Thread: C6 Back Gear

I've just finally got working a project I've been working on for a couple of months.
The low speed drive for the C6 lathe originally used a toothed belt drive and an intermediate pulley the give low speeds down to 125 RPM, but after i changed the motor to 3 phase with a VSD I found that the toothed belt was not up to the torque of the motor and would jump teeth regularly under only moderate loads.
I decided after some research to fit an epicyclic gearbox to the new intermediate drive shaft that I installed as part of the motor replacement.
The gearbox has a 4:1 reduction and with the VSD it positively drives the spindle down to very low speeds, the torque limitation now being the final dive belt grip.

For high speed use, the epicyclic gearbox is locked between the ring gear/casing and the planetary gear carrier giving direct drive. The locking is done by the 3-pin carrier being fully engaged in the ring gear housing

For low speed drive, the 3-pin carrier is withdrawn partially to disengage from the planetary carrier but remain engaged in the ring gear housing, and a yoke is inserted into the 3-pin carrier ring to lock the ring gear housing to the lathe frame. This gives the 4:1 reduction in output speed.
The output pulley is part of the planetary gear carrier.

The pictures attached may help with my explanation.

Andrew.
DSCN4399.JPGDSCN0627.JPGDSCN0628.JPGDSCN0831.JPGDSCN0832.JPGDSCN0835.JPGDSCN0834.JPGDSCN0833.JPGDSCN0836.JPGDSCN4396.JPGDSCN4398.JPGDSCN4397.JPGDSCN4400.JPG

That's extraordinary Mahgna, have you tried it out yet, I'd love to see a video of the unit in operation.

I was wondering as to why you'd go to the effort to make a planetary gearbox, now I know. Great work by the way.
Kryn

Thanks Guys.
Attached video of low speed operation in forward and reverse.
Also attached photo of a 72 x 1.25 thread in aluminium done in three passes plus finish pass using the back gear for torque and slow speed.

Andrew.


Back Gear.mp4 DSCN4402.JPG