The motor in the link below specifies that the load torque is 0.5kg.cm and the rotor torque is 2.3kg.cm. I don't understand the almost 5 times ratio of these torques. If I fit a 1cm radius pulley onto this motor with a weight on the end of a cord on this pulley, what weight could I reasonably expect it to lift?

https://www.ebay.co.uk/itm/3V-6V-DC...049430?hash=item284c22ee16:g:72UAAOSwiqFaToaw

 

The motor in the link below specifies that the load torque is 0.5kg.cm and the rotor torque is 2.3kg.cm. I don't understand the almost 5 times ratio of these torques. If I fit a 1cm radius pulley onto this motor with a weight on the end of a cord on this pulley, what weight could I reasonably expect it to lift?

https://www.ebay.co.uk/itm/3V-6V-DC...049430?hash=item284c22ee16:g:72UAAOSwiqFaToaw

I guess it is a question of semantics but one number is for the actual motor (load torque) and one is on the gearbox (rotor torque). Those little gearboxes come in many different ratios, this one is configured at about 5:1.

 

The gear box ratio cannot be 5:1. The specification says the motor speed is 11,500RPM and the output shaft is 40RPM.

 

The gear box ratio cannot be 5:1. The specification says the motor speed is 11,500RPM and the output shaft is 40RPM.

Then my semantics were wrong.

 

The only way the output torque should be less than the motor torque would be if the gearbox was gearing up the speed. Even if the rotor torque and output torque had been swapped over in the data sheet I do not believe a 6 volt motor consuming 300 mA rated at 11500 RPM would give 0.5 Kg cm torque. the motor to output speed ratio is about 288:1 so I would expect a better torque ratio of 5:1 (Still assuming the motor and output torque had been swapped over.) I think it is like many adverts on Ebay where the numbers quoted are meaningless.

Les.

 

The only way the output torque should be less than the motor torque would be if the gearbox was gearing up the speed. Even if the rotor torque and output torque had been swapped over in the data sheet I do not believe a 6 volt motor consuming 300 mA rated at 11500 RPM would give 0.5 Kg cm torque. the motor to output speed ratio is about 288:1 so I would expect a better torque ratio of 5:1 (Still assuming the motor and output torque had been swapped over.) I think it is like many adverts on Ebay where the numbers quoted are meaningless.

Les.

I think some copy/paste errors have occurred as the seller pushed the various versions of this motor over the years - who looks at specs? Just change the title and let the buyer beware.

 

Perhaps the higher figure relates to stall torque and the lower figure to recommended normal running torque. Given that the motor likely is from the Orient, I wouldn't put too much faith in the wording of the spec. I've come across various inconsistencies in Fleabay ads.

 

Looking at the specs for a different motor, they quoted a maximum efficiency torque and a stall torque. Could that be what the those numbers represent?

 

Looking at the specs for a different motor, they quoted a maximum efficiency torque and a stall torque. Could that be what the those numbers represent?

That sound better/reasonable.

 

Perhaps the higher figure relates to stall torque and the lower figure to recommended normal running torque. Given that the motor likely is from the Orient, I wouldn't put too much faith in the wording of the spec. I've come across various inconsistencies in Fleabay ads.

If that's right then it should be OK for my purpose. The maximum torque I am expecting is 1kg.cm.
I have ordered the motor so experiment will tell the truth.

As the motor will only be running for a short time with long rest periods I could presumably increase the motor voltage some to increase the torque.

 

Many numbers in the Ad posted spec seem a little bogus!
If the ratio is 287:1 as listed then the motor torque would be multiplied by this at the output shaft.
Max.