Loco Frame - Truck Gearing

Re: Loco Frame - Truck Gearing

Postby sd80mac » Tue Jul 12, 2016 5:40 pm

gerhard_k wrote:In the GP7 thread, just a few days ago, both you and Brian mentioned the 14:1 ratio as being generally used. As we all know, with model locomotives, the problem is seldom inadequate speed but rather sufficient low-speed smoothness and control. So while your design is still fluid, you might consider a 14- or maybe even a 16-tooth gear, even if it will need smaller teeth to fit in TT. After all, how often will one of your engines want to be MU'd with another different engine, so that the absolute speed similarity will be important?


I think I can design a 16:1 gear train. And I'm with you in thinking that this ratio will put the final locomotive speed right where we would like it. Let me see what I can put together over the next couple of days...

Donnell
sd80mac
 
Posts: 138
Joined: Mon Sep 27, 2010 4:55 am

Re: Loco Frame - Truck Gearing

Postby sd80mac » Wed Jul 13, 2016 3:50 am

Here is a rough draft of the 16:1 gear train for a TT Blomberg truck. I uses two different sizes and three styles of gears, a 16-tooth axle gear, a 16-tooth spur gear, and a 23-tooth spur. These are drawn as module 0.3 gears.

The black circles represent the pitch diameter, and the red circles represent the 40" wheel diameter.

Image
sd80mac
 
Posts: 138
Joined: Mon Sep 27, 2010 4:55 am

Re: Loco Frame - Truck Gearing

Postby ConnRiver » Wed Jul 13, 2016 6:36 am

Just caught up with this thread. I'm about to tackle the GP7 power chassis, and while a couple years ago I read a ton about gears and gearing, I'm gonna have to review carefully before I tackle the drive train.

Hope we can all work through this together, for our mutual benefit. Sure counting on you guys, I know, for my own enlightenment.

Donnell, I've got this DLP SLP 3D printer almost finished here (mine has an MDF structure, not LEGO.) Would be nice if it could make acceptable spur and axle gear patterns. (Click on 'Show All Items' and check out the T-Rex skull.)

http://www.instructables.com/id/Chimera ... d-printer/

In the GP7 Project thread, Bernd listed URLs for a couple of sites that could be good sources of gears, too. Gotta check those out in detail.
Brian Chapman
Cedar Rapids, Iowa / USA
ConnRiver
 
Posts: 421
Joined: Tue Sep 15, 2009 10:51 am
Location: Cedar Rapids, Iowa / USA

Re: Loco Frame - Truck Gearing

Postby krokodil » Wed Jul 13, 2016 10:47 am

[quote="sd80mac"]Here is a rough draft of the 16:1 gear train for a TT Blomberg truck. I uses two different sizes and three styles of gears, a 16-tooth axle gear, a 16-tooth spur gear, and a 23-tooth spur. These are drawn as module 0.3 gears.




Hi there is something wrong with the calculation. The pitchdiameter of gears is D=MxT

Eg. A gear with 20 teeth has a pitch diameter of 20x0.3=6 mm, or with 19 teeth it will be 19x0.3=5,7 mm
Greetings from Austria
E.T.
User avatar
krokodil
 
Posts: 384
Joined: Tue Jan 29, 2013 6:46 pm

Re: Loco Frame - Truck Gearing

Postby sd80mac » Wed Jul 13, 2016 6:34 pm

krokodil wrote:
sd80mac wrote:Here is a rough draft of the 16:1 gear train for a TT Blomberg truck. I uses two different sizes and three styles of gears, a 16-tooth axle gear, a 16-tooth spur gear, and a 23-tooth spur. These are drawn as module 0.3 gears.





Hi there is something wrong with the calculation. The pitchdiameter of gears is D=MxT

Eg. A gear with 20 teeth has a pitch diameter of 20x0.3=6 mm, or with 19 teeth it will be 19x0.3=5,7 mm


That is the formula that I used, and if you look at the OD measurement of the center 16-tooth spur gear you'll see that it's right on.

Diametral pitch = 0.3 x 16 = 4.8mm

The other measurements are distances between gear centers.

Donnell
sd80mac
 
Posts: 138
Joined: Mon Sep 27, 2010 4:55 am

Re: Loco Frame - Truck Gearing

Postby krokodil » Thu Jul 14, 2016 5:44 am

Sorry the many 9s in distances confused me. :-)
Greetings from Austria
E.T.
User avatar
krokodil
 
Posts: 384
Joined: Tue Jan 29, 2013 6:46 pm

Re: Loco Frame - Truck Gearing

Postby sd80mac » Thu Jul 14, 2016 10:01 am

krokodil wrote:Sorry the many 9s in distances confused me. :-)


No problem. And thanks for checking the drawing. You encouraged me go back and verify that what I did was correct! :thumbup:

Donnell
sd80mac
 
Posts: 138
Joined: Mon Sep 27, 2010 4:55 am

Re: Loco Frame - Truck Gearing

Postby krokodil » Thu Jul 14, 2016 2:38 pm

I do not know exactly how the upper part of the drive mechanism will be solved, but I prefer the worm in the middle of the gear mechanism ( symmetrical drive ).
Greetings from Austria
E.T.
User avatar
krokodil
 
Posts: 384
Joined: Tue Jan 29, 2013 6:46 pm

Re: Loco Frame - Truck Gearing

Postby sd80mac » Sat Jul 16, 2016 1:48 pm

Here is a rendering of the gearbox for a 9ft wheelbase Blomberg truck. There's still a lot to add, but at least it gives you an idea of where I'm going with the design.

Donnell

Image
Image
Image
Image
Image
sd80mac
 
Posts: 138
Joined: Mon Sep 27, 2010 4:55 am

Re: Loco Frame - Truck Gearing

Postby krokodil » Sat Jul 16, 2016 2:09 pm

Hi Donnell

Nice design but take care for the first gear from the worm (upper right on the last picture). The worm gear usually has tilted teeth (fitting the worm), while the spur gears have usually straigth teeth. ( in higher modul numbers - 0,4 or 0,5 it is less important, at modul 0.3 can be tricky). Either you have to use a very narrow wheel for this stage, or you have to use step gear with bigger diameter for worm and smaller for the rest. There is one more option, you can tilt the worm - you have to test it.
Greetings from Austria
E.T.
User avatar
krokodil
 
Posts: 384
Joined: Tue Jan 29, 2013 6:46 pm

PreviousNext

Return to Prototypes / Models

Who is online

Users browsing this forum: No registered users and 1 guest