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Need some help... on locating

ljcraft12

Ok I have a project that i wanna put together and I don't wanna say exactly what is but I will try to give as much info as I can... What I am looking for is a small electric motor or motors that can lift about 800lbs. I was looking at maybe using a pair of wheelchair motors with the transmission assembly on them. Although I will need to add a sprocket to them still. I don't think that a direct drive motor will work in what I am attempting to do. Also, I am gonna try to run it off a single wheelchair battery as well but I was looking for a lithium battery that could possibly power them. I will also need a control board that will regulate the speed and power to them and still be able to use a remote control externally wired to the device.

 

So in summary of what I want help with

Does anyone know of a better single motor or pair of motors that will allow me to move about 800lbs and hold it (brake)

What would be the better battery for doing the job.

And a matching board that will contol power flow and speed (programable speed controler I don't want it to go full speed on command at all) for the motor/s and battery.

 

Thanks any help would be apprecitaed

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  • Hello Perry,

     

    You don't give enough information.

    To size the motor and otherwise assist you need to say:

         How fast the load must be lifted (with a suitable gearbox a tiny motor can lift 800lbs, but slowly)

         How far the load must be lifted.

         Do you need precision control of lift distance and/or speed

         How many lifts must the battery be good for

         How many will you build and what is the budget

         How relaible must it be

         Are there any safety implications if it fails

     

    Michael Kellett

  • in reply to michaelkellett

    Ok thanks for reply I will answer them in order

     

    Load does not have to be lifted fast at all I am seriously thinking 3mph might be too much I am thinking more along the lines of 6ft/s is more than adequit enough so I am wanting as small a motor as possible but very reliable.

    2 feet is about the max I want to lift the objects but I actually want them to be rotated as well 360 degrees so I am thinking maybe 1 or 2 motors for the lift and one motor for rotation.

    yes control will be everything I am thinking of proximity switches for the max lift and max bottom or I could do it old school and put switches there which ever would be more reliable.

    I want the battery to be able to lift max load up and down about 40 times so I am thinkning that wont really be a problem at all there.

    Right now I am only buiding one for proof of concept and as far as budget I am hoping not to break the 1,500 mark total but will increase if nessicary for good motor and battery w/chargers.

    Very reliable i want to be able to use this thing everyday if needed or able to sit for 3 weeks if it has to and then run just fine when needed.

    Failure is not the option I am thinkning or so type of external brake function in conjunction with the tranny brake incase that fails.

     

    Thanks Perry Craft

  • in reply to ljcraft12

    Hello,

     

    No we can do some sums:

    800lbs = 400kg

    6ft = 2m

    2 feet = 1m

    (these are good engineering approximations  - the = sign in this replay should be taken to mean "close enough to")

    400kg lifted 1m = 4000J, in 1 second = 4kW - that's a damn big motor for batteries.

    You want it reliable and safe (ie doesn't fall if you kill the power) -

    probably your best bet is to use ready made motorised actuators like:

    http://products.danahermotion.com/v41/Advisor.asp?User=Actuators_Linear&Rnd=321

     

    There are a load of people making and selling this sort of thing  - you'll need to trawl the web - I Googled "chair lift actuator" but you should also try "linear actuators" and have  a look at http://www.linak.co.uk

    who have a big range.

     

    I think you should think very hard about compromising on lifting speed (10 seconds for 1m will give you a much more reasonable 400W but remember that's output power - expect 50% efficiency on a good day so you battery must give you 800W for 10 seconds for each lift. Use a 24V battery and that's 33A so 40 cycles is 800 seconds at 33A which is only 7.3AH so your battery doesn't need to be too huge - but you need to choose one which is rated for a 15 minute discharge time.

     

    Good luck.

     

    MK

  • in reply to michaelkellett

    Ok so I am not going to worry about trying to lift the weight I can do it with a good bottle jack mounted. I just wanted to make it all electric lift butI still want the rotatio of the mass to be electric as that will still benefit from that.

    As it will be on bearings and stationary even though the weigh may be 360kg I don't need a motor that would be able to lift it as i just need to spin it. so I am thinking a 2kW motor will be adequit for that task. I won't need any special eletrical board except the one to control the motor and its speed. Thank you for all your help this may actually go from thought to prototype... will up date when something changes...

  • in reply to ljcraft12

    Penny

    It strikes me that properly supported it shouldn't need very much power to rotate.

    A merry go round at a childrens playground would be a good example.

     

    It doesn't take a lot to push it, and I'm sure most would weigh in excess of 800lbs/400Kg.

     

    Try this one

    http://www.falkirk-wheel.com/faq/36-how-much-power-is-required-to-turn-the-wheel

     

    mark

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