The Geometry of Installation: Mounting Standards Explained

Imagine waiting 4 weeks for a specialized 20HP motor to arrive at your factory in Pune, only to realize the mounting holes don't match your machine. It's a nightmare scenario that happens more often than you think. In the electric motor world, "close enough" doesn't exist.

In the Indian market, we strictly follow IEC 60034-7 standards for mounting arrangements. This guide will help you speak the language of "B3", "B5", and "B14" fluently, ensuring you order the right Sun Star Motor every single time.

Decoding the Code Structure

Mounting codes usually start with "B" (for Horizontal Shaft) or "V" (for Vertical Shaft). Let's break down the most common ones found in Indian industries.

1. B3 – Foot Mounted (IM 1001)

The Standard Workhorse.

Description: The motor body has two feet (legs) welded or cast onto it. The shaft is horizontal.
Applications: Compressors, Pumps on base plates, Belt-driven fans, Conveyors.
Critical Dimensions:
- H (Center Height): Distance from the ground to the center of the shaft. (e.g., Frame 132 means center height is 132mm).
- A & B: The distance between mounting holes (width and length).

2. B5 – Flange Mounted (IM 3001)

The "Big Flange".

Description: No feet. The motor is held by a large circular flange on the drive end. The flange has through-holes (non-threaded) for bolts to go through into the machine.
Visual ID: The flange diameter is usually larger than the motor body diameter.
Applications: Direct coupling to Gearboxes, Hydraulic pumps, Agitators.
Critical Dimension: The PCD (Pitch Circle Diameter) of the holes and the Spigot (Rabbit) diameter.

3. B14 – Face Mounted (IM 3601)

The "Small Flange".

Description: No feet. The motor is held by a flange on the face, but unlike B5, the holes are threaded (tapped) on the motor face itself. You screw bolts *into* the motor.
Visual ID: The flange diameter is usually smaller than or equal to the motor body.
Applications: Small pumps, Textile machinery, Compact machine tools.
Confusion Alert: This is the #1 source of ordering errors. People see a round face and assume B5. Always check if the holes are proper holes (B5) or threaded blind holes (B14).

4. B35 – Foot + Flange (IM 2001)

The Hybrid.

Description: Has both feet (B3) and a large flange (B5).
Why? It offers extreme versatility. Sometimes the feet support the weight, and the flange aligns the load. Or strict alignment is needed while the feet reduce vibration stress.

Vertical Mountings (V1 vs V3)

If you are mounting the motor vertically (shaft up or shaft down), can you just use a B5 motor? Not always.

V1 (Shaft Down): Standard B5 motor simply turned down? Usually yes, BUT for large motors, you need reinforced bearings to handle the rotor's axial weight. And you need a "Rain Canopy" (cowling) on top to prevent water from entering the fan.
V3 (Shaft Up): Used in some cooling towers. Requires special sealing to prevent water running down the shaft into the motor.

Ordering Checklist for buyers

When contacting Sun Star Motors™ for a replacement, provide:

Frame Size: (e.g., 90L, 132M)
Mounting Code: (e.g., B3, B5)
Photo of Nameplate: Essential.
Photo of Face: If it's flange mounted, a quick phone photo helps us distinguish B5 from B14 instantly.

Conclusion

Mounting isn't just about utility; it's about stability. A B3 motor forced into a vertical application without bearing upgrades will fail prematurely. A B14 incorrectly ordered as B5 won't even bolt on. Take the extra minute to verify the code, and you'll save weeks of downtime.

Choosing the Right Motor: Foot vs Flange Mounting Guide