Q&A Forum
Hi I am about ready to calibrate and commission my dyno, I'm using a Stuska xs-111 brake with a 100kg load cell. I understand the principle of calibrating it ie: zero then add weight on an arm to simulate load.
I need to fabricate an arm to enable me to do this but I'm unsure on the best way to achieve this. the main question I have been considering is if the arm needs to be balanced or if there is a way to compensate for the weight of the arm before the calibration weight is applied.
I would be grateful if anyone could point me in the right direction with this
Hi,
There are a few ways to do this. The process is to zero calibrate it with no load, then load calibrate it, the press Save. The problem is normally to figure out what load is applied to the load cell when you have an calibration arm which has a certain weigh and a calibration weight at a certain distance from the brake center.
The easiest is to think in terms of torque. What torque does the calibration weight and load arm apply, and then calculate what that means in kg or lbs for the load cell. For the load arm you should mark the center of gravity (i.e. where it balances on a sharp edge) and measure the distance from the middle of the brake to this COG. The effect of the arm on the torque is the weight of the arm * distance to the COG.
There is an easier way though if you find it hard to calculate the effect of the arm:
- Do a zero cal with the arm attached
- Hang the load and do a load cal. The load cell weight = calibration weight * calibration arm length / load cell arm length (i.e. the weight of the calibration arm is not included)
- Click save
- Remove the arm and click Zero cal again
- Click save
Hi
That's a great help and as simple as I could have hoped it could be I have made an arm that allows me to hang a weight at up to 3 times the load arm length.
Stuska standard arm load cell positions are at 160 mm and 320mm so I have made an arm that allows me to hang the weight at 480mm and 960mm. I have a 20kg weight and I am using a 100kg load cell at the moment so I figured that 3 times the length would be equivalent of 60kg at the load cell.
As I understand the instructions if I'm using the shorter arm length then I would attach the arm then zero the calibration enter the arm length as 480mm and the weight as 20kg, save this then remove the weight and arm, zero again again then save this as the calibration.
please correct me if I've got that wrong anywhere
regards
steve
As I understand the instructions if I'm using the shorter arm length then I would attach the arm then zero the calibration enter the arm length as 480mm and the weight as 20kg, save this then remove the weight and arm, zero again again then save this as the calibration.
That is correct. Either enter 48cm and 20kg, or enter 16cm and 60kg. The latter is more in line with the text on the screen ("Torque arm length to load cell"), but the result is the same.
That's great thank you I can get that done now
regards
steve