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P.Nithin Kumar
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Gear Box Torque

12/22/2010 10:17 AM

Is there any Direct formulae for calculating gear box torque.

Kindly suggest

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#1

Re: Gear box torque

12/22/2010 10:26 AM

What are you torquing about?

Max. rated output torque? Output torque vs. input torque? Static torque?

Please be more specific.

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Baxter
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#2
In reply to #1

Re: Gear box torque

12/22/2010 10:30 AM

hah. What are you torquing about. I like your style
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P.Nithin Kumar
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#3
In reply to #1

Re: Gear box torque

12/22/2010 10:56 AM

All , Input torque & output torque.And i dont know what is static torque ,pl let me know

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JohnDG
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#4
In reply to #3

Re: Gear box torque

12/22/2010 11:08 AM

Roughly, output torque = input torque ÷ gear ratio (less losses due to friction etc). If the output rotates faster than the input, the output torque will be less than the input torque.

The other stuff is all specific to the gearbox design & construction. Best to go by manufacturer's data.

[I didn't mean to mark this OT, because it isn't. I didn't notice you'd marked yours before I clicked 'Submit'. Don't know why you marked your's OT - because it is very much on topic.]

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P.Nithin Kumar
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#6
In reply to #4

Re: Gear box torque

12/22/2010 12:10 PM

Here , i want how to calculate input torque and output torque and what are the parameters involving in this.

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JohnDG
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#8
In reply to #6

Re: Gear box torque

12/22/2010 5:40 PM

Do you want to calculate input torque from output, or output from input? They both depend on the gearbox ratio and losses - and each other!

I've told you the basic relationship.

If you need more, give more information. Otherwise you're on your own.

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#9
In reply to #6

Re: Gear box torque

12/22/2010 9:12 PM

Geez! What is your input torque coming from? A motor? If so, you can't CALCULATE input torque. You have to get it from the MOTOR SPECIFICATIONS. Once you have the INPUT TORQUE, you can ESTIMATE the output torque by applying JohnDG's spot-on formula (Post #4).

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P.Nithin Kumar
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#11
In reply to #9

Re: Gear box torque

12/23/2010 2:27 AM

Hi ,

With motor specification how can i calculate input torque .

e.g., if motor rpm is 1500 , 2 H.P (1.5 KW) , 415 V

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#19
In reply to #11

Re: Gear box torque

01/04/2011 11:31 AM

What is the load torque and the gearbox ratio?

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Mukesh0861
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#5

Re: Gear box torque

12/22/2010 11:39 AM

Simply ref. the engg. theory book. You know power to be trasmitted at specific rpm, torque can be known.
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P.Nithin Kumar
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#7
In reply to #5

Re: Gear box torque

12/22/2010 12:12 PM

Which author should i refer to get my doubt clear

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#10
In reply to #7

Re: Gear box torque

12/22/2010 9:21 PM

What do you think torque is? I need to know what you know about this so I don't waste time explaining what you already know OR direct you to some basic WIKI page if you don't have even the basic knowledge to formulate a coherent question.

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P.Nithin Kumar
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#12
In reply to #10

Re: Gear box torque

12/23/2010 2:45 AM

Hi,

Torque is nothing but a load acting on the gear. I think in this Motor rpm ,HP involves .,but how to calculate i dont now .pl suggest

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#20
In reply to #12

Re: Gear box torque

01/04/2011 11:32 AM

Torque multiplied by angular velocity equals shaft power.

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#13

Re: Gear Box Torque

12/23/2010 10:47 AM

Torque (Nm) = (Power (kW) x 9550)/rpm

In your example above (1.5 kW motor, 1500 rpm) I'm presuming that the 1.5kW refers to the electrical rating; allow say 85% efficiency, so 1.275 kW power out & therefore 8.12 Nm @ 1500 rpm.

In terms of the torque out of the gearbox, use the same formula, e.g. gearbox output is 30 rpm, motor is 1.5 kW assume 85% motor efficiency & 95% gearbox efficiency (81% overall), torque out is ((1.5 x 0.81) x 9550)/30 = 387 Nm as a rough guide.

