A dyno measures torque by using a reaction force through a lever arm.
Understanding Dyno Torque Measurement
Dynomometers, commonly called dynos, are tools used to measure the power and torque output of engines or other rotating equipment. The fundamental principle behind how a dyno measures torque involves the application of a load and measurement of the resulting force. Here is how the process works:
Core Components & Methodology
- Floating Dynamometer: The dyno is designed to float on bearings. This allows the rotating part to move slightly in response to the torque applied by the engine or motor under test.
- Lever Arm: An arm extends from the rotating part of the dyno. This arm is crucial for converting rotational torque into a measurable linear force.
- Force Measurement Device: The end of the lever arm is attached to a device that measures force. This could be:
- Strain gauge: Measures force by detecting the change in electrical resistance of a material under stress.
- Pressure gauge: Measures force by quantifying the pressure applied.
The Measurement Process
- Engine/Motor Applies Torque: The engine or motor drives the rotating part of the dyno. This creates a rotational force called torque.
- Reaction Force & Lever Arm: The dyno resists the rotational force. This resistance creates a reaction force which is exerted through the lever arm.
- Linear Force Measurement: The force measurement device connected to the lever arm registers the linear force generated by the reaction.
- Torque Calculation: The dyno uses the measured linear force and the length of the lever arm to calculate the torque. Torque is calculated as force multiplied by the length of the lever arm (Torque = Force * Distance).
- Shaft Speed Measurement: In addition to torque, a tachometer measures the rotational speed of the shaft. This measurement, combined with the calculated torque, is used to compute horsepower or power output.
Practical Insights
- The accuracy of torque measurement depends on the precision of the force measurement device, and the accurate measurement of the length of the lever arm.
- Different types of dynos, such as inertial dynos, eddy current dynos, or hydraulic dynos, might have slightly different methods for applying the load, but all ultimately use the principle of measuring the reaction force via a lever arm to calculate torque.
Examples
- Chassis dyno: Measures the torque and power output at the wheels.
- Engine dyno: Measures the torque and power output directly from the engine.
Conclusion
In essence, a dyno measures torque by quantifying the reaction force exerted on a lever arm connected to a rotating shaft. This is achieved using a force measuring device and calculations that use the length of the lever arm. The reference confirms that "Generally dynos work by measuring torque via a reaction force through a lever arm"
