Electrical Lift For 20kg Load For 30m Height

Consider the output of the motor to be the maximum rate of increase in potential energy of the load. The maximum speed that the load can rise is the maximum wattage of the motor divided by the weight of the load and divided by acceleration due to gravity, which here comes out at <....tap...tap...tap....press equals...> 1.9ms^-1.

It would be good to under-speed so that the motor isn't overtaxed and also to allow for the masses and friction in the lifting mechanism. Go for, say 1ms^-1 maximum lift speed, perhaps, and design the pulley system to suit. So it's going to take no less than 30sec to complete the lift.

Once the design is complete, do run the proposal past the insurance company's Engineer/Surveyor for the purposes of bringing the equipment inside the facility's collapse liability insurance policy before construction starts.

Do you're own homework!

I guess some people need a personal teachers. Maybe I should do that as a part time job!

Come on, Ivan! How can these kids get anywhere, if we don't do their homework?

To the OP: (1) if this is not homework, that is one thing, why do you leave out key specification of how fast this thing has to work?

(2) If this homework, you should learn to press your own calculator buttons.

Work≠Power

Rate of work = Power

you're ≠ your !

You have no way of knowing whether this is homework or not, and the OP did NOT ask for an answer; he/she asked for guidance. To me, there is a BIG difference!

vjpassion: Welcome to CR4, and ignore the negatives. I believe the guidance has already been provided, so I won't add more. If you need more guidance, come back and give a few more details.

Do note that a 20 kg mass/weight lifted 30 m is a dangerous object if it should fall. It should be lifted inside some kind of enclosure that prevents human access during the lifting, or at absolute minimum some signage indicating possible danger. Also, the lifting assembly MUST have some mechanism to prevent rapid falling in the case of loss of electrical power.

An enclosure ? Gee your no fun, I could imagine you at a piniata party. Don't swing that bat Jimmy ! Here use this toothpick,,

You are woefully ill-equipped to design anything

Your total lack of understanding of the task is telling.

You must be a student, so do some research on mechanical engineering lifting systems.

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Don't expect an anonymous forum to do your work for you.

Is there actually a web forum where a person can go to and ask this kind of question and someone will figure everything out for you ? Cause I'd like to know it, I got a whole sheet load of questions I want answers for.

A Website that can process consultation fees might help.

Yahoo Answers has an engineering section under Science and Mathematics.

Get a vehicle winch.

Bazzer

NO NO NO!

This is an academic exercise for probably secondary school! (hopefully not university)

This is a basic exercise in Work, energy, force, moment arms, etc.

The weight is so light no one would use a winch. At 20kg you could use a sash cord.

Get a light vehicle winch!

Bazzer

Carrying the exercise further.

Assume winding drum has 0.5 metre circumference. Motor speed 3600 rpm.

Drum revs = 2 rps.

Motor revs = 60 rps.

Gearing ratio = 60/2 =30.

One cannot make those assumptions.

Agreeing with PWSlack!

Why use a 3600 RPM motor? ...the number 3600 implies an AC motor, when the OP specified running on battery power.

0.5 hp=375 Watts, or 375 Nm/s. Take away a little for friction and a safety margin, and you have around 300 Nm/s of usable power.

20 kg weighs a bit over 196 Newtons.

Ignoring the extra force required to start the motion, the maximum lifting speed is ≈300/196 ≈1.5 m/s, so the 1 m/s you chose is reasonable.

The OP specified 0.5" rope. If all the rope were wound in a single layer, your 0.5 m circumference drum would require 60 turns to lift the weight 30 m, so the drum would have to be at least 30" long. I suspect that a narrower drum would be preferred, but not necessarily. Of course a narrower drum would require more layers and have a larger diameter...