Need help figuring required horsepower of electric motor

In summary, the conversation discusses the building of a conveyor system for moving materials up to a second floor. The system needs to be able to move at least 500 lbs at a rate of 105 feet per minute. The motor chosen is a reversible one with a speed of 1750 RPM and a 40:1 reducer. Based on calculations, a 1 HP motor is determined to be the minimum requirement for the system. There is also a discussion about using a 40:1 speed reducer and its effect on torque and power.
  • #1
HandymanExpres
2
0
I have built a conveyor system but still need to power it. It is not a conveyor belt, but rather a trolley of sorts for moving materials up to the second floor. It runs parallel to stairs for about 17 or 18 feet in my garage at an angle of apx 38°. It needs to be able to move at least 500 lbs. but I would rather calculate it to accommodate more like 1000. It needs to move at a rate of about 105' per minute. It rolls on hard rubber wheels but I may switch to steel wheels. The motor will have a pulley on it which winds a high tensile strength material just like used for seatbelt material. I will be using a reversible motor with a speed of 1750 RPM and a reducer. I saw a 40:1 reducer available, so I made calculations based on it for my pulley. I came up with a pulley size of 9.14" in diameter and a circumference of 28.7". I know that with every wind the pulley will get larger, thereby increasing the speed, but it will be negligible for what I am doing. I know that there is friction loss here and there, and the exact speed of the motor may not be 1750, so once this is operational I may remake the pulley size up or down to my liking. I just need to know the HP requirements needed. My motto is "Overkill is underrated" so I would oversize the motor in a heartbeat, but I do not want to undersize it.
 
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  • #2
Welcome.
I assume 105' is 105 feet.
The time needed will be (18 feet / 105' ) = 0.171 minutes = 10.28 seconds
Up 18 feet * Sin(38°) = 11 feet vertical = 3.3528 metres.
m = 500 pounds = 226.8 kg
Potential Energy change = m*g*h = 226.8 * 9.8 * 3.3528 = 7452. joule
That is 7452. joule / 10.28 seconds = 724.9 joule/sec = 724.9 W = 0.972 HP

The absolute minimum motor would be 1 HP.
 
  • #3
In English Units: ( to avoid metric conversions if you wish )

1 HP = 550 foot-pounds/second

500 pounds x 11 feet / 10.28 seconds = 535 ft-lbs/sec

535 ft-lbs/sec / ( 550 ft-lbs/sec )/HP = 0.972 HP
 
  • #4
OK. Next question. If I use a 1 HP motor, and put a 40/1 speed reducer on it, does that just change the torque or the HP also?
 
  • #5
Power = torque * RPM
The gearbox is a transformer, it transforms the ratio of torque to RPM.
The power does not change, apart from a couple of percent loss in the gearbox.
 

1. How do I determine the required horsepower of an electric motor?

The required horsepower of an electric motor can be determined by calculating the torque and speed requirements of the machine or equipment being powered. The formula for horsepower is HP = (torque x speed) / 5252. Once you have the torque and speed values, you can plug them into this formula to calculate the required horsepower.

2. What factors should I consider when figuring out the required horsepower of an electric motor?

Some important factors to consider when determining the required horsepower of an electric motor include the load or weight being moved, the speed at which the motor needs to operate, and any additional factors like friction or resistance. It is also important to consider the efficiency of the motor, as this can affect the required horsepower.

3. Can I use a smaller or larger motor than the calculated required horsepower?

It is generally not recommended to use a smaller motor than the calculated required horsepower, as it may not be able to handle the workload and could potentially overheat or fail. However, using a slightly larger motor than the calculated required horsepower is usually acceptable, as long as it does not exceed the maximum load and speed capacity of the machine or equipment.

4. How do different types of electric motors affect the required horsepower?

The type of electric motor being used can have an impact on the required horsepower. For example, a DC motor typically requires more horsepower than an AC motor to achieve the same output. Additionally, different types of AC motors, such as induction or synchronous, may have different efficiency levels, which can also affect the required horsepower.

5. Are there any online calculators or tools available to help me figure out the required horsepower of an electric motor?

Yes, there are many online calculators and tools available to help you determine the required horsepower of an electric motor. These tools typically require you to input information such as the load, speed, and type of motor, and will then calculate the required horsepower for you. However, it is important to double-check the results and consider any additional factors that may affect the required horsepower.

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