[Nataraja06]

Please specify how to calculate the torque required for 10Ton Load

[jcaron2]

The required torque is equal to the force (10 tons) times the radius of rotation. For example, let's say you're lifting the 10 ton load with a cable. The cable wraps around a large spool (let's say it's 2 feet in diameter) which is driven by a motor and a gearbox. The torque required at the spool would be the force (10 tons) times the radius of the spool (1 foot), for a net result of 10 foot-tons. If you had a motor which could generate, say, 0.1 foot-tons of torque, that would mean you'd need a gearbox with a 100:1 ratio to increase the torque.

If your situation is different (for example, you're lifting the load with a boom or a lever), please provide more details and one of us will be able to help you better. Or if you're not sure how to calculate the torque in more common units such as Newton-meters or foot-pounds, just ask.

[Nataraja06]

Hi Jcaron2

Thanks for the reply,but my question is that not to lift the 10ton load,it should be rotated.

My job is like a large hollow shell weighs 10Ton.That shell diameter for example 4.5m,we are rotating the

Shell by means of conventional rotator having two wheels of diameter 300mm two sides each and 100mm

Width ,and having a twin-drive(for ex. LH & RH).So the load is acting radially,

Required speed of the wheels should be 1500rev/min.For this how to find torque,how to select gearbox and

Motor.Please sir help me out I am struggling in basics also.

If any other details u need please ask sir...

Thanks & Regards,
N.Natarajan

[jcaron2]

In that case, if you're trying to rotate the load, rather than lift it, the required torque will depend on how fast you need to accelerate the rotation. Maintaining 1500 rpm is easy once the shell is already spinning (unless there's a LOT of friction); getting it up to that speed is the hard part.

Since you have a known requirement for the final rotation speed, you don't have a lot of choice for the gearbox gear ratio. It will have to be chosen such that the motor's speed ultimately translates to 1500 rpm after the gearbox and twin-drive. For example, if your motor's running speed is 3000 rpm, you'd need to have a 3000:1500 (i.e. 2:1) total gear ratio through the gearbox and the twin-drive. Thus, your main choice really comes down to the motor. Do you already have a motor to drive this, or are you trying to specify that as well?

Once you have a motor in mind, the torque curve (torque versus angular velocity of the motor) will tell you how much torque the motor is providing at a given speed. You can then multiply the torque and divide the speed by the combined gear ratio of the gearbox and drive. That gives you the effective torque curve right at the axis of rotation of the load. You can then calculate the angular acceleration with the formula

,

where is the torque, I is the moment of inertia (which you can probably look up depending on the shape of your "shell"), and is the angular acceleration. Note that this formula is analogous to Newton's second law F=ma.

Once you know the angular acceleration, you can compute the angular speed as

,

where is the change in angular speed (i.e. rotational speed in radians per second; it equals times the speed in revolutions per second), and t is the time, in seconds.

If the torque of the motor is roughly constant, then the above calculation is quite easy. You can simply plug in the numbers for acceleration and velocity, and solve for time to find out how long it would take for the rotation to come up to speed. If it's not fast enough, you'll need to choose a motor with higher torque.

If the torque curve is not constant, the proper way to do the calculation is with calculus. However, you can get a pretty good approximation by choosing a small increment of time, t (for example, 1 second), then calculating the change in velocity assuming the torque is constant for that small interval. Then, once you have the new velocity, look up the new value of torque on the torque curve, and solve the equation again to find the change in velocity after the next time interval. Repeat until the motor is up to its final speed.

[Nataraja06]

Thanks for the reply, I have worked out as per procedures.

Sir one more question,its about mechanism to avoid drift in the rotating shell using any anti-drift

Mechanism you may know please let me. It should be either using hydraulics or pneumatics not manual one,why

Bsce we are doing manual one.

Waiting for your reply,

Thanks,


N.Natarajan

[jcaron2]

Sorry, that's way out of my area of expertise. I just don't know.

You may want to try posting a separate question on this site just about the anti-drift portion. Since this thread is quite old now, not many people will read it. A new question will probably be seen by a lot more people who could potentially answer it for you.

Good luck!

[Nataraja06]

OK thanks.

[jalavadiyaravi]

How to select gearbox for lift 200kg load at 2 meter hight with the output rpm of gearbox 10, rop mounted on rop drum direct .