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Engineering
Mechanical Engineering
Calculations - some fundamentals
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[QUOTE="Merlin3189, post: 5484934, member: 542077"] I think you are overestimating the average power here. Although 5 boxes on one side is the max load, it does not apply for the whole 6m lift. Once the boxes have moved up about 1.2m, the top one is at the top, then starts to fall. For the next 1.2m or so, you are lifting 3 boxes (4 up and 1 down), then for 1.2m lifting one box (3 up 2 down) and after that you get a free ride for the next 5.4m. (that's very rough because there is a not a sudden change, but a gradual one as boxes move across at the top and bottom. I didn't try to be more precise without the centre to centre distance and diameter of the wheels.) You still need your peak torque and peak power, but the average power is much lower. I'd say the average load is under 300 kg, so your average power under 600 W. (Actually I think load is nearer 200 than 300kg, so that could be your friction allowance!) Simon is quite right about the algebra of course, but it worried me also: I would not expect that to happen. The reason is that you have a top pulley for the drive exactly the same size as the circle round which the boxes are moving. Because of this, the speed of the drive belt is exactly the same as the belt carrying the boxes and your calculation simply gives the speed of the drive belt - obviously dependent only on the drive pulley and motor rpm. This gives a very low rotational speed for pulley 1, hence your gearbox on the motor. You may find you can specify the motor & gearbox as a unit - output speed and torque, average and peak power. Looking at the RH diagram pulley 2 looks smaller than in the LH diagram. Either way (unless there is some further gearing at the top pulley) the tension in the drive belt is at least the tension in the box carrier, say peak 1000kg (x g Newtons.) I'm no expert on drive belts: it just sounded a lot to me. Maybe you need to consider a chain? Apart from the strength, any slippage of a rubber belt at that tension could generate a lot of heat. [/QUOTE]
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Calculations - some fundamentals
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