B3 vs B5 vs B35 Motor Mounting: How to Choose the Right Installation
B3, B5 and B35 describe the mechanical mounting arrangement of an IEC-style motor. A motor with the correct power but the wrong mounting, shaft or flange dimensions cannot be installed safely. Confirm the driven equipment drawing before requesting a replacement motor.
Information to confirm
- B3: foot-mounted motor; verify base-hole spacing, shaft height and shaft extension
- B5: flange-mounted motor; verify flange outside diameter, spigot, bolt circle and shaft length
- B35: foot-and-flange mounting; verify both the base and flange dimensions
- Frame size, shaft diameter, keyway and shaft extension
- Direction of mounting, cable-entry orientation and available service clearance
- Any special requirements for corrosion, outdoor use, brake motors or inverter operation
How to narrow the specification
Start from the actual duty point, not the equipment name alone. Check the driven load, transmission losses, operating environment and installation constraints together. Keep the nameplate requirements, mounting dimensions and local electrical supply in the enquiry so the recommended configuration can be checked before order.
Request a technical quotation
Send the existing nameplate and mounting drawing for a matched quotation from our industrial motor collection. You can also use the Motor Sizing Tool for an initial power recommendation.
For a preliminary recommendation, submit the operating conditions and any drawing or nameplate photo. Final selection must be confirmed against the complete application.