Motovario B103 12.05:1 Bevel Gearbox – 50mm Bore, 90B5

Overview

B103 12.05:1 bevel helical gearbox with a 50mm hollow bore output and 90B5 IEC motor input for compact 90° right-angle drive integration.

Engineered for continuous-duty operation, this configuration delivers dependable torque transfer and smooth running under load.

Mid reduction: This mid reduction ratio delivers a balanced speed-to-torque profile, supporting steady running under load for conveyors, general handling systems, and continuous-duty machinery.

Built for long service life, this gearbox supports consistent performance for automation and materials handling duties.

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Need the non-standard 45mm bore option?

If your application requires a 45mm output bore instead of the standard 50mm, we can supply this as a non-standard configuration. View available B103 options and request the 45mm version here: Motovario B103 Gearbox.

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Key Specifications

• Series: B Series – Bevel Helical Gearboxes
• Model: B103
• Reduction Ratio: 12.05:1
• Output Bore: 50mm Hollow Bore
• Motor Input: 90B5 IEC Flange
• Housing Material: High-strength cast iron
• Gear Type: Spiral bevel + hardened helical stage
• Mounting Positions: B3 Horizontal Mount
• Duty Rating: Suitable for continuous industrial operation (S1)

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Output Speed (4-Pole vs 2-Pole Motors)

Calculated nominal output speed using a standard IEC motor:

Motor Type	Input Speed (rpm)	Estimated Output Speed (rpm)
4-Pole	1400	~116 rpm
2-Pole	2800	~232 rpm

Need torque confirmation? Output torque depends on motor power (kW), gearbox efficiency, and service factor. Use our Gearbox Service Factor Calculator or contact us for verified torque figures.

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Motor Input Chart (IEC Flange Details)

This gearbox is supplied with a 90B5 IEC motor input. Confirm flange compatibility below:

Motor Input	IEC Standard	Input Dimensions
90B5	IEC 60072 / IEC 60034 (B5 flange)	Ø200 × 24

If you’re unsure whether your motor is B5 or B14, contact our technical team for compatibility confirmation.

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Internal Links & Compatible Options

Same ratio, different motor input: jump to the B103 12.05:1 variant you need (50mm bore).

Need a different ratio? Explore the closest B103 50mm bore ratios above and below this version.

More B103 options: Browse all Motovario B103 gearbox ratios

Explore the full B Series range: Motovario B Series bevel gearboxes

Helpful calculators:
Gearbox Ratio & Speed Calculator |
Output Torque Calculator

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Performance & Design Features

✔ Space-saving 90° bevel layout for compact machine designs
✔ Strong torque multiplication with stable, controlled output speeds
✔ Precision-machined spiral bevel gearing for smooth, low-noise power transfer
✔ Heavy-duty taper roller bearings for high radial and axial load handling
✔ Well suited to inverter (VFD) driven motors and variable-speed control
✔ Rigid cast iron housing built for OEM and continuous-duty operation

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Ratio Selection Tips

• Best for: applications that need a quicker output speed with modest torque gain — such as faster conveyors, packaging infeed/outfeed, and indexing where responsiveness matters.
• Selection tip: low ratios suit responsive motion — check acceleration/inertia and ensure the driven equipment doesn’t require very slow output speed.

FAQ

Will this ratio be too fast for my application?
If you need very slow output speed, move up to a mid or high reduction ratio. Low ratios are best when you still want a relatively quick output with torque gain.

Can I run this with a VFD?
Yes — a VFD is ideal for fine speed control. Keep an eye on cooling at very low motor speeds if you reduce frequency for extended periods.

Configuration Notes

• Input flange note: the 90B5 flange option supports larger IEC motors where extra input torque capacity is required without changing the right‑angle installation layout.
• Output bore note: with a 50mm bore, this gearbox suits many standard shafting setups, providing a robust interface for continuous-duty power transfer.
• Application example: fast conveyor infeed/outfeed where you want responsive line speed without sacrificing pulling force.

Typical Applications

• Conveyor and line-shaft drive systems
• Automated production and assembly lines
• Food and beverage processing machinery
• Materials handling and logistics equipment
• Pumps, mixers, and agitator drives
• OEM machine and equipment builds

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Need help selecting the correct ratio, bore size, or motor input?
Contact our gearbox specialists for sizing assistance, torque verification, and availability confirmation.