water brake load valve issues
i'm having trouble getting my load valve to control the Stuska brake effectively. i've attached a Nema 23 stepper motor to a 1.5" globe valve in a similar fashion to others iv'e seen on here. The valve has aprox 2 & 1/4 turns to fully open
i seem to be having two problems, firstly the stepper seems to lose steps and therefore lose it 0 position and tends to stay open a little and as i'm testing small engines this stops the power run from reaching its max point and i have to reset the 0 point to get it to work again.
The second problem is that the valve appears to be very sudden in its operation, it does very little for the first 5% then the water flow increases quickly for 1 turn of the valve to about 90% flow with the last 10% over the next turn of the valve.
i was thinking of changing to a butterfly type valve to get around these issues, i have a 40mm throttle body from a ford 1.0 ecoboost engine kicking about which i thought could be used with a bit of messing about, does anybody know anything about how to control these throttle housings or would it be best to modify it to be controlled with a stepper motor or is that just barking up the wrong tree and should i persevere with the globe valve?
any help would be appreciated
I run the same setup and had a few of the same struggles as you. I changed the globe valve to have a tapered seat which helped some, the other thing I did was slow the valve down, the stepper motor couldn't move it as fast as I was commanding and it would lose position just as you are describing. So slowing it down actually helped a lot. The last thing is the packing nut on the valve, loosen it until it leaks a little then just tighten by hand until it stops dripping. The packing adds a lot of resistance to the stem of the valve.
The last thing I did was change the stepper to a closed loop stepper with feedback so if it does lose position it will attempt to correct itself, really haven't had any issues with it since these changes and the dyno operates smoothly.
We have valves for sale in the web shop. We spent a lot of development time and money before it worked well. I have a whole stash of stuff that was not good enough. The newest version also includes a proper zero position sensor so you can auto-zero it.
thanks for the replies, I had already tried to slow the stepper down and had loosened off the nut but it still loses the position, i've bit the bullet now and ordered the Yourdyno valve so hopefully then i will have the dyno fully up and running
All of the best for your troubles buddy. Glad to hear you are recovered. THanks!