Transmissions

[Aero 9000]

Originally Posted by scalelover

Even with these pics you can see its nearly impossible to have an interior, especially in a day cab. I really dont even see a way in a conventional or an extended sleeper without figuring out a way to lay it on its side.

--Dan

I will have to say having a interior was not a priority when designing this transmission. For me personally it is not a priority at all. I don't see the need to make the cab comfortable for a 5 inch hight plastic man. The cab interior is far better utilised for equiptment. If cab interiors are a priority it may be more suitable to build a static model.

The transmission connot be laid on its side. It contains automatic transmission fluid. It would make a awfull mess, not to mention oil up the motor......

[sparkycuda]

One difference between 1:1 and our equipment is the prime mover RPM. Diesel engines have a very narrow power band and low max RPM, requiring multi-gears to match available power/torque and road speed. Our electric motors have a considerably wider RPM range, depending on turns, etc. I chose a low RPM 85t motor for my Payhauler. It turns 5200 RPM at 7.4V, so is about double the diesel engine RPM in the real truck. By using a 3-spd trans, I just about replicate prototypical road speed, since the 1:1 had a 6-spd trans. Lower turn motors spin a lot more RPM, reducing the actual need for a many-gear trans - use of one speed or a 2-spd trans works just fine since we seldom see anything like scale speed (70 MPH) with our trucks.

But then, nothing beats shiftin' those cogs 9 times going across the room! To each his own - just have fun doin' it.

Ken

[Espeefan]

Impressive, but totally overkill. I like it! None the less, I just don't see any need for 9 gears. Three seems about right, and when I had a 3 speed truck, I found myself most often running in 2nd gear. It was a good in between gear. Now my latest truck has a really simple one speed planetary gear head motor and that doesn't bother me one bit. It's more compact, stronger, and can handle all kind of torque. Yes, I gave up shifting the gears, but that's one less thing to worry about, it frees up a channel on my radio, and I just never found myself shifting gears all that much anyway. It's fun for a little while, but if your driving your truck in a tight place, about the only place you do get up to top speed is in an open parking lot. Unless you've got some aux. gear reduction.

I wonder how much backlash that 9 speed has. Tamiya's 3 speeds have way to much.

[Aero 9000]

Originally Posted by Espeefan

Impressive, but totally overkill. I like it! None the less, I just don't see any need for 9 gears. Three seems about right, and when I had a 3 speed truck, I found myself most often running in 2nd gear. It was a good in between gear. Now my latest truck has a really simple one speed planetary gear head motor and that doesn't bother me one bit. It's more compact, stronger, and can handle all kind of torque. Yes, I gave up shifting the gears, but that's one less thing to worry about, it frees up a channel on my radio, and I just never found myself shifting gears all that much anyway. It's fun for a little while, but if your driving your truck in a tight place, about the only place you do get up to top speed is in an open parking lot. Unless you've got some aux. gear reduction.

I wonder how much backlash that 9 speed has. Tamiya's 3 speeds have way to much.

With metal gears and synchronizers backlash can be dramatically reduced because the slots in the gears and the drive dogs on the sychronisers are cut into a solid blank and can be made any size.

The plastic gears and sychronisers Tamiya use are injection molded and cross sections of injection molded items must be kept thin or the plastic will shrink considerably when it cools. Therfore the drive dogs on the synchronizers are narrow and the slots in the gears are wide (the land in between the slots is narrow). Resulting in lots of backlash....

[Aero 9000]

I am working on a Cat V8 engine cover to go over the front of the transmission to improve the engine bay looks.

This is the extension through the front firewall into the engine bay with the 9 speed moved forward.

[Aero 9000]

Here is the gear ratio chart for anyone interested.