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• Ben Seaman

# Weight Impact on Motor Torque and Road Incline

When designing a motor system for an application, it is important to consider the weight of the load being driven and the incline of the road surface. These factors can have a significant impact on the torque requirements of the motor and therefore the sizing of the motor.

## Guiding principle of Static Torque

The concept of static torque can be expressed as the product of tractive effort and tire radius. Static torque (in Newton meters or Nm) refers to the twisting force that is exerted on an object that is not in motion. In the context of vehicles, this torque can be used to measure the force that is required to turn the wheels of a stationary vehicle, and is affected by the tractive effort (in Newtons or N) applied to the tire, as well as the radius (in meters or m) of the tire. This formula can be useful in analyzing the performance of vehicles or determining the appropriate specifications for a particular application.

Static torque (Nm) = Tractive effort (Ft) x tire radius (r)

## Vehicle Weight

Firstly, let's consider the effect of weight on the torque requirements. The torque required to move a load is proportional to the weight of the load, the slope of the road surface, and inertial and friction forces resisting motion. This torque requirement is known as the static torque.

Now let's consider the effect of road incline on the torque requirements. When starting up an incline, the effect of gravity acting on the load increases, which increases the torque required to move the load. The torque required to move a load up an incline can be calculated using the static torque formula. The total torque required by the motor system will be the sum of the vehicle forces times the driven tire radius to move the vehicle up the incline. It is important to select a motor that can provide the required torque for the application, taking into account any safety factors or margin of error.

In summary, the weight of the load and the incline of the road surface can have a significant impact on the torque requirements of a motor system. It is important to accurately calculate the static torque and the torque required to move up the incline in order to size the motor appropriately. Failure to do so can result in an underpowered motor system that may not be able to move the load or drive up inclines effectively, or an overpowered motor system that is more expensive than necessary.