Trying to calculate motor kW/reduction drive for lift of 100kg at 0.8m /sec

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Discussion Overview

The discussion focuses on calculating the appropriate motor size and reduction gearbox for lifting a weight of 100 kg at a speed of 0.8 m/s using a cable drum. The conversation includes considerations of motor specifications, gear reduction, and drum diameter, with an emphasis on practical application in a lifting mechanism.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks assistance in determining the motor size and reduction gearbox needed for lifting a 100 kg weight at a specified speed.
  • Another participant asks for clarification on the application and the height to which the weight needs to be lifted.
  • A suggestion is made to calculate the required power and then double it for safety or efficiency considerations.
  • One participant calculates the change in potential energy per second, estimating it to be approximately 784 watts or 1 HP, while ignoring acceleration.
  • A formula is provided linking gear reduction, drum diameter, and motor RPM to the cable speed, with an example calculation given for a specific motor RPM and gear reduction.
  • Another participant expresses a desire for the original poster to perform the calculations themselves.

Areas of Agreement / Disagreement

Participants present various approaches and calculations, but there is no consensus on the specific motor size, gear reduction, or drum diameter. The discussion remains unresolved with multiple viewpoints and methods proposed.

Contextual Notes

Assumptions regarding acceleration are not addressed, and the dependency on specific definitions of motor RPM and gear reduction ratios is implied but not clarified. The scope of the calculations may vary based on the actual application and parameters that have yet to be determined.

surfguy
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TL;DR
need to calculate motor kw/reduction drive for lift of 100kg at .8mtrs /sec
Hi
need to calculate 240v/315v motor size attached to reduction gearbox (reduction unknown) to lift a weight of 100kg on cable drum .8mtr/sec.
Drum dia not determined yet.
motor size not determined yet.
any help is greatly appreciated as this seems to be out of depth of many motor drum winch suppliers and myself.
thanks
 
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Welcome to PF.

What is the application? How far do you have to lift it?
 
Single or 3 phase?

Step 1: calculate the power you need, then double it.

Step 2: pick a common motor rpm and "reasonable" drum size, then calculate the reduction. Adjust as seems appropriate.
 
Ignoring acceleration.
The change in PE per second = m·g·h = 100 * 9.8 * 0.8 = 784 watt ≈ 1 HP.
 
Finally, the gear reduction ##GR##, drum diameter ##d## (in meters), and motor ##RPM## are linked in the following way:
$$v = \frac{\pi}{60} \times d \times \frac{RPM}{GR}$$
Or
$$d = \frac{19.1 \times GR \times v}{RPM}$$
Where ##v## is the cable speed in meters per second. For example, given a motor of 1750 RPM and a gear reduction of 10:1, the drum diameter would be 0.087 meters or 8.7 cm to get a cable velocity of 0.8 m/s.
 
I was hoping OP would calculate them...
 
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