From Horsepower to Watts to Newton Metres

Did you know that when galloping a horse has twenty horsepower, but when walking normally only two thirds of that? Horses would be amazed! In the case of cars, horsepower – with which we have long been familiar – has been replaced by kilowatts. Naturally we still look for the HP figure. What engine engineers are interested in, on the other hand, are Newton metres. Why is that so? And why are Newton metres so important when it comes to pneumatic motors?

The speed of a sports car versus the pulling power of a truck Appliance manufacturers often indicate performance in watts.

Device manufacturers often state power in watts. The specified wattage expresses the maximum power. In fact, this maximum performance is only achieved under ideal conditions. However, statements about performance and efficiency under operating conditions can only be derived from the wattage to a limited extent. The bite of a machine is therefore primarily based on torque and speed. The higher the torque, the more powerful a machine grabs. If it does it from the start, i.e. also in the lower speed range, you are dealing with a powerful engine. It also happens that a high-torque 600 PS truck can pull more than a 600 PS sports car. You have to decide what you want: speed or work.

Why Newton meters? Force is mass times acceleration.

The torque is measured in Newton meters (Nm). The torque of 1 Newton meter arises when the force of 1 Newton acts on an axis of rotation with a lever length of one meter. 1 Newton is defined as follows: 1 Newton = 1 kg x m / s². This formula reads like this: If you move 1 kilogram by 1 meter per second, you generate 1 Newton. In physics, force is understood to mean mass times acceleration. Force is given today according to the International System of Units (SI - Système International d’Unités) in Newton. The relationship between force, mass and acceleration was first described by Isaac Newton (1643 - 1727).

Light compressed air supply hoses are important for sewer rehabilitation

The decisive factor for the compressed air motors used by Schwalm is the force - measured in Newton meters - that they develop from the lower speed range. A high wattage, on the other hand, only means that they consume a lot of compressed air. However, this means that the compressed air hose to supply the robot tools needs a large diameter. Milling work using robotics in the sewer requires light supply systems. Robots are hindered in their freedom of movement by heavy hoses. Long hose connections of up to 100 m and more are required in ducts. However, the operating pressure drops with increasing hose length. Air motors with high air consumption and high wattage are therefore not a good solution for robotics. The lowest possible air consumption is important for an air motor. Therefore, wattage, but force in Newton meters is the more interesting value for determining power.