Calculating Single Gear Ratio

[bhuman]

Hi.

I am designing a model for a vehicle. The power source is solar energy, providing power to a single 12 volt motor of about 1W. Through tests I have calculated the stall torque and max RPM of this motor, and therefore a rated torque of 0.00154 Nm. At this load the motor should ideally spin at 6000 RPM (according to tests). It is therefore necessary to use a gear system to increase the torque at the wheels and reduce the RPM so that the model is able to start moving without a clutch, and maintain a desirable speed when moving. The model weighs 8Kg and has 4 wheels of radius 4.5cm. There is no target speed, we are just aiming for maximum efficiency.

My question is, how do you calculated a gear ratio for a single gear, so that the model will move efficiently and that the motor is loaded to its rated torque.

Any help would be much appreciated!
Thanks in advance,

Ben

 

[Navin A S]

To calculate the gear ratio for a single gear, you will need to consider several factors. First, you need to determine the torque output of the motor, which is equal to the rated torque multiplied by the gear ratio. So, if your motor's rated torque is 0.00154 Nm, then the torque output at the wheels will be 0.00154 Nm x Gear Ratio. Next, you need to determine the speed output of the motor, which is equal to the max RPM divided by the gear ratio. So, if your motor's max RPM is 6000, then the speed output at the wheels will be 6000 / Gear Ratio. Finally, you need to consider the load on the motor. This will depend on the weight of the model and the radius of the wheels. The load can be calculated by multiplying the weight of the model by the radius of the wheels. So, if your model weighs 8 kg and the wheels have a radius of 4.5 cm, then the load on the motor is 8 x 4.5 = 36 kg. Once you have all of this information, you can calculate the gear ratio by dividing the torque output by the load. So, if the torque output is 0.00154 Nm and the load is 36 kg, then the gear ratio would be 0.00154 / 36 = 0.000043. This means that with a gear ratio of 0.000043, the motor will be loaded to its rated torque and the speed output at the wheels will be 6000 / 0.000043 = 138,889 RPM.