vacuum cleaner motor reversal?

I have a few duff vacuum cleaners, two of them I've been trying to make one decent one out of, but never completed, and another one which is too far gone to do anything with, anyhoo, I have a lot of vacuum spares knocking about. I'm not too sparkling on electronics, but I remember years ago that our old hoover used to go on 'blow' instead of suck at the flick of a switch, someone told me that if you wire a motor in the opposite way, IE connect live to neutral and netral to live, it spins in the opposite direction, although I've not tried it. My idea is to make a minature blowing machine of some kind, for various jobs and just for pissing about with, so if I reverse the connections around in the motor, will it do as I want and start blowing or will it just blow up? - I'm not too bothered if it does the latter as I've got quite a few, also, do I need to make this connection at the motor end or can I just reverse the wires in the plug?

Or is it a non starter?

TIA

Reply to
Phil L
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In message , Phil L writes

It is, as they say, a total load of bollocks

Reply to
geoff

It hasn't occurred to you that a motor that sucks also blows out of the other end? Isn't it easier to just point the existing exit at whatever you want to blow at?

Reply to
Dave Baker

Never seen one like that (outside of cartoons anyway). On our old cylinder machine you just connected the hose to the opposite end of the machine if you wanted blow instead of suck.

Given that we're on AC now I don't suppose this would make a great deal of difference. If they ever did reverse at the flick of a switch, the switch must have been doing more than swapping live & neutral.

Tim

Reply to
Tim Downie

What does make a universal or induction motor always start and run the same way?

Reply to
Dave Liquorice

Most vacuum cleaners use series wound motors and to reverse those you need to get inside it and reverse the connections to the field windings. Which may not be possible with a sealed design. Other possibility is to reverse the fan on its spindle.

Swapping the plug connections won't do anything - the mains does just this

100 times a second...
Reply to
Dave Plowman (News)

Universal and induction motors are two completly different beasts

universal's are basically a dc motor, direction is hard wired in.

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motors have some sort of start circuit that determines direction
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Reply to
Kevin

Wrong, although if it has brushes with a commutator it's a "universal" (AC/DC) motor and swapping some simple internal connections will do this. Too difficult to explain in ASCII, but I'm sure web searching will turn it up. Purely AC motors won't reverse (for simple levels of fiddling).

Reply to
Andy Dingley

It's AC and is reversing 50 times a second anyway.

You need to reverse the connections to the field coil wrt the armature. The motor might / might not run too well in reverse.

Derek

Reply to
Derek Geldard

My experience with model aeroplane propellors tells me that won't work. ;-) Reversing the motor will.

If the fan is actually a centrifugal compressor that won't work either. Neither will reversing the motor.

Derek

Reply to
Derek Geldard

Wouldnt work. Even if you did contrive to reverse the motor direction, all vacuums use at least a 1 stage, often 2 or 3 stage centrifugal fan which just doesnt work rotated the other way!

Tim.

Reply to
Tim..

Phil L wrote on 17/12/2008 :

Doing that will make nil difference to the direction. Only swapping one of either the field coils or brush connections will change the motors direction.

Even if you get the motor spinning backwards, many of the designs seem to be a semi centrifugal design compressor, so it will probably not make much difference to the air flow direction.

They do already blow, at the opposite end to the end they suck. Could you perhaps modify the output end to accept a pipe?

Reply to
Harry Bloomfield

Dry vac motors are cooled by the inward air blowing over the motor & exhausting around the periphery of the motor. They do 'blow' but through a series of small peripheral vents, so its difficult to channel the airflow - and if its restricted too much it can cause overheat.

Wet/dry vacs discharge air around the periphery or via a tangential tube, depending on the turbine. Tangential discharge motors are usually only found on carpet cleaning machines, but they make excellent blowers.

The top picture here

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is a tangential discharge motor, the second one down is a peripheral discharge.

Reply to
The Medway Handyman

Not in any microwave I've seen. Mine always goes anticlockwise (as do most others I've seen).

Tim

Reply to
Tim Downie

Depends on the type - "synchronous" is just a characteristic of how fast the motor runs, there are several ways to build them. Most of these are fixed to go in one direction (either magnetically by slugging, mechanically with a press-button ('30s clocks), electrically, or switchably) so as to make them reliably self- starting. If it's the simplest sort and really doesn't care, then it needs flick-starting.

Many non-time-critical "synchronous" motors are also not quite synchronous, as they use a little inbuilt slip to give self-starting.

Reply to
Andy Dingley

It's the inbuilt slip, or phase lag, between an induction motor rotor and the stator which gives rise to the restorative force that cases the motor to turn - in effect the rotor is always playing "catch up" with the stator. By definition it is then "synchronous" with the supply, speed control can be achieved by increasing the number of poles/windings but there is an underlying synchronism with the supply frequency in there somewhere. At rest there is maximum phase lag equally in both directions and the forces on the rotor are balanced - a flick will set it going either way as AD says. A capacitor is the normal addition - this forces a small phase lag in one direction when the motor is switched on - it starts to move and the normal forces take over.

Reply to
Bob Mannix

Some had a mechanical means that wound up a kicked the motor in the opposite direction if it started backwards.

Reply to
Dave Liquorice

Sharp microwaves go both ways oh er misses

Reply to
Kevin

So does our Panasonic. First button push, it goes clock wise, start it again and it goes anti clockwise. Never noticed if it changed direct on one run though. I'm usually tending to other cook at that time.

Dave

Reply to
Dave

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