On Saturday 26 December 2020 13:36:18 andy pugh wrote: > On Sat, 26 Dec 2020 at 16:49, Gene Heskett <ghesk...@shentel.net> wrote: > > Two additional questions. That 70 ohm 300 watt braking resistor just > > walked up and rang my doorbell, so are you using one? > > I am not using one. It would be useful if I was, since I added > on-the-fly gearshifting to the two speed box.
These spindles don't come with a gearbox. Plain old motors. > The idea is that if it is in low gear and the spindle speed goes above > 500 rpm then it disconnects the low-speed clutch and slows the motor > down to the right speed to operate the high-speed clutch. > Unfortunately the spindle slows faster than the motor, so they only > really catch each other at zero-zero. > > If I had a braking resistor then I could slow the motor faster, and > there would be more chance of catching the gear change. > > But the VFD is next to the motor, behind a panel that is only > accessible once the lathe is pulled away from the wall. > So I have not tried to add one. > > Downshifting goes a little better. > > I drive an old fire engine that has the same problem, if you are going > up a steep hill, that the vehicle could climb in top or third gear, if > you have to stop and go into first, there is no way to get out of > first and you have to hold it to the top of the hill. No synchros in that gearbox? I'd be getting quotes to replace it with one that did. Racers use an ignition killer for upshifts, leaning on the synchro rings kills the ignition until the rings are unloaded as the shift is completed. Mopar trannys from about 1932 have a different internal motion and are amenable to that in both directions, lean on the lever to downshift, tap the kill for long enough to unload the gears, the ignition comes back on and as the rpms build the synchro finishes the shift. An upshift is done the same way but the ignition isn't re-enabled until the shift is completed. Clutch pedal not required for either. Those boxes weren't really rated for the hemi v8's so gear life isn't great usually breaking second gear idling along in 5 o-clock traffic, but never when I was busy showing the Chevies how its done. I did 140k miles in a 52 Chrysler Saratoga all on the same transmission case. That car was the best concealed weapon ever in the stoplight grand prix once its m6 tranny and fluid drive were replaced with a 53 dodge od tranny. That made the effective rear end gear 2.42/1. 30 mph per 1000 rpms in high overdrive, it could go the length of South Dakota at 3300 rpm in about 4 hours, on one 21 gallon tank of gas, getting 21+ mpg doing it. I knew a few tricks with those old carter carbs too. Even with a 10 foot 2.5" straight pipe exiting under the rear axle it never got the laws attention. It could do anything I wanted it do except turn a corner. That hemi was simply too heavy, 1100 lbs hanging on a hoist. Lots of cast iron in that puppy. > -- > atp > "A motorcycle is a bicycle with a pandemonium attachment and is > designed for the especial use of mechanical geniuses, daredevils and > lunatics." > — George Fitch, Atlanta Constitution Newspaper, 1912 > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