What specifically are you trying to work out?

There are a number of online calculators, for instance here

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P.Nithin Kumar
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#14
In reply to #13

Re: Gear Box Torque

12/23/2010 12:25 PM

Thank you so much for information,I am very much close to my Answer.

I had few doubts, what does 9550 means and for calculating gearbox output torque ,gear number of teeth and gear radius involves or not? and again for calculating roller/conveyor shaft torque (also involves roller dia)which is couple to the gear box how can we calculate

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#21
In reply to #14

Re: Gear Box Torque

01/04/2011 11:33 AM

What is the ratio between revolutions per minute and radians per second?

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#15

Re: Gear Box Torque

12/23/2010 1:03 PM

The relationship is explained fully here. The figure 9550 expresses the relationship between torque, power & rpm and has nothing to do with any gearing; look about three quarters of the way down the linked article under "Conversion to other units". I've simplified this equation by approximating to 9550, it should really be 9549.296586 but in practical situations this is more than accurate enough.

If you just consider the output rpm of the gearbox you don't need to work through the gear ratio, just calculate as per my original example.

Torque is expressed in this case in Nm or Newton metres; 1 Nm is a force of 1 Newton at a metre distance, so if the output (as above) of the gearbox is 387 Nm and it is directly driving a conveyor roller of say 100mm diameter the pull of the conveyor can be found by dividing a metre by the drive roller radius (50mm or 0.05m) and multiplying by the torque; so 1/0.05 = 20 and 387 x 20 = 7740 Newtons.

It can make more sense to convert that into kilograms of pull when considering conveyors. In this situation 1 kg = 9.81 Newtons, so 7740 Newtons = 789 kg of pull

In summary then a gear motor rated at 1.5 kW and 30 rpm directly driving a conveyor with a 100 mm diameter drive roller should produce around 789 kg of pull on the conveyor belt.
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P.Nithin Kumar
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#16
In reply to #15

Re: Gear Box Torque

12/24/2010 12:35 PM

Thank you so much i got my answer !!!!!!!

Only 1 Thing i want to clarify is how 9550 constant links to torque,power& rpm.

Pl Clarify.......

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#17
In reply to #16

Re: Gear Box Torque

12/24/2010 2:24 PM

Power = Torque x Angular velocity

Convert the angular velocity into RPM and then convert (the Power is in KW so a factor of 1000 will be there) and that brings the constant 9550 (or 9549.2965855137201...)

It is elementary my dear watson (taught in schools)

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P.Nithin Kumar
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#18
In reply to #15

Re: Gear Box Torque

12/25/2010 10:43 PM

Why we have to do 1/0.05 , I didn't understood . pl Explain

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#22
In reply to #18

Re: Gear Box Torque

01/04/2011 11:35 AM

Re-read the posting. The explanation is in there. It just needs looking for.

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#23

Re: Gear Box Torque

02/12/2011 12:05 PM

DearMr. Nithin Kumar,

H.P = 2 X PI X N X T/ 4500

where H.P = HORSE POWER. PI = 22/7, N = R.P.M, T = TORQUE in Kg.M

You put the In-Put Speed in this equation, you will get the In-Put Torque, put the Out-Put Speed, you will get the Out-Put Torque.

DHAYANANDHAN.S, INDIA
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#24
In reply to #23

Re: Gear Box Torque

02/12/2011 5:05 PM

You may need to think about the units you're using there. You have RPM, HP and kgm - mutually incompatible without conversion factors.

HP = RPM x T x K, where K is a constant, but it isn't 22/7 using your units.

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#25
In reply to #24

Re: Gear Box Torque

02/17/2011 11:58 AM

Dear Mr. John DG,

Thanks for your comment.

The formula is 2 x Phi (this is 22/7) x N (RPM) x T (torque in Kg.M)/4500

I am finding difficult to insert Phi symbol hence used 22/7 as Phi=22/7.

You can cheque up this by using this formula for a known value of speed, TORQUE or H.P with one un-known in the above equation.

CR4 members can guide (me) how to insert the symbol.

Thanks,

DHAYANANDHAN.S.
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