I am currently in the process of designing an engine dynamometer for a small engine. Maximum power of 1 KW @ 7000 RPM and a maximum torque of 1.6 Nm @ 5500 RPM. Here is my proposed method, but I have some concerns that I'll state below: Prony Brake Essentially a friction dyno, I would probably affix a disk brake to the engine drive shaft with a set of brake calipers to apply the braking load (friction force) to the shaft. My main question is, how would I attach the torque arm so that the braking load is thus transferred to the arm which presses downward on a load cell? Here is an example of what I would like to follow: What I'm having trouble seeing is how the torque arm is attached so that it will capture that braking load. In theory what I would need to do, is to apply friction the shaft via the brake pads, to some arbitrary RPM I would like to measure the torque and power at. Once I have the RPM and the load cell readout, calculating torque and power is simple. Here is the standard prony brake setup: What they are doing here is trying to balance the moment arm by adding weight as friction is applied to the shaft. Essentially the same principal as having the moment arm contact a load cell, only the moment arm would be 180 degrees apart and trying to rotate down onto the load sensor. I do like this setup, but I figured it was more practical for shafts that aren't rotating in the several thousands of RPMs. So I wanted to look into the brake caliper idea as seen in the first image. As you can see here though, as you tighten the nuts down, you are essentially creating a clamping force on the shaft thereby slowing the shaft down. I hope I've made my question clear and have not confused anyone, if I still need to clarify, feel free to post and ask some more questions. Main Question: I don't understand how they have the moment arm attached in the first picture so that the braking force that the caliper applies to the brake disk is transferred to the arm which then presses down onto the load cell at a given RPM. It looks to be able to pivot on the shaft. If anyone else has any alternatives to this idea, feel free to post them.