Discussing GT6 mechanical power transmission (ie: gears and axles)

I haven’t seen this documented elsewhere, so I thought I’d post here to document what I know about the mechanical power transmission system.

Previously I used GT’s steam fluid and piped power to steam turbines and steam engines, and also GT’s electrical system to transmit EU power to machines. I think axles and gears provide an intermediate power system that’s safer than steam and more consistent.

Mechanical power transmission conducts RU/t (rotary energy). You’ll need to produce it and convert it as needed. Keep in mind that Greg based MP (mechanical power) on his electrical system (EU), and thus you need to keep in mind it can produce and transmit power as packets. EU produces packets, MP uses the term “power”.


  • Axle

Axles transmit RU from one source to one destination. Axles are rated by maximum RU and maximum power packets. Higher quality materials transmit more RU.

Axles are managed by a wrench, and are easily connected and disconnected in place.

  • Gearbox

Gearboxes combine and split power packets across the axles attached to the gear box. Note that it splits packets, NOT total RU. You may have to step down your RU with a transformer to increase the packet count so that you can split it with a gearbox.

Gearboxes have two critical concepts. The first is the concept of an internal axle, which is displayed on opposite sides of the gear box. The monkey wrench is used to specify the side the axle originates from, and will update the opposite face with the other end of the axle. An axle MUST be set for the gearbox to work.

Second you need to have large gears of the same material type in your inventory, and use a wrench to apply those gears to the faces of the gearbox. You’ll want one gear on the axle, and one or more sides to connect to. A minimal configuration is one gear on the axle, and one gear on a single adjacent side to transmit power to.

A gearbox is also the only way to make an axle “bend” or navigate a turn. No power is lost.

  • Transformer Gearbox

Transformer gearboxes have an input face and an output face, and transform input RU and power packets to output RU and power packets by dividing by 4. For example an input of 64 RU/t in 1 packet will output 16 RU/t in 4 packets.

Transformers can be reversed with a monkey wrench to make them combine packets in a 4:1 ratio.

  • Rotation Engine

The rotation engine takes RU from a side and converts it to KU on the face. It’s a 2:1 conversion of RU to KU.

Power Generation:

To have RU to transmit via mechanical power, you must generate power.

  • Steam Turbine

This is typical of early game power. Use a burning box to heat a boiler making steam, and then use a steam turbine to turn the steam into RU/t. Attach that to your axles and now you have power!

Remember using gear boxes you can combine power inputs to make more power.

I recently posted a design making 64 RU/t (16 RU@4 packets) in the creations forum here:

  • Diesel Engines

GT6 now has diesel engines which run off burnable fuel. Once you have oil and other flammable liquids you can add fuel to an engine and it’ll run until the fuel is exhausted. These are very safe and compact compared to steam power.

  • Electric Motor

Later electricity (EU) could be used to make RU. However electrical networks should replace mechanical power.


Doing some more testing.

I have merged the output of 4 Bronze Steam Turbines with Invar innards. Each turbine outputs 32 RU/t, merged into an axle carrying 32 RU/t * 4 power.

The Tachometer shows 128 RU/t, and you can see the splits in this picture. The tachometer than displays total RU (RU * power).


The engine in this rig is 4x Bronze Steam Turbines with Invar blades. Each is fed by 2x Bronze Boilers with joined outputs, heated by Bronze Gas Burning Boxes.

The turbines are joined using Bronze Gear Boxes merged in the middle with gears. The joined axle carries away 128 RU/t (32 * 4).

Removing the axle, the gearing can be seen.


It has been confirmed that using two input power sources on a single gearbox is flakey, but it can’t be fixed. (T configuration)

A single input engine on a gearbox (L configuration) seems to be reliable.