1000 kilo Newton meter (K/Nm) torque

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Discussion Overview

The discussion centers around the requirements for producing 1000 kNm of torque using motors and gears, with a specific output RPM of 30. Participants explore various aspects including motor specifications, gear ratios, and the potential need for a flywheel.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant seeks clarification on producing 1000 kNm of torque and the associated motor specifications, including kVA and RPM.
  • Another participant questions the clarity of the initial unit usage, suggesting a misunderstanding of the terms.
  • Some participants discuss the correct usage of kVA versus kW, emphasizing the importance of apparent power in motor ratings.
  • A suggestion is made that the original poster should calculate the power output needed for the motor to determine the required kVA and appropriate gearing to achieve the desired RPM.
  • One participant provides a specific motor configuration (150 kVA, 960 RPM) and asks for help in calculating the output torque after applying a double-stage gear reduction.
  • Another participant notes that the power required for 1000 kNm at 30 RPM must be calculated to ensure the motor can deliver the necessary torque.
  • Concerns are raised about the practical limitations of the system, including the weight of the gearbox and suggestions for alternative designs, such as hydraulic motors or different gear configurations to reduce weight.
  • A link to data on large planetary gearboxes is shared for further reference.

Areas of Agreement / Disagreement

Participants express differing views on the clarity of the initial question and the correct interpretation of motor specifications. There is no consensus on the best approach to achieve the desired torque and RPM, with multiple competing ideas and suggestions presented.

Contextual Notes

Participants highlight the need for specific calculations regarding power output and gear ratios, but the discussion does not resolve the uncertainties surrounding the optimal design or configuration for achieving the desired torque.

Who May Find This Useful

Individuals interested in mechanical engineering, motor specifications, gear design, and torque applications may find this discussion relevant.

parsci
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i want to produce 1000 K/nm of torque using motors and gear , output rpm needed is 30 and 1000 k/ nm of torque

1) motor kva? and rpm ?

2) gear ratio and size ?

3) does it also require flywheel ?
 
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You mean you want to produce 1000 kNm and a frequency of 30 RPM. The way you wrote it makes no sense.
 
I also have no idea what a motor's kva is. No doubt another botched unit usage?
 
dauto said:
I also have no idea what a motor's kva is. No doubt another botched unit usage?

No, the units are correct (although they should be written kVA). Motors (and e.g. transformers) are always rated in VA, not W. The former is the unit for apparent power whereas the latter is the unit for real power. They are related via the power factor of the load.
 
parsci said:
i want to produce 1000 K/nm of torque using motors and gear , output rpm needed is 30 and 1000 k/ nm of torque
1) motor kva? and rpm ?
2) gear ratio and size ?
3) does it also require flywheel ?

You will get better answers if you solve the problem yourself. Here's a hint to get you started: You already have enough information to calculate the power output, so you know how much power you need the motor to deliver. That will tell you what the motor kva must be; and when you're considering a motor it will be specced to deliver that power at a particular RPM. If that RPM is not 30, then you will need gears in whatever ratio will get you from the motor RPM to your desired 30RPM output.

Whether you need a flywheel or not will depend on how variable the load is.
 
Nugatory said:
You will get better answers if you solve the problem yourself. Here's a hint to get you started: You already have enough information to calculate the power output, so you know how much power you need the motor to deliver. That will tell you what the motor kva must be; and when you're considering a motor it will be specced to deliver that power at a particular RPM. If that RPM is not 30, then you will need gears in whatever ratio will get you from the motor RPM to your desired 30RPM output.

Whether you need a flywheel or not will depend on how variable the load is.

Thnks for reply , help me in getting output torque
150 kva motor 3 phase 960 rpm using double stage gear 1st stage 78 inch dia Reducing rpm 10:1 2nd stage gear 36 inch dia reducing 3:1 ,how much the output torque
 
parsci said:
Thnks for reply , help me in getting output torque
150 kva motor 3 phase 960 rpm using double stage gear 1st stage 78 inch dia Reducing rpm 10:1 2nd stage gear 36 inch dia reducing 3:1 ,how much the output torque

You want 1000 kNm of torque at 30 RPM. What power (in watts) does that represent?
If your motor delivers that power while turning whatever revs are needed to get 30 RPM after going through the gearing, it's generating the necessary torque.

(Although wise engineers will choose a motor that provides some excess capacity).
 
The practical implementation of such a system will be limited by the mass of the gear wheels and the box that holds them together. The gear box will weigh less if you use an extra stage with a final bull gear ratio closer to 3:1 than 10:1.
You might consider using an internal gear which has more tooth contact. An epicyclic with multiple planets could also help reduce total weight.

An obvious alternative to such a heavy gearbox would be to use a hydraulic motor. A hydraulic “gear motor” for example exerts the hydraulic force on many teeth. The gear ratio is determined by the relative fluid volume per revolution of the motor and the pump. It is self lubricating and the hydraulic fluid can be cooled if necessary.
 

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