Sequential 8-speed transmission tunnel with rotary catches and 8-to-1 gearblock




After Eurobricks member @Seasider asked whether the new gearbox parts would allow for a transmission tunnel, the idea sticked with me. So I started designing my first 8-speed gearbox, or in fact 8-speed transmission tunnel. All axles, including the control axles are aligned in a 3x3 tunnel. It has 90-degree limiters for all control axles and a 8<->1 gearblock. To minimize friction, clutch gears are only used for engaging with driving rings, not for transferring drive over axles running at different speed. I think the end result is something special. I used 16t gears to pass control from the main control axle to the secundary control axle. Theoratically knob wheels would have been better, but in practice the 16t gears operate much more smooth and the 90-degree alignment of the control axles is still good.

The gearbox consists of two serial gearboxes. The ratios of the primary gearbox are: 1:1, 5:4, 5:3, 25:12 and the ratios of the secondary (low-high) gearbox are: 1:1, 25:9. Together that makes: 1:1, 5:4, 5:3, 25:12, 25:9, 125:36, 125:27, 625:108, or 1, 1.25, 1.67, 2.08, 2.78, 3.47, 4.63 and 5.79.

The overal in-out ratios can be easily changed though. The primary gearbox and the secondary gearbox are connected with a 16-16 gear mesh in the center of the gearbox. This could be changed to a 20-12 or 12-20 mesh, which would multiply all speed ratios by 20:12 or 12:20 respectively.

Thank you very much @1963maniac for making excellent building instructions for this gearbox.
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Name Sequential 8-speed transmission tunnel with rotary catches and 8-to-1 gearblock
Designer Didumos
Designed 2018
Inventory 195 parts
Theme Technic
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Photo submitted by __I__ at 2019-03-22 19:01:55.285597+00:00
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