# How Can A High-Torque Motor Have Low a low RPM

• 012anonymousx
In summary, Torque is the rotational force that causes acceleration in a motor. However, the amount of force does not necessarily determine the speed of the motor. Building a DC motor with a dense coil increases torque but decreases RPMs, while a looser coil increases RPMs but decreases torque. The torque and RPM ratio is also affected by the load connected to the motor. This means that a "high torque" motor without a load will not produce any torque.
012anonymousx
Torque is the rotational force.
If there is more force, how can the motor be slow?

I'm building a DC motor and read that given a constant amount of coil, creating a very dense coil will increase torque but lower RPMs.
Conversely, making it looser (bigger radius) increases RPM but lowers torque.

The torque gives you acceleration - but it is possible to accelerate to any speed... however slow.

For your motor - it will accelerate to a constant speed due to losses that are proportional to speed. This will be proportional to the amount of mass that has to be spun - and so is the torque.

The increase in torque at lower rpm is offset by increase in back emf at higher rpm, which decreases the torque at higher rpm.

Motors are connected to loads. The load determines the ratio between RPM and torque. If a "high torque" motor is not connected to a load and is just allowed to freewheel, it does not produce any torque.

I can explain this phenomenon using the equation for torque: T = rFsinθ, where T is torque, r is the radius of the coil, F is the force applied, and θ is the angle between the force and the lever arm (in this case, the radius of the coil).

In a high-torque motor, the radius of the coil is smaller, meaning that the force is applied closer to the center of rotation. This results in a higher torque, as the lever arm (radius) is smaller. However, because the force is applied closer to the center, the rotational speed (RPM) is lower.

On the other hand, in a low-torque motor with a larger radius coil, the force is applied further from the center of rotation, resulting in a smaller torque. However, because the force is applied further from the center, the rotational speed is higher.

Therefore, the density or tightness of the coil does not directly affect the torque or RPM of the motor. It is the radius of the coil that plays a crucial role in determining the torque and RPM of the motor.

## 1. How can a high-torque motor have low RPM?

A high-torque motor can have low RPM because torque and RPM are inversely proportional. This means that as torque increases, RPM decreases and vice versa. So, a high-torque motor will have low RPM and a low-torque motor will have high RPM.

## 2. What determines the torque and RPM of a motor?

The torque and RPM of a motor are determined by its design and the amount of power supplied to it. The motor's design, including the number of coils, size of the magnets, and the type of winding, affects its torque and RPM capabilities. The amount of power supplied to the motor can also be adjusted to control its torque and RPM.

## 3. Can a high-torque motor be used for high-speed applications?

No, a high-torque motor is not suitable for high-speed applications because it is designed to provide high torque at low speeds. Using it for high-speed applications can cause the motor to overheat and potentially damage it.

## 4. What are the advantages of a high-torque motor with low RPM?

A high-torque motor with low RPM is ideal for applications that require a lot of power or force, such as heavy machinery, vehicles, or industrial equipment. It can also provide smoother and more precise movements due to its lower speed.

## 5. How can the RPM of a motor be increased without sacrificing torque?

The RPM of a motor can be increased without sacrificing torque by using a gearbox or transmission. These mechanisms can increase the speed of the output shaft while maintaining the torque from the motor. Another option is to use a motor with a higher voltage, as this can also increase the RPM without sacrificing torque.

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