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Anonymous Poster

Is it possible using small AC motor carries 60Kg load?

10/25/2007 4:42 AM

How can I reduce load torque (load = 60Kg) that able to be carried by a AC small Gear motor 90W (motor rated torque = 1.5 N.m)?

Is it possible?

Thank You.

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Guru
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#1

Re: Is it possible using small AC motor carries 60Kg load?

10/25/2007 4:58 AM

The solution is gearing.

The http://en.wikipedia.org/wiki/Post_Office_Tower has a rotating section that was, until the building's closure to unauthorised persons, used as a public restaurant. A toroidal-shaped secion of the building weighing many tonnes was shifted, according to folklore, by a relatively small motor (1hp-ish?) producing a speed of around 1 rotation every 22 minutes.

There is a similar thing in place in the CN Tower in Toronto.

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#2

Re: Is it possible using small AC motor carries 60Kg load?

10/25/2007 6:04 AM

You cannt reduce torque. its conservation.

you can reduce speed by enlarge shift of motor radius. at least let

60x9.8xr = 1.5x100xR; r=Rx 0.25cm choice >40cm and load radius <10cm

so you get gear ratio and speed ratio is

n1/n2 =1/4

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#3
In reply to #2

Re: Is it possible using small AC motor carries 60Kg load?

10/25/2007 9:40 PM

none find there is a error at the answer?

enlarge shift radus of motor should be insteaded of enlarge load shift radius.

otherwise the motor cannt move the load. Im sorry for my error.

I shall post a pic to correct later.

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#5
In reply to #3

Re: Is it possible using small AC motor carries 60Kg load?

10/25/2007 10:44 PM

oh, it is.

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Guru

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#4

Re: Is it possible using small AC motor carries 60Kg load?

10/25/2007 10:29 PM

Torque is directly proportional to KW and inversely to RPM.Lower the rpm higher the torque.U have not mentioned the out put rpm of the geared motor.

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#6
In reply to #4

Re: Is it possible using small AC motor carries 60Kg load?

10/25/2007 11:15 PM

you are right. p= torque x omiga or simple n.

but poster has nt required that how much n he will get.

Achimedes said give me a fulcrum. I can title the earth.

in fact its imporssible for him to do it. it will take him ages and ages.

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#7

Re: Is it possible using small AC motor carries 60Kg load?

10/26/2007 11:36 AM

With the acceleration of gravity at 9.8 m/s2, 60kg is approximately 590N. 590N/1.5N.m =392/m, which means that you would need an ideal gear ratio of 392/(the radius of the wheel or drum doing the lifting). I'm assuming a cable being wound up onto a drum to exert the force - if that is the case, the effective radius of the drum is the actual drum radius plus the radius of the cable. If the drum has an effective radius of 0.1 m, then the ideal gear ratio would be 39.2. If the effective drum radius can be reduced to 0.025 m (diameter 50 mm), then the ideal gear ratio drops to 9.8.

Ideal gear ratio implies no friction and no safety margin, so something on the order of a 20:1 gear ratio should do it (with the load carried on a Ø 50mm drum). The built-in gears of the gearmotor were presumably already taken into account when specifying its torque output, so this is an additional 20:1 gear ratio, which of course means a 20:1 speed reduction from the output shaft RPM.

A 20:1 ratio is easily obtained by a single worm gear, and a worm gear of that ratio has the additional advantage of being able to support the load in the event that the motor loses power or otherwise fails.

You specified an AC gearmotor. all the small AC gearmotors I've ever seen were not reversible unless they had an external capacitor with access to leads to allow direction switching, so if you are lifting a weight and need to lower it, you need to be able to switch directions.

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#8

Re: Is it possible using small AC motor carries 60Kg load?

10/26/2007 4:14 PM

Do you want to lift the load , or move on conveyors horizontly , i have seen grinders weighing some 130 kgs rotated by AC 220V 50Hz 100w motor through pulleys , or sugarcane crushers were motor1800 Rpm is reduced to crushing drums 20 rpm with same watt motor , you can lift the load of 60 kgs vertically with 90 W AC motor through gear assembly

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