Steam engines and electric motors tend to produce maximum torque close to zero rpm with the torque diminishing as rotational speed rises due to increasing friction and other constraints.
Electric motor rpm torque curve.
Torque in imperial units can be calculated as.
Relationship between torque power and energy.
N revolution per minute rpm alternatively.
T inlb torque in lb f.
For example the ac motor found in the tesla roadster 2008 produces near constant maximum torque from 0 to about 6000 rpm while maximum power occurs at about 10000 rpm long after torque begins to drop off.
This is the opposite coefficient of the linear speed torque curve.
The roadster s redline is 14000 rpm.
Figure 1 provides a graphical illustration of these changes.
The linear model of a d c.
As a current flows through the electric motor a related electrical charge causes an armature to rotate.
One is a plot of empirical data and the other was plotted mechanically using a device developed at mit.
By overlaying the torque speed curve of a pump and a motor one can verify that the motor is producing enough accelerating torque to drive the pump to full speed as shown below.
1 ft lb f 1 356 nm.
The torque speed curves shown below are actual curves for the green maxon motor pictured at right used by students in 2 007.
Reciprocating steam engines and electric motors can start heavy loads from zero rpm without a clutch.
Motor torque speed curve is a very good approximation.
Thankfully in electric motors maximum torque is produced from the get go.
Usually in rpm v.
That is why the shaft and frame of a 900 rpm motor are usually larger than those of an 1 800 rpm motor of the same hp.
Speed torque gradient.
T ftlb p hp 5252 n 1b.
In this overlay the shaded area reflects the accelerating torque available from the motor to drive the pump.
T inlb p hp 63025 n 1.
T ftlb torque lb f ft.
Electrical motor power velocity and torque equations.
Like pumps motors produce a torque speed curve of their own.
P hp horsepower delivered by the electric motor hp.