Electric motor problems: What is soft foot?

Our 45 years’ experience of repairing and rewinding electric motors means we’ve seen it all when it comes to motor faults, and soft foot is no exception. But what is soft foot, why does it occur and how does it affect your motor-driven process. Read on for all the answers.

What is soft foot?

Soft foot refers to the non-parallel alignment between an electric motor’s foot and the mounting base. Some compare it to a chair having one leg shorter than the other, resulting in a wobbling motion when it’s sat on. Soft foot differs in that the foot actually touches the mounting base, but is not ‘flush’ and therefore does not make a uniform amount of contact.  

What causes soft foot?

Causes of soft foot include:

• Dirt or debris lodged under the motor feet
• Damage or flaws in motor feet or mounting base
• Incorrect size or number of shims under motor feet
• Bolts excessively tightened, leaving feet warped.

What are the effects of soft foot?

Soft foot results in the motor’s shaft being misaligned, which can cause serious issues when machinery is put into service. That’s because correct shaft alignment between a motor and the driven machinery is critical for efficient and reliable performance and even slight misalignment will result in excessive stress and wear on shafts and bearings, almost certainly leading to premature equipment failure.

How do I avoid soft foot?

Here are some tips for removing the problem of soft foot:

• Tighten feet bolts in sequence, following the same pattern every time
• Ensure the feet and mounting base are clean and free of debris
• Check for dents and burrs
• Make sure shims are clean and perfectly flat
• Use laser alignment equipment to be certain shafts are level with each
        other.

If you’re concerned that soft foot may have already damaged your electric motor and/or the driven machinery, our motor rewinds team are here to help. We’ll collect and deliver your motor free within a 50-mile radius of our workshop in Tollesbury Essex, and we have an emergency next-day service available if required. We’ll always offer an honest appraisal when we receive the motor, and if it’s cheaper for you to replace it rather than have it repaired, we’ll tell you.

So if you’d like a quote for a repair or rewind, or to enquire about a replacement motor, call our friendly team on 01621 868138 or email info@gibbonsgroup.co.uk.