Doughty Valley 2019 a USA view
 

https://youtu.be/qH2YC-QNca0

Russ

Pity about all the safety barriers getting in the way and yellow jackets bossing folk around along with all the notices about hot surfaces and moving parts.............

Notable that those air brakes cannot be screwed down to increase the load , and all the engines are running on the governors ( as American engines do the whole time )

They are purely for putting a load on the engine. Invented by A D Baker for testing his production engines before dispatch. Known as Baker fans.

Most shows in US have several Proney brakes for determining HP etc.
Some electric but mostly friction brakes.

Yes indeed , Fodens used something similar to test run their wagons , known in the works as The Flip Flap .
My point was that they cannot be screwed down to overload .

Provided the engine is governed. Power consumption on a fan actually goes up as the cube of the rpm.

A very good point though, and they can still make an engine bark - which is really the only thing that Joe Public might understand.

Martin