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My Sherman
Posted: Mon Aug 17, 2009 7:33 pm
by Robert E Morey
Posted: Mon Aug 17, 2009 7:46 pm
by Stewart Ashton
Posted: Mon Aug 17, 2009 10:43 pm
by Adrian Harris
Good to see your Sherman return to the forum
I hate to be the one to point it out but the tracks should be on the other way round, with the links "smiling" at the front.
Adrian.
Posted: Mon Aug 17, 2009 11:41 pm
by Derek Attree
Hi Bob
That is a cool sherman .
Derek
Posted: Tue Aug 18, 2009 7:52 pm
by Robert E Morey
Thanks guys, yes the Sherm has been neglected far too long. After running the Panther I can hardly wait to get this one rolling. Thanks for the correction on the track Adrian, will get that fixed!
Bob
Posted: Thu Aug 20, 2009 8:49 am
by Kent Wiik
Hi Bob
Good to see your Sherman getting the attention he deserves again.
Many years ago (the days before the Panther era...) I noticed your work on the Sherman.
Stunning craftsmanship that took building to a new level.
I think you were the first one putting cast letter/numbers on the tank.
Will follow your build with interest.
Man I love your workshop and all those machines...
Keep up the good work!
/Kent
Posted: Sat Aug 22, 2009 11:40 pm
by Allan Richards
Bob,
Nice lloking Sherman, I like the detail you have done on the suspension guides. You will find when you get it running that it is much more bouncy than the Tigers and Panthers but once you get the tracks set up they run very well.
Posted: Wed Aug 26, 2009 4:11 am
by Tim Bowman
Hi Bob
As others have said, nice to see your Sherman back under way. Looks super and gives me that "Sherman envy" feeling.
keep up the great work
Tim
Posted: Thu Sep 03, 2009 9:51 pm
by Robert E Morey
Posted: Thu Sep 03, 2009 10:55 pm
by Adrian Harris
Good to see another Sherman tearing up the dirt
> the Sherm does not have the climbing power or traction (with identical motor power)
I
think that the Panther was supplied with higher ratio gears in the motors, in which case it's worse than you suspected as that should give the Sherman more torque than the Panther
Have you seen the picture in my gallery of my Sherman climbing my ramps
The Sherman track treads are a lot more robust than the Panther or Tiger ones but you can bend the return roller brackets and support springs if you get a stone trapped in there.
My motors for the prototype arrived today from Parvalux but they've omitted to drill and tap the mounting feet so I have to either dismantle them myself and do the work or send them back - likely to be quite a considerable expense given their weight
Adrian.
Posted: Thu Sep 03, 2009 11:33 pm
by Robert E Morey
Hi Adrian,
The Sherm seems to have more trouble in loose stuff than the Panther. Maybe too much torque is the problem. It does just sit-n-spin sometimes. The narrower track will dig in instead of float like a wide track, making the problem worse.
I agree your super steep ramp test is something all right.
Any ideas on how to limit the bogey wheels getting pushed back? Other than the obvious, don't drive it over severe bumps. The Shermy doesn't like even a 1" height difference on my wood ramps, whereas the Panther will handle this no prob. I'd like to make some kind of stop to keep one wheel from folding back on the other. It doesn't appear to cause any permanent damage, but it looks painful. Like turning your foot around backwards on your ankle!
All the same I still like it and am glad I got one!
B
Posted: Thu Sep 03, 2009 11:41 pm
by Adrian Harris
> Any ideas on how to limit the bogey wheels getting pushed back?
When I first read that I though you meant they were getting pushed up and not returning.
Are you saying they are following the track backwards and bending back under the bogie keep ?
If they can do that then I would have thought it likely that your track was much too loose. It should be tight enough to "ring" if struck with a metal object. None of this flapping around like on the German cats
Adrian.
Posted: Fri Sep 04, 2009 4:02 am
by Robert E Morey
Adrian,
The arms are returning fine when pushed up. In fact I'm really pleased with the slide pad modification I did and the addition of two keeper screws to keep the volute springs centered as the suspension arms move up and down. These mods have worked very well.
The issue is the bogey wheels occasionally knuckling under as shown in my hack photo. The suspension arm pivots down so far the first wheel contacts the second wheel in the set. Crossing a gulley or over a root (anything that completely unloads the volute springs) can allow this to occur.
I'm a little hesistant to tighten the tracks too tight as this will prematurely stretch the links and wear the pins even faster. It will also make the whole system less able to tolerate any debris, dirt or rocks on the links. I think you are correct though, that more tension would reduce the tendancy to pivot under.
Seems like some kind of a stop or limit would be better?
I wonder if the real tanks had this problem?
I will see if I can get a little more track tension now that the links are broken in a bit.
Forgot to ask previous - didn't the proto have working motors? Or perhaps they got ruined in the rain? Thats an aweful thought - shame on someone.

Posted: Fri Sep 04, 2009 7:20 am
by Adrian Harris
> I'm a little hesistant to tighten the tracks too tight as this will prematurely stretch the links and wear the pins even faster.
I can understand your reluctance but I do think you'll find the tank runs better with tighter tracks. I also found it stopped the tracks sticking to the sprockets and being dragged upwards in front of the first road wheel.
The M4A3 instructions for track tension says to tighten the tracks until there is 1/2 to 3/4 of an inch clearance between the track and a straightedge lying between the centre and rear support rollers. That's a maximum of 1/8" in our scale
> It will also make the whole system less able to tolerate any debris, dirt or rocks on the links.
Given the solid track tread and idler construction, I found my Sherman tended to crush most thing which got into the tracks
> Seems like some kind of a stop or limit would be better?
The only way I can see of doing that would be to run a length of threaded rod through the volute spring and into a tapped hole in the top of the bogie housing. You would have to have some slack under the radius arm though, in order to allow it some movement.
> I wonder if the real tanks had this problem?
There's certainly lots of photos of crews putting the tracks back on
> didn't the proto have working motors?
Like all good maintenance crews, they were removed before the tank was abandoned.
> Or perhaps they got ruined in the rain?
The turret traverse and gun elevation motors were both still in the tank when I collected it and, apart from a mild dusting of oxide, both motors are still fully operational
Adrian.
Posted: Fri Sep 04, 2009 8:39 pm
by Allan Richards
Robert,
Don't be afraid to tighten the tracks up because all you will do is to compress the suspension a little which is what you want to do to prevent the bogie tucking under. Run the model a little more to bed the tracks in, as I found mine slackened quite a bit initially, then adjust them to be tight an you will find the problem goes away.
As for climbing ability my Sherman has plenty of power but lacs the grip to climb as well as my Tiger. It is also a lot more bouncy than the Sherman, which I think was a problem with the full size tanks. This said they are great runners.