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Issues with Hydraulic Brake

(@hansl)
Member

I'm experiencing an issue with my brake staying on after I have used the "Manual" brake mode to control rpm.  When I uncheck the apply brake box and say, slow down or come to a stop on the drum, and then take off again, sometimes the brake will be locked on at 100%.  I can tell this as the dyno builds hydraulic pressure, but the brake output gauge is showing 0% brake.  The only way to get the brake off when this happens is to either reset the system, or go to the options screen and run the brake on and off with the slider.  Sometimes if I move the brake control drop down tab to "off", the brake will release.  I'm not getting any sticking of the brake when only using the "brake sweep" mode to do runs, and it is working well otherwise.  I am using 0-5 volt output, controlling a Sun Hydraulics XMD driver, which then gives a PWM signal to the hydraulic flow control.

Has anyone else seen this?

Another issue I am having is that in manual mode, the ramp up time on the brake is very slow. (you can see this on the brake % and is slowly applies brake)  The issue this causes is that the engine will easily over rev until the PID has time to stabilize.  Once it is stabilized after the initial overshoot, it is working well, and you can adjust very accurately and steadily with the up and down keys.  Works great.  I noticed that when I'm doing "brake sweep" runs, the brake reacts instantly to the set starting brake pressure.  Am I doing something wrong in the manual mode, or is the software just programed to function like this (slow initial brake rise/application)?  I'm always getting at least 1000-1500 overshoot, more depending on how hard you give it throttle.   We can't get it out with any PID adjustments.  I would also note that my team and I are hydraulic system professionals and have extensive experience with PID control, so we know what the adjustments do and how to make a PID stable.

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Topic starter Posted : 12/06/2022 4:40 pm
(@thdyno)
Member

Hi.

Maybe a dump question but i try anyway 🙂 

Why are you using an device that converts from 0-5volt to pwm  when the yourdyno can output pwm signal.

Could it be an issue with the converter.

I think i would try to meassure if the output from yourdyno goes to 0 when you experience the rise in hydraulic pressure.

If the output is 0 then the output from the unit that converts from 0-5v to pwm also should be 0

Hope it makes sence and maybe is helpful

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Posted : 14/06/2022 9:49 pm
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