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  1. bgilbert

    Compact hydraulic seal

    Hi all, I am looking for a low friction and very compact hydraulic seal for low speed shaft rotation. The shaft ID is 60mm, pressure is rather low (1MPa), fluid is synthetic grease. I found something already, that consists in a UHMW-PE ring, energized with an O-ring (Buna). Supplier is...
  2. bgilbert

    Motor selection

    What you want to know first is the amount of torque you need to accelerate your inertia. You want to accelerate very slowly your inertia(within 10-15 min), but the inertia is very large: Torque = Inertia x Speed / Time You have Speed = 524 rad/s (5000 rpm) Time = 600 s (10 min) Therefore...
  3. bgilbert

    Brushless max speed

    Thank you !
  4. bgilbert

    Brushless max speed

    Curt/Brad/all Would you have any suggestion (book, web site...) that would clearly explain the relations between sin/trap/Kt/Kv ? Thanks, Ben
  5. bgilbert

    Brushless max speed

    Here is some new data: I measured the BEMF using peak voltage: Kv = 0.0986 V/(rad/s) Kv is quite different from the measured Kt (0.0847 Nm/A). As Brad1979 stated, Kt=Kv*sqrt(3)/2 for a trap drive and a sin motor. I also verified that the motor is near perfect sinus. Using the formula, I get...
  6. bgilbert

    Brushless max speed

    About the 93% of the drive, I think that I should use 100% instead. That would be because the drive's PWM most likely provides 100% of the voltage, but only 93% of the time. Therefore for the BEMF computations I should use 100%. Does it makes sense ?
  7. bgilbert

    Brushless max speed

    Thak you Curt, Your explanation makes a lot of sense. Still the difference seems high. Would it be correct to state that with a higher torque ripple (using a trap drive and sin motor), the max speed will also be higher ? That would be because the "shoulders" would be higher than the low of...
  8. bgilbert

    Brushless max speed

    Well, Kt was measured by the motor supplier, not using my drive and is 0.0847 Nm/A. Mathematically, Kt=Kv when you use Nm/A for Kt and V/(rad/s) for Kv. You could do the maths, it is not that complicated to demonstrate. On the other hand, I just realised that Kv was also measured by the...
  9. bgilbert

    Brushless max speed

    I need some guidance to understand how to compute the maximum speed of brushless motors. I use a trap drive (Elmo Ocarina 15/60). The bus voltage is 50.8V. The drive is specified to output up to 93% of the bus voltage. I applied the maximum current command on the drive and there is no load on...
  10. bgilbert

    Magnetic properties of SS 416 (B-H)

    OK, I'll try to find the Q&T, but in the mean time, do you have information about the 410 or 416? Where should I look? Thanks
  11. bgilbert

    Magnetic properties of SS 416 (B-H)

    Anyone knows where I can find the B-H curve of the SS 416 ? Thanks!
  12. bgilbert

    Harmonic drive suppliers

    I'm looking for suppliers of harmonic drives. It looks like there is only one supplier out there (HD Systems)... Any hint?
  13. bgilbert

    Bearing Loads

    No.
  14. bgilbert

    Problems with finding a small "high pressure", "Non plastic"

    Bosch's fuel pump provides 26,000 psi of pressure !! and most likely very small flow. I'm also interested in miniature hydraulic pumps. One from hydroleduc is really cool (about 150g weight and about 30mm diameter for the PR20) but I heard is quite pricy (around $2000 ??). Any hint for...

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