Phidgets Forums

Speaking of DC Motor when a gearbox is involved sometime I can read ex. 1.4:30 or 30:1 or 1:30. I just show some fictive numbers and combo... What that mean and do I need to take any of that into account?'¨'

those numbers are the gearbox "ratio" - for example a 30:1 means every 30 rotations of the input shaft on the gearbox, would produce 1 rotation on the output shaft of the gearbox. This is typically proportional to the increase in torque you will get from the gearbox. so a larger number (i.e., 60:1) would have more torque than the 30:1, but rotate at half the speed.

Hi

Ok, thank´s

That mean that the motor --> https://www.phidgets.com/?tier=3&catid= ... rodid=1077 har ratio 4.9:1. I assume that 4.9:1 can read "4.9":1 or 4/9:1 in that case the motor has 5.6kg-cm of torque in s speed of 810 RPM.

I also assume that torque are 5.6 in 810 rpm and 5,6*2=11.2 kg-cm in 810/2= 405 rpm, correct?

The gearbox ratio listed in the product name (i.e., "42DMW61 NEMA17 Brushless Motor with 4.9:1 Gearbox") is usually an approximation of the ratio, and the actual specific gearbox ratio is always listed in the Specifications tab of the product. For this motor, it is listed as 4 7⁄8 : 1, which is actually (4 + 7⁄8):1, or "4.875":"1"

The torque for the motor is specified in not in terms of speed of the motor, but is based on the supplied voltage and current to the motor, and is likely a maximum torque specification based on that motor's 24V/3.5A specification. Brushless motors have their own unique torque vs speed relationship, you can search for graphs relating the two on google for a general idea.
The rated speed of 810RPM is the maximum speed you will get from the motor with a 24V supply.

I hope that answers your question...

Hi

Yes it makes sense that the rpm, torque is depenedent of the power and the voltage. Can you calulate the torque and the RPM if you just have the ratio?

The calcualtion maybe require more ex. the power?