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# Gear Box selection, Torque Calculation

## Gear Box selection, Torque Calculation

(OP)
We have a belt dryer conveyor which is approximately 15 meter long and running at very low speed of almost 0.02 RPM. Motor is 1450 rpm and to reduce the speed of motor 2 gearboxes and pulleys are used? I want to redesign the system. how can i Calculate the torque requirement and gearbox selection. The belt weight is 1200 kg. and it's roller weight is 3500 kg. belt width is 1 meter.
Thankyou

### RE: Gear Box selection, Torque Calculation

Motor power = torque * RPM * unit corrections. You can look at the electrical power the motor requires and solve for torque. Torque losses in the gearboxes and pulleys depend on their design. The information for the gear boxes should be available from the gear box makers; belt driven pulley losses are available from any of several belt suppliers, like Gates Rubber.

### RE: Gear Box selection, Torque Calculation

(OP)
3DDave Sir, Thankyou for your kind reply, but i want to know how to calculate the torque requirement. conveyor drive is straight? how much torque is required to run belt dryer? I also want to know the power requirement of motors?

### RE: Gear Box selection, Torque Calculation

kamaqal

To calculate the torque required you first need to calculate the inertia of the 15m belt dryer conveyor and anything that is sat on the conveyor when the whole thing starts up ie from zero speed to its final speed.
The formula for that is T= I*α where I is the rotational inertia of the system and α is the angular acceleration of the rollers and mass on the conveyor.
What 3DDave was trying to tell you was that if you look on your existing motor nameplate and gearbox nameplates the information there would help you calculate this torque figure.

### RE: Gear Box selection, Torque Calculation

Your motor output will likely be the limiting factor with regards to torque in the drivetrain. Based on your OP it sounds like you have an existing motor that is capable of driving the system, so why not use that motor's characteristics to size your gear drives?

Also, a speed reduction ratio of 1450/0.02 is extremely high. Just what are the criteria for your redesigned drivetrain? Do you expect to get this speed reduction from a single gearbox?

### RE: Gear Box selection, Torque Calculation

My favorite extreme reduction scheme: https://www.youtube.com/watch?v=5q-BH-tvxEg Machine with Concrete - Arthur Ganson

It's not clear what part is running at .02 RPM. Is it a drive roller or the entire belt?

Also it isn't clear what the goal is. Without a goal it sounds more like a new design with incomplete constraints than a change to an existing one. If one is moving material, power, not torque, is the primary consideration. This includes the energy required to accelerate material that drops on the belt and friction in the bearings and losses in flexing of the belt.

### RE: Gear Box selection, Torque Calculation

3DDave-

That video is awesome! Nothing but backlash and strain.

### RE: Gear Box selection, Torque Calculation

(OP)

"Tbuelna" your idea is great to use the existing motor rating for further calculation.
3DDave sir i was interested to learn the art of selection of gearbox that's why i dropped question over here.

### RE: Gear Box selection, Torque Calculation

to kamaqal,

Torque requirement can be calculated from power requirement, see formula below:
T = P/(6,28 * n) with P = Fe * v and Fe = µR * g * (M + Mb + Mr)
Note:
T = Torque Requirement (Nm)
P = Power Requirement (Watt)
Fe = Effective Force (N)
v = Velocity (m/s)
µR = Coefficient of friction
g = gravity (m/s)
M = Material weight (kg)
Mb = Belt weight (kg)
Mr = Drum pulley weight (kg

for read more, visit my blog: http://www.mymachineinfo.com/2015/04/calculation-o...
thanks

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