# Thread: How to Calculate Load Torque & Motor Power

1. Join Date
Jan 06
Posts
4

## How to Calculate Load Torque & Motor Power

Any one can help me to calculate Load Torque and Power Motor for gear box in Conveyort belt application? Thanks..

Regards

Amrizal

2. R.Gopal - Chennai, India Guest

## Torque and Power

You mean Full load Torque ?

Use this formula-

T = HP x 5252/rpm

T = torque (in lb-ft)
HP = horsepower
5252 = constant
rpm = revolutions per minute

3. Dear Amrizal

In normal modern units :

Power = Torque x radian speed

2 x pi x rpm
kW = kNm x ------------------
60

rpm of belt-driving drum

or

rpm of drive

gearbox ratio = rpm driving drum / rpm drive

etc.

But, may be you are referring to the belt conveyor design, which is much more complicated.

Then it is better to orentate yourself with literature, experts and manufacturers.

success

4. Join Date
Jan 06
Posts
4

## This is the case

Dear All

Thanks for your help, I really appreciate it. I will explain the case. It's happened with one of my relation. They have upgraded the conveyor in terms of capacity. Hence it is getting overloaded and unable to move when fully loaded.

-Motor : 110 kW
-Gearbox: Citroen 95 kW (P/N 66997, year:1987)
-input/output speed: 1480/64.92 rpm
-Shaft position: Right angle
-Output shaft: solid
-Application: belt conveyor (thick: 10mm, width: 1400mm, long: 370 m)
-Accesories: Backstop
-Motor-gearbox: using fluid coupling

After upgrade: -> New belt convey (thick: 15mm, width: 1400mm, long: 370 m)
or
- Motor : 150 kW
-Gearbox: Citroen 95 kW (P/N 66997, year:1987)
-input/output speed: 1480/64.92 rpm
-Shaft position: Right angle
-Output shaft: solid
-Accesories: Backstop
-Motor-gearbox: using fluid coupling

The problem after upgrade is that new belt conveyor which is more thick caused more load to the drive system. Hence, if conveyor in full load condition and stopped, the drive system can move the conveyor. They want me to give a proove that changing the Power of Motor won't solve this problem. So, I should know how to calculate the Motor Power and Torque?

But for the belt density, I really don't know because they just give me an additional data:

- Lime stone density: 2 ton/m3
- Belt density: 1.2 ton/m3
- Max lime stone above conveyor: 111 m3
- Pulley radius: 0.4055 m

If there is any additional data needed, don't hesitate to contact me soon. Thank you very much.

5. Dear Mr. Amrizal

When you are changing the capacity, you have to redesign the conveyor and provide the various items / components accordingly. Obviously, in such case, one tries to make a design in such a manner that there are minimum changes in existing items so that the item to be replaced are minimum. You have to follow the following steps while revising the capacity of conveyor :
1) I presume you are not changing the belt width. Possibly you are only increasing the speed to get the required capacity. However, if the speed becomes excessive to achieve the capacity for a particular belt width then you have to increase the belt width and use appropriate speed.
2) If the belt width is same, you need to examine / check the suitability of the existing idlers.
3) Now design the conveyor according to the revised parameters. There are well-established design procedures for designing the conveyor. This is a bg subject and cannot be narrated in this forum in few sentences or pages.
4) The conveyor design one has to first decide the tractive pull or sum of all resistances. The sum of resistances = tractive pull. The tractive pull multiplied by the drive pulley radius will give you the load torque. There is no short cut for deciding the load torque. This cannot be calculated from motor side.
5) Having decided the load torque, you can decide the required power at motor shaft, available motor size, gear ratio and so on.
6) I will suggest you to take the help of conveyor designers, who may be also available in your country. You will be expending in pennies for design charges, but ultimately you will be saving pounds in your procurement and project implementation.

Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
Author of Book : Belt Feeder Design and Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Email : parimul@pn2.vsnl.net.in
Tel.: 0091 (0)20 25882916

6. vinay gupta Guest
Dear Sir,
can you help me how the value of contant 5252 has came in the formula of torque:
T=HP*5252/RPM

Thanks Vinay Gupta

7. Registered User
Join Date
Mar 03
Posts
1,641
5252 = 33,000 / ( 2 * PI )

Hope this helps.

8. vinay gupta Guest
I just want how the 5252 is generate.
and what is 33000 and PI in your reply

9. Registered User
Join Date
Mar 03
Posts
1,641
From my basic engineering training 30+ years ago ---

HP = 2 * PI * N (Rev/min) * T (ft lbf) / 33,000

(I don't think it's changed)

10. The definition of horsepower is:

HP = 33,000 lbs lifted one foot in one minute.

Some englishman invented it when he invented the measure of the foot, the bushel, the peck and so on. Probably when the steam engine began to replace the horse in rememberance.

PI is the circumferance of the circle when the diameter is unity or = 1, as circumference = diameter x PI.

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