performance chart of DC motor

Hi all,
I have a basic question about performance of DC brushed motor.
View attachment 48vccw.jpg
This is a topical performance chart of DC motor. I wonder why it lacks chart for lower revolution range.
Torque curve of DC motor is liner. So, is it for estimating rest of the chart by yourself?

Thanks

They have chosen to plot the curves with the X axis showing torque. This allows all the other parameters to be displayed and compared to the torque needed to drive any given load. The manufacturer (Mars Electric) has chosen to display the data for a constant applied voltage of 24V, which is why the RPM doesn't vary much; they probably have plots for other applied voltages if you ask them.

You can derive any other data you need from this plot, by doing some fairly simple calculations, or by reading straight from the graph. For example, motor losses can be determined from the change in motor rpm with load, Kv is simply the no load rpm divided by the applied voltage (in this case about 92, 2200 rpm / 24 volts), the torque constant can either be worked out from the Kv, or can be read directly from the graph, (110 lb-in at 120 amps, so about 1.09 A/lb-in). Once you have these figures you can go about matching the motor to your needs.

Jeremy

Hi Jeremy,
Thank you for your advise.

Here is the charts of the motor under various voltage;
http://www.cloudelectric.com/ProductDetails.asp?ProductCode=MO-ME-0909&Show=TechSpecs

Obviously. shape of the chart are almost same even @24V and it is just a small part of all the performance.
Now, I guess it may be because the bench tester limits torque range to be measured.
Anyway it is calculable if the motor really performs according to the theory in rest of the rpm range.

But, if so, another question comes to me....starting current may be more than 4 times of max current in the chart (about 160Amps in this case) that seems not be acceptable for most controllers nor cables, fuses ....

For example, here is a kit for the Mars motor; http://www.cloudelectric.com/ProductDetails.asp?ProductCode=PK-M909-K300P
The included fuse is for 300A, and Kelly controller limits within just 200A for max(80A continuous) that is far from starting current( estimated more than 600A).
So, I guess real performance of the motor in low rpm range is not like one calculated in theory.
Or, are there any mistake in my calculation?

Taichi