Motor choice for low speed, low torque series application
Motor choice for low speed, low torque series application
(OP)
I am looking at converting my drill (soybean and wheat planter) to hydraulic drives to allow for variable rate and clutching; it is currently ground driven. 30' of drill will be divided into 4 - 7.5' sections, which will be automatically controlled.
System design as follows:
Now the question: I'm trying to pick out the best motors for the application. I have been looking mainly at Char-Lynn because of ease of availability. A T series (spool valve, geroler) with the slow speed valving option sounds good,but I don't see that I'd be running the recommended 300 psi difference between A and case pressure - I don't know how critical that is with such a low load. A 2000 series (disc valve, geroler) would be another option - the application charts show lower flows and speeds than the spool valve designs. Does a disc or spool valve tend to handle low speeds better and does one inherently tend to leak less than the other?
Thanks for your time, Casey
System design as follows:
- Monitor supplies PWM signal for rate control and 12V output for each section control (uses radar and RTK corrected GPS for speed input and application control)
- Brand EFC proportional valve
- 5 motors in series:
- Idler motor constantly running a shaft sensor (360 pulses/rev) - nil torque requirement
- 4 motors to turn the seed meter shafts, each with a solenoid valve plumbed to bypass to provide clutching for the section - 30 in-lbs of torque on each of these
Now the question: I'm trying to pick out the best motors for the application. I have been looking mainly at Char-Lynn because of ease of availability. A T series (spool valve, geroler) with the slow speed valving option sounds good,but I don't see that I'd be running the recommended 300 psi difference between A and case pressure - I don't know how critical that is with such a low load. A 2000 series (disc valve, geroler) would be another option - the application charts show lower flows and speeds than the spool valve designs. Does a disc or spool valve tend to handle low speeds better and does one inherently tend to leak less than the other?
Thanks for your time, Casey
Talk To Other Members
RE: Motor choice for low speed, low torque series application
1) Generally speaking the disc valve motors are better (smoother) at low speeds than the spool valve motors. However, at such a low torque requirement there may not be too much difference.
2) At such a low pressure, leakage shouldn't be an issue with either motor.
3) The 300 psi minimum pressure requirement is to avoid the possibility of cavitation if the motor overruns (since the low speed valving option uses narrower slots in the spool valve).
4) The 2000 series motor will probably cost you 40 - 50% more than the T series.
RE: Motor choice for low speed, low torque series application
Ted
RE: Motor choice for low speed, low torque series application
RE: Motor choice for low speed, low torque series application
Hey man.. we get oily too. Some of us. Sometimes.
Seriously though, glad you sorted things out. Few forces are as good at problem solving as a farmer on a deadline.