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gnitseretni
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[*] posted on 20-9-2016 at 15:20
Electrical help?


I want to make a square tubing roller to roll arches for driveway gates. I can get a discarded gate operator for free(click link to see pic below). It has a 24V DC motor attached to the gearbox. It doesn't anything about amps or watts on the motor.

How can I power the motor? I know nothing about electricity. If possible I'd like to power it by plugging it into a regular 110v AC outlet instead of hauling around two heavy car batteries. And also if possible, I'd like to be able to reverse direction of the motor.

Any ideas?

https://www.dropbox.com/s/y8gv08jnxwafhsp/KIMG0128.jpg?dl=0
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Sulaiman
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[*] posted on 20-9-2016 at 15:54


you could use a 2P2W switch to select polarity/direction
http://www.instructables.com/id/HOW-TO%3a-Wire-a-DPDT-rocker...
and a simple switch on the supply or motor side for off/on.

A 24 Vac transformer output with a bridge rectifier and no capacitor works well to drive dc motors.




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gnitseretni
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[*] posted on 20-9-2016 at 17:23


Thanks.

I've looked around for 24 Vac transformers. They don't say anything about bridge rectifiers or capacitors. How do I know which one I'm looking at? Also, should I look for one with a specific rating, even though I don't know the amps or watts for the motor? I've googled and a lot of gate operators use around a 1HP motor.
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zwt
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[*] posted on 20-9-2016 at 18:16


Quote: Originally posted by gnitseretni  
I've looked around for 24 Vac transformers. They don't say anything about bridge rectifiers or capacitors.

A transformer converts one AC voltage to another AC voltage. A rectifier is a separate component that converts AC to DC. You need both, or a power supply which contains both.
Quote:
Also, should I look for one with a specific rating, even though I don't know the amps or watts for the motor? I've googled and a lot of gate operators use around a 1HP motor.
Yes. Your power supply will need to be rated to supply at least as much current as you motor might use. 1 horsepower = 750 watts, 750 watts / 24 V = 31.25 amps. So, assuming the motor is 1 horsepower, you'll need a 24VDC power supply rated to supply at least 32 amps.

There are 24V battery chargers with current ratings in that ballpark: this one, rated for 24V 30A, might power your motor, if it's just under 1 horsepower (or less).

[Edited on 21-9-2016 by zwt]
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gnitseretni
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[*] posted on 20-9-2016 at 18:59


I think I left out some key information: I'm trying to stay as low cost as possible. I don't need to keep the 24V DC motor if that's what makes it expensive to power it. The ability to reverse the direction would be nice but not at all required. Maybe the cheapest solution is to simply find a decent AC motor and find a way to get it to drive the gearbox.
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[*] posted on 20-9-2016 at 23:45


Find an old washing machine !

The motor is relatively powerful, but you'll also need to do some gearing to get enough force to bend square steel section.




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[*] posted on 21-9-2016 at 01:45


for their size, d.c. motors are more powerful than induction motors,
so if you fit an induction motor to do the same work, it will be larger.

You can power a 24 V motor with 12 Vdc (e.g. automobile oltage), it will run 1/2-speed.

I suggest that you buy a cheap digital multimeter
e.g. http://www.ebay.co.uk/itm/HOT-NEW-LCD-DIGITAL-VOLTMETER-AMME...
Useful for checking batteries, fuses, filament lamps ......

Looking at the motor I doubt that it needs 32 A
and with no load on the motor/gearbox probably a few amperes only, easy to measure with the above DMM on 10A range.
Using one or two 12V batteries you can determine the power of your d.c. supply required....
most likely a cheap battery charger will do.




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[*] posted on 21-9-2016 at 04:58


The pic you have given looks like two gear boxes. Is the actual motor not visible?

If so look at the actual motor it may it may have a name plate with details on it. You may be able to contact the manufactures or find a spec for a similar motor.

As its already been suggested the power requirements of the motor depends on its mechanical load. So it will depend on how much torque is required to bend your tubing and how quickly. However most gate drives tend to be geared to slow speeds so most of the power may be going into the gear box and motor losses. It may have a clutch thats slips when the torque gets too high. Was it driving a factory gate or a house gate?

As already suggested try out the motor that you have already with a 12V car battery (jumper leads to your car battery), ideally while bending tubing.

DC motors are available for operation on rectified mains voltages so if you can find one that is mechanically identical to yours it will simplify your problem.

Repurposed washing machine motors are free of cause and many these day are DC (rectified mains) which makes reversing and speed control simple. But the mounting and coupling to the shaft can be difficult.


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gnitseretni
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[*] posted on 21-9-2016 at 14:33


Yeah there's two gearboxes in the picture. The motor is attached to the gearbox on the left. You can see a tiny bit of the motor.

I have a 12V battery charger but it's only rated for 10A. I'll hook it up tomorrow and see what it does.
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[*] posted on 21-9-2016 at 15:03


I'm guessing something like this would work fine?

http://www.ebay.com/itm/24VDC-21A-Deltron-Single-Output-Swit...
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