First off great website.A wealth of info.(mostly over my head though. LOL)
I need help figuring what i need to control direction and possibly speed for a 1/2hp 3ph 230/440v AC 40:1 gearmotor im using on a welding fixture.
Its got to rotate left and right. We have 3ph 220/440v power supply. I do know the switch i need needs to return to a neutral or stop the motor upon release of the button. much like a basic chain hoist switch works.
I was thinking if i can control motor rpm i could use a 20:1 gearbox to get thicker teeth and last longer.
Any ways i need suggestions for my shopping list.

 

Reversing rotational direction of a 3 phase motor is just a matter of switching two of the three phases (changing the phase rotation). With that said it becomes a matter of if the motor needs to have a full stop before reversing direction or if the motor can go from one direction to another immediately without a stop? A Google of "3 phase motor reversing relay" will bring up dozens of hits. You choose a relay for reversing (or switch) based on the HP (Horse Power) rating of the motor. Most relays (or switches) used for an application like this also have a mechanical and electrical lockout so only one may be energized at a time. They can also be operated using buttons such as Up/Down, FWD/REV and so on.

Speed is another matter with VFD (Variable Frequency Drive) being popular. Again the VFD is normally chosen by the motor HP rating. A Google of Motor VFD will yield a dozen results.

Both the reversing method and speed control are chosen based on application.

Ron

 

If you incorporate the gearbox mentioned, assuming that you need higher torque, the operational rpm will necessarily be reduced, possibly to a range such that load friction will bring it to a stop when the motor current is de-activated ...placed in neutral.
If the load is not sufficient to stop rotation by itself, then some sort of mechanical or magnetic braking system will be required.

 

If you incorporate the gearbox mentioned, assuming that you need higher torque, the operational rpm will necessarily be reduced, possibly to a range such that load friction will bring it to a stop when the motor current is de-activated ...placed in neutral.
If the load is not sufficient to stop rotation by itself, then some sort of mechanical or magnetic braking system will be required.

It is going to be geared down from gearbox from 40:1 @1750 rpm to around 2 rpm via sprocket and chain drives. I am pretty sure it will stop on its on when circuit is broke.

 

LIke this

 

Many welding fixtures use a DC motor, usually a little cheaper than a VFD for variable motor control.
If you already have the motor then a small VFD may be the way to go.
Many G.B's use worm and pinion, these will not back feed the motor, so overun does not occur.
Max.

 

Then, looking at your post you can take the motor reversing relay route I mentioned but for light duty do a Google of motor reversing drum switch. They can be manually held like holding in a button as they are spring loaded with an OFF center position. Drum Switch or Reversing Relay is pretty much up to you and a drum switch is a simple solution. Grainger, McMaster Carr Supply or any number of industrial supply houses should have either in stock off the shelf.

Ron