop accurate positioning

[sassgrunt]

The observation had more to do with luck than skill, I'm afraid. However, one of the benefits of a discussion like this on suspension travel is how it relates to other tanks. It always bothered me that on the Elefant, the last bogie unit seemed to be installed backwards, (in that the knee joint is at the rear, unlike the other two units it follows). But when you talked about the vehicle travelling in reverse and encountering obstructions; it makes to have built it that way. Thank you for clearing that up for me! -Mike

[43rdRecceReg]

Just discovered another wee anomaly. I'm surprised I didn't notice it when comparing model cupolas earlier: the Tamiya ausf. J cupola is considerably larger than the HL/Taigen F2 version.
I suppose this could be an issue of relative scale interpretation between HL and Tamiya. However, i found that their respective upper hulls had the same dimensions. Or, it could be that the Ausf. J had a larger cupola than earlier models. Some Pz IV buff ( ) here will probably know, so I'll forgo the research.
The more involved I get with models of this WW2 workhorse tank, the more I wish it had a dedicated Alan Hamby style 'Information centre' website, as per his highly rated one for the Tiger ( http://www.alanhamby.com/tiger.html... for the benefit of newbies). Info is out there, sure, but not collated conveniently in this way.

Cupola size comparison between HL-Taigen and Tamiya

I perched the Tamiya cupola on top of the (temporary) HL turret, as it sat on the Tamiya superstructure. The more I looked to admire my handiwork, the bigger the cupola grew! It even looks a tad large for the Tamiya hull it tops.
I can only imagine, then, that the Tamiya turret is also correspondingly slightly larger than Taigen/HL F2/G/H variants. If not, it's all going to look a little unbalanced.