# 12VDC motor specification question *Need Help*

In summary, Part A requires 23.34lb.ft. (31.644 Nm) of torque at 3600 RPM to function. Part B is a slave motor, 12VDC (or BLDC). The main question is whether it is possible to achieve the required torque rating using Part B. The calculations for a 1/4 HP motor at 450 RPM with an 8:1 gear ratio are right on target, but finding a motor with these specifications has proven to be challenging and expensive. The 12V power supply for Part B cannot be changed. However, alternative options are being explored to meet the torque requirements for Part A and power Part B with a DC voltage of 24V or lower.

Here is some basic information:

Part A requires 23.34lb.ft. (31.644 Nm) of torque @ 3600 RPM to function.

Part B is a slave motor, 12VDC(or BLDC).
This inquiry is specifically directed at Part B:

Is it possible to achieve the target required torque rating using Part B?
I have calculated 1/4 HP motor @450RPM, with an 8:1 G.R. to be 23.3416, which is right on target, but finding this motor has proven to be extremely challenging (custom built motor of this spec is over 10K USD *yikes*), so I wanted to reach out an see if there were any other options I can explore (and afford) to reach my target using this motor setup(i.e.-type, RPM, torque rating, G.R.)

Part A is fixed and cannot be changed, as is the power supply in Part B

Thanks for any help.

Welcome to PF.

I'm getting 16hp for your power requirement there, not 1/4. You might want to check your calc (I think you multiplied the torque instead of dividing it!). And I think the difficulty might be with the power supply: 12V is awfully low for such a horsepower (heck, it's low even for 1/4 hp). Why the 12V limit?

I should clarify:
Part A requires 16hp (23.34lb.ft.) @ 3600 Rpm.

16HP * 5252 / 3600 = 23.34222 lb.ft.

The calculations on Part B were using 1/4HP @ 450 RPM, 8:1 G.R.
Meaning:
.25 * 5252 / 450 = 2.91777lb.ft.
At an 8:1 G.R., that would mean 2.917 * 8 = 23.336lb.ft.
450 RPM * 8 = 3600 RPM final.

Also another question, am I correct on the assumption that torque travels through a set gear ratio?
Ex: 2.917lb.ft. for the above stated 1/4HP motor, at 8:1 gearing, would be the 2.917lb.ft. * 8 on the final drive, producing the required 23.336lb.ft.?

The 12v power source is part of how I have this device prepped to run, and although I may be able to use a 24v, it remains DC. The 12vdc is only used to run Part B, which in turn will link into rotating Part A.

It is Part B that I am having a major issue with finding a usable motor. I would be willing to consider another alternative, so long as the final requirements of Part A are met in entirety and Part B is powered from DC </=24V

Last edited:
I should clarify:
Part A requires 16hp (23.34lb.ft.) @ 3600 Rpm.

16HP * 5252 / 3600 = 23.34222 lb.ft.
Ok, agreed.
The calculations on Part B were using 1/4HP @ 450 RPM, 8:1 G.R.
Meaning:
.25 * 5252 / 450 = 2.91777lb.ft.
At an 8:1 G.R., that would mean 2.917 * 8 = 23.336lb.ft.
450 RPM * 8 = 3600 RPM final.
An 8:1 gear ratio will multiply the torque and divide the rpm. You can't turn 1/4 hp into 16 hp with gears.

You should read the wiki on gearing: http://en.wikipedia.org/wiki/Gear
Also another question, am I correct on the assumption that torque travels through a set gear ratio?
Ex: 2.917lb.ft. for the above stated 1/4HP motor, at 8:1 gearing, would be the 2.917lb.ft. * 8 on the final drive, producing the required 23.336lb.ft.?
A 1:8 gear ratio will multiply the torque by 8 but an 8:1 will divide it by 8.
The 12v power source is part of how I have this device prepped to run, and although I may be able to use a 24v, it remains DC. The 12vdc is only used to run Part B, which in turn will link into rotating Part A.

It is Part B that I am having a major issue with finding a usable motor. I would be willing to consider another alternative, so long as the final requirements of Part A are met in entirety and Part B is powered from DC </=24V
Voltage is not difficult to change, so I don't understand why it would be such a hard constraint. You may not have any choice here - what you are trying to do may not be possible.

Based on the information provided, it is possible to achieve the required torque rating using Part B. The calculated 1/4 HP motor at 450 RPM with an 8:1 G.R. is a suitable option for meeting the torque requirement. However, it may be difficult to find a pre-made motor with these exact specifications, as you have mentioned. In this case, you may need to consider custom-building the motor or exploring other motor options that may be more affordable while still meeting the required torque rating. It is important to keep in mind that the power supply in Part B is fixed and cannot be changed, so any alternative motor options should be compatible with the power supply.

## 1. What is the voltage requirement for a 12VDC motor?

The voltage requirement for a 12VDC motor is 12 volts, as indicated in its name. This means that the motor will operate most efficiently when supplied with a DC power source of 12 volts.

## 2. What is the maximum current rating for a 12VDC motor?

The maximum current rating for a 12VDC motor can vary depending on the specific motor and its intended use. However, most 12VDC motors have a maximum current rating of around 2-3 amps.

## 3. What is the torque rating for a 12VDC motor?

The torque rating for a 12VDC motor can also vary depending on the motor's design and purpose. Generally, these motors have a torque rating of around 1-3 Nm (Newton-meters).

## 4. What is the speed rating for a 12VDC motor?

The speed rating for a 12VDC motor can also vary greatly depending on the specific motor and its intended use. However, most 12VDC motors have a speed rating of around 3000-5000 RPM (revolutions per minute).

## 5. What is the power rating for a 12VDC motor?

The power rating for a 12VDC motor is determined by multiplying the voltage (12 volts) by the current (usually between 2-3 amps). This means that the power rating for a 12VDC motor is typically around 24-36 watts.