What Is the Difference Between B3, B5 and B35?
The main difference is how the motor attaches to the equipment. IM B3 uses mounting feet, IM B5 uses a large mounting flange without feet, and IM B35 combines mounting feet with a large flange. These designations describe horizontal-shaft arrangements.
Choosing the correct arrangement is only the first step. The shaft, mounting interface and available installation space must also match the driven equipment. Two motors with the same power rating are not necessarily mechanically interchangeable.
B3, B5 and B35 at a Glance
| Mounting Arrangement | Configuration | Main Interface to Check |
|---|---|---|
| IM B3 | Foot-mounted, without a mounting flange | Shaft centre height, foot-hole spacing, fixing holes and shaft dimensions |
| IM B5 | Large-flange-mounted, without mounting feet | Flange register, bolt circle, fixing holes, flange diameter and shaft dimensions |
| IM B35 | Foot-mounted with a large mounting flange | Both foot and flange dimensions, together with shaft dimensions and alignment requirements |
IM B3: Foot-Mounted Motors
A B3 motor is secured through its feet to a baseplate, machine bed or supporting structure. This arrangement can be used where the motor and driven equipment are supported on a base and connected through a suitable coupling or transmission.
For a replacement, check the shaft centre height and the mounting-hole positions in both directions. Also confirm the distance from the shaft shoulder to the mounting interface, rather than checking the foot spacing alone.
IM B5: Flange-Mounted Motors
A B5 motor connects through a large flange at the drive end. The mating equipment must have a compatible flange interface, including the locating register and bolt pattern.
A flange that looks similar in a photograph may still have a different register diameter, bolt circle or shaft extension. Request the dimensional drawing before confirming compatibility. B5 should not be confused with the smaller-flange B14 arrangement.
IM B35: Foot-and-Flange-Mounted Motors
A B35 motor has both mounting feet and a large flange. It is selected where the equipment design calls for this combination.
Both interfaces need to agree with the machine layout. The feet and flange must not be forced into position to compensate for dimensional or alignment errors. Follow the motor and equipment installation instructions when securing the assembly.
Which Dimensions Should You Compare?
Shangli’s catalogue includes mounting and overall-dimension drawings for multiple motor series. Use the drawing for the exact series, frame and configuration being considered, rather than borrowing dimensions from another product family.
| Dimension Group | Checks Before Ordering |
|---|---|
| Shaft | Diameter, extension length, key and keyway dimensions, and the position of the shaft shoulder |
| Mounting Feet | Shaft centre height, transverse and longitudinal hole spacing, fixing-hole size and foot position |
| Mounting Flange | Outside diameter, locating register diameter and depth, bolt-circle diameter, and hole number and size |
| Overall Envelope | Motor length, width, height and clearance around the terminal box and cooling-air openings |
| Interface Details | Dimensional tolerances, coupling fit, cable access and equipment-specific requirements |
Compare the dimensions using the reference points and symbols on each drawing. A nominal frame designation or mounting code does not replace a complete dimensional check.
Do Not Overlook Shaft Orientation
A horizontal mounting designation should not be used as approval for vertical operation. If the motor shaft will point upwards or downwards, state this clearly in the enquiry. The appropriate mounting designation and suitability of the motor must be confirmed.
Changing the orientation may require a review of bearing loads, lubrication, drainage and protection against water entry. Do not assume that a motor can be rotated into a different operating position without further checks.
Common Motor Replacement Mistakes
Matching power and speed while overlooking shaft or mounting dimensions.
Assuming all motors with the same frame designation have identical overall dimensions.
Selecting a flange by its outside diameter without checking the register and bolt circle.
Leaving insufficient space for the terminal box, cable connections or cooling airflow.
Assuming a mounting arrangement shown for one series is available across every series and frame size.
What to Send with Your Enquiry
For mounting confirmation, send a clear nameplate photograph, the existing motor drawing if available, and photographs of the equipment connection. Include the required mounting code, shaft orientation and any space restrictions.
If there is no drawing, provide measured shaft, foot and flange dimensions and identify any approximate values. Final compatibility should be confirmed against the proposed motor drawing before ordering.
Send your requirements to [email protected] so the Shangli team can review the mounting arrangement for your application.