Checking My Gearbox RPM Calculations for Conveyors

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Discussion Overview

The discussion revolves around the calculations of gearbox RPM for conveyor applications, specifically focusing on two conveyor scenarios involving 2-inch diameter rollers. Participants evaluate the calculations and assumptions regarding speed, gearbox ratios, and motor RPMs.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant calculates the speed of a conveyor traveling 30 feet in 4.5 minutes as 6.667 feet per minute, suggesting a gearbox ratio of about 12:1 based on this speed.
  • Another participant challenges the 12:1 gearbox ratio, stating it depends on the motor RPM and calculates a required reduction of 117.8:1 for a 1500 RPM motor based on the roller's RPM of 12.733.
  • For the second conveyor traveling 28 feet in 20 seconds, one participant calculates a speed of 1.4 ft/sec, leading to an RPM of 160, while another recalculates this to 160.5 RPM and suggests a gearbox ratio of 9.35:1 for a 1500 RPM motor.
  • A participant questions how power is transferred to the rollers, inquiring about the connection to a main drive shaft and the presence of any chain or belted reduction between the line shaft and gearbox.
  • One participant mentions using a motor speed of 1750 RPM instead of 1500 RPM in their calculations.

Areas of Agreement / Disagreement

Participants express differing views on the gearbox ratios and the calculations involved, indicating that multiple competing views remain without a consensus on the correct approach or assumptions.

Contextual Notes

There are unresolved aspects regarding the assumptions made about motor speeds and the method of power transfer to the rollers, which may affect the calculations presented.

SevenToFive
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I am not really buying my calculations of a gearboxes rpm for some conveyor applications. First conveyor has to travel 30 feet in 4.5 minutes with 2" rollers. If I divide 30' by 4.5minutes I get 6.667feet/minute and with a 2" diameter the gearbox should be about a 12:1 ratio.
The other is a conveyor to travel 28 feet in 20 seconds with 2" diameter rollers. IF I did this correctly I divided 28ft by 20 seconds to get 1.4ft/sec, which would give me 160rpm.

Thanks for checking my work.
 
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30 ft in 4.5 min = 6.667 ft per min = 80” per min.
A 2” diam roller has 6.283” circumference. So roller will be at 12.733 RPM.
How you get a 12:1 gearbox ratio I do not know. It depends on the motor RPM.
A 1500 RPM motor will need a reduction of 1500 / 12.733 = 117.8 : 1 ratio.

28 feet in 20 sec = 84 ft per min = 1008” per min.
2" diameter roller has 6.283” circumference. So roller will be at 160.5 RPM.
A 1500 RPM motor will need a reduction of 1500 / 160.5 = 9.35 : 1 ratio.
 
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SevenToFive said:
I am not really buying my calculations of a gearboxes rpm for some conveyor applications. First conveyor has to travel 30 feet in 4.5 minutes with 2" rollers. If I divide 30' by 4.5minutes I get 6.667feet/minute and with a 2" diameter the gearbox should be about a 12:1 ratio.
The other is a conveyor to travel 28 feet in 20 seconds with 2" diameter rollers. IF I did this correctly I divided 28ft by 20 seconds to get 1.4ft/sec, which would give me 160rpm.

Thanks for checking my work.
How is power transferred to the 2" rollers?

For instance, are they connected to a main drive shaft equipped with pulleys via heavy "rubber bands"?
Conveyor Lineshaft drive.jpg


If so, is there a chain or belted reduction between line shaft and gearbox?
 
Baluncore said:
30 ft in 4.5 min = 6.667 ft per min = 80” per min.
A 2” diam roller has 6.283” circumference. So roller will be at 12.733 RPM.
How you get a 12:1 gearbox ratio I do not know. It depends on the motor RPM.
A 1500 RPM motor will need a reduction of 1500 / 12.733 = 117.8 : 1 ratio.

28 feet in 20 sec = 84 ft per min = 1008” per min.
2" diameter roller has 6.283” circumference. So roller will be at 160.5 RPM.
A 1500 RPM motor will need a reduction of 1500 / 160.5 = 9.35 : 1 ratio.
I was using 1750 rpm for a motor speed. Thanks again for the help.
 

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