D-FLANGE vs C-FLANGE
The pictures below show the difference between electric motor front flange mounting options.
There are two models that are the most popular. First, the D-FLANGE or B5, which usually has a larger diameter than the electric motor.
In addition, the D-FLANGE has four non- threaded holes (Picture 1). The second option is the C –FLANGE, or B14. The diameter is often very close to the outer size of the electric motor (Picture 2) and has four threaded holes.