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twin roller dyno

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Hi , i have a question , i have seen from the tutorials that when making a run the car climbs the load sensing roller , are the front and rear rollers linked to maintain inertia or does it solely run the front roller with the rear just coasting.

Loving the courses learning loads .

cheers Keith

Hi Woody, Not 100% sure, but if a twin roller dyno, with strap point between the rollers (the kind meant for climbing) isn't linked, it would not be able to measure correctly for the reason you mentioned. It is technically possible if they measures rpm of both rollers, but it is far easier to link them. Another thing to consider is the sudden acceleration of the idle roller at the end of a ramp run... Older twin roller dynos may not be linked. I recently got hold of an old rusty unlinked twin roller, and the speed measurement seems to use rpm of the idle roller (no tire slip). The power calculation seems to use the rpm of the roller with retarder. I guess it was made made for the requirements back in the days. The power gauge maxes out at 150kW :)

Hi Helge , thats what i thought , i have already bought a set of gears and a big toothed belt to join them together somehow , i think this has got to be the right way as it will keep the inertia constant on the load cell , i do get erratic / spurious readings sometimes on the torque and bhp readings but only on the calculated flywheel readings , i have a set of oldish clayton rollers and a Sportdevices SP5 DAQ set up , but after watching this course i really want to upgrade to a mainline sometime soon.

cheers Keith