reversing an alternating current motor..

Hello all,
Go easy on me, I'm not an engineer ;)
I googled this and couldn't find a definitive answer. I have an AC motor/gearbox that I want to use to drive a pulley system. The motor takes
110-15volts AC.
How does one reverse an AC motor? Is it as simple as DC where you can just reverse the polarity, and just insert a reversing DPDT switch in there?
Thanks,
Tim
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No. There are lots of different types of motor which work on AC, and only some are reversible. You'll need to give more details of the motor... Does it have a commutator, brushes, and windings on the armature (i.e. a universal motor)? These are reversible but some are not designed for it and won't work well. Does it have an external capacitor? These are reversible. Does it have a couple of thick single turn coils wrapped around the field winding core (shaded pole synchronous motor)? These are not reversible.
Might also help if you said what the motor was originally designed for (e.g. something which required a synchronous motor) and what nameplate information there is on it.
--
Andrew Gabriel

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I figured it wouldn't be that easy ;)
I'm going to have to disassemble the thing and examine it a bit. I found it at a surplus store so there isn't much information on it.
Tim
writes:

takes
just
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takes
just
Not only is the motor an issue. Some gear boxes are designed for load in one direction only.
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| Go easy on me, I'm not an engineer ;)
In this newsgroup? They don't do that here ;)
| I googled this and couldn't find a definitive answer. I have an AC | motor/gearbox that I want to use to drive a pulley system. The motor takes | 110-15volts AC. | | How does one reverse an AC motor? Is it as simple as DC where you can just | reverse the polarity, and just insert a reversing DPDT switch in there?
It depends on the type of motor. All theoretical motor designs can be reversed by some means. Some motors may be designed with a particular direction in mind and not fuunction properly if reversed. Some may require switching the wires on the actual windings which may not be easy to do. Others, like a three phase syncronous motor, can generally be reversed fairly easily (assuming no direct dependencies in the design).
--
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| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
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takes
that 115 volts indicates it would be a single phase motor, and that means it is either a universal motor or a capacitor-start motor.
If it is a universal motor which does not have a capacitor, but rather has a board with a capacitance simulator, can't help you. It can be done, but you need to know where to put the switch leads on the board.
If it is a motor that uses a physical capacitor (little round can or disk) - there are three basic parts in the cap start motor - the rotor (moving/rotating electromagnet), the stator (fixed electromagnet), and the capacitor (it shifts the incoming amps in one of the magnets so as to cause the magnets to start out of phase, rather than lock up in opposition). The motor runs because the magnets are made to be a little out of phase when it starts, and it keeps running because the rotor momentum keeps the phases just a little off. Which way it shifts on start establishes which way it rotates. So you make the rotor magnet lag, it rotates one way. You make the stator magnet lag, it rotates the other way.
I have reversed single phase motors by switching one of the leads of the capacitor, so as to change which magnet "leads" the other when the magnets build a field. E.g., if it is on the rotor lead(s), move it to the stator lead(s). It has been a while since I have done it personally (Once I showed the shop, now they do it as required).
I think I moved the capacitor lead from the rotor wire to the stator wire -
Note: If the gearbox has a uni-directional overrun brake, it won't go in reverse. Those brakes are fairly special and rare, however.

just
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Post whats written on the motor nameplate
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