Static Motor Speed Under Dynamic Load

In summary, the speaker is looking for a motor that can pull and retract a wire at a constant speed under a dynamic load of 20-500 lbs. They are wondering if a motor is the right choice or if they should consider hydraulics. The suggested solution is a brushless DC motor with an electronic speed control, which is lighter and can be geared down to achieve the desired speed. The weight and ability to withstand the load will depend on the specific motor and controller chosen. The speaker also mentions the use of flywheels or hydraulic accumulators to smooth out fluctuations in torque. Another suggestion is an outrunner DC brushless motor, which can provide one horsepower and is suitable for lifting objects like in the Batman franchise.
  • #1
omalleyt
15
0
Hi. For a project of mine, I need a motor that can dole out and pull in a wire at a constant speed under a dynamic load. The load will be anywhere between 20-500 lbs. The speed will be about 1 ft/sec. Any idea about how I can achieve this effect? Is a motor even the right way to go or should I be looking at hydraulics? Thanks for any help!
 
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  • #2
I have a suspicion weight will be an issue.

AC induction motors turn at fairly constant speed. But a brushless DC motor can be made to rotate at a constant speed using an electronic speed control and is far lighter.
 
  • #3
How much (approximately) would the DC motor weigh, and would it be able to withstand the 500lb load?
 
  • #4
At one foot per second, the motor will need to be geared down. The question is not how much weight, but how many horsepower. This happens to be one horsepower, or a little more, for your one foot per second requirement.
 
  • #5
Many industrial motors can operate on this kind of condition. For example, think of a motor on a lathe. The loads are drastically changing but the speed remains constant. The combination of motor and controller will dictate how the motor runs.
 
  • #6
Some motors driving fluctuating dynamic loads use large flywheels as temporary energy storage to smoothe out the torque requirements; e.g., air compressors. For larger energy storage, hydraulic systems use compressed air reservoirs.
Bob S

[edit] The reservoirs are actually called accumulators. They have a bladder in them to prevent direct contact between air and fluid.
 
Last edited:
  • #7
You can get one horse power out of an outrunner DC brushless motor 2" diameter and 2" long. It isn't cheap, and will need to be geared down like any other motor selection. If affordable, it would be the way to go to cable lift for the batman thing.
 

1. What is static motor speed under dynamic load?

Static motor speed under dynamic load refers to the speed at which a motor runs when it is subjected to a varying or fluctuating load. This means that the motor is running while also experiencing changes in its load, which can affect its speed.

2. How is static motor speed under dynamic load measured?

The static motor speed under dynamic load is typically measured in revolutions per minute (RPM) using a tachometer. The tachometer is a device that measures the rotational speed of a motor or other rotating object.

3. What factors can affect static motor speed under dynamic load?

There are several factors that can affect the static motor speed under dynamic load, including the type of motor, the type of load, the motor's design and construction, and the operating conditions. Other factors may include the age and condition of the motor, as well as any external forces acting on the motor.

4. Why is it important to measure and understand static motor speed under dynamic load?

Measuring and understanding the static motor speed under dynamic load is important because it can help engineers and scientists optimize the performance of motors and other rotating equipment. By understanding how a motor responds to changes in its load, they can make adjustments or modifications to improve its efficiency and reliability.

5. How can the static motor speed under dynamic load be improved?

The static motor speed under dynamic load can be improved by using a motor with a higher horsepower rating, optimizing the motor's design and construction, and adjusting the operating conditions to better suit the motor's capabilities. Other methods may include using variable speed drives or implementing load balancing techniques to distribute the load evenly across multiple motors.

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