RC Tank gearbox CG transmission by Iliya Cerjak

Build it yourself Heavy Duty Tank transmission for use in radio controlled tanks & other tracked vehicles.



3D CAD data and/or 2D production drawings now available upon request



CG3 Double Differential Tank steering system 

3 speed forward & 3 speed reverse tank gearbox for vehicles up to 150kg




The CG3 is a universal heavy duty tank gearbox design incorporating most requirements I gathered over the past few years from many RC big scale tank enthusiasts around the world. The double differential steering system enables very smooth and controlled steering, in which the power of the inner track is transferred (regenerated) to the outer track when steering. (See this page for more on the subject). An electric motor ( for example a cordless drill ) with an ESC is all you need for steering. The narrow design enables it to be placed in the narrower space in lower hulls of for example 1:6 scale Tigers, Panthers and Panzers.


Three speeds are available both in forward and reverse, shifting on the move is possible which mimics the surge movement of a real tank during gear shifts. The gear ratios of the box itself are respectively 1:50 , 1:30 , 1:18 . The output shafts are fitted with sprockets and chains, so one can easily choose and/or adjust the desired ratio by using different sprockets. For calculating the required sprockets for your design use the CG3 Calculator. (Don’t hesitate to contact me if you need help with the calculations on your drive line).  The input can be fitted with sprockets and chain, so the engine, clutch and chain parts of mini-bikes can be used. The gearbox is fitted with steel gears throughout. The metric spur gears module 1, are readily available at any gear supplier ( for example RS-components , www.hpcgears.com , www.qtcgears.com or www.transdev.co.uk ).

Shifting of the three gears is accomplished by one servo, the forward-neutral-reverse by the second. The neutral enables easier IC Engine starting, revving an IC engine whilst stationary and is easier for transporting the vehicle without engine power. The gearbox can be powered by either an electric motor or an IC Engine.

Below some examples of the many possible different configurations.


(Click on picture to see larger image)


Image2       Image4

IC Engine sidewinder input.                                                   IC Engine Inline input.


Image3       Image5

Electric motor sidewinder input.                                          Electric motor Inline input.




The design pack is available in pdf and step upon request. The pdf-pack contains a detailed partslist, a comprehensive assembly drawing and all production drawings. The step contains all parts in 3D. Both are available upon request. All my efforts are for free, donations are very welcome!



Preview of the assembly drawing.                                                                         Completed CG ( See feedback page for more details)


< Go back to main page