What is the difference between NMRV and NRV reducer?

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Learn the key differences between NMRV and NRV worm gearboxes. NMRV features flange input for direct motor mounting; NRV uses shaft input without flange. Find out which fits your application

H1: NMRV vs NRV Worm Gearbox – What‘s the Difference?

Both NMRV and NRV are RV-series worm gear reducers with identical internal gearing, housings, and performance. The only difference is the input configuration

H2: NMRV – Flange Input (Hollow Bore with Flange)

NMRV stands for hole input with flange. The input features a hollow bore with a pre-mounted flange (B5 or B14) designed for direct IEC motor mounting.

Best for: Direct motor coupling – motor shaft slides into the hollow bore and bolts to the flange

H2: NRV – Shaft Input (Without Flange)

NRV stands for shaft input without flange. The input is a solid input shaft – no flange for motor mounting.

Best for: Belt/pulley drives, chain drives, or coupling connections where motor is mounted separately

Common use: Applications requiring flexible motor positioning or where direct flange mounting

 isn‘t suitable

H2: Quick Comparison

Feature	NMRV	NRV
Input type	Hollow bore + flange	Solid shaft (no flange)
Motor mounting	Direct bolt-on (B5/B14)	Coupling, belt, or chain drive
Best application	Geared motor units	Flexible drive arrangements
Housing	Aluminum / Cast iron	Aluminum / Cast iron
Output options	Solid / Hollow shaft	Solid / Hollow shaft

H2: How to Choose

Choose NMRV if: You want to mount the motor directly onto the gearbox – clean, compact, and simple.

Choose NRV if: You need flexible motor positioning, are using belt or chain drives, or your motor doesn‘t have a standard IEC flange.

H2: FAQ

Q: Are NMRV and NRV gearboxes interchangeable?
A: The gearbox body is the same – only the input differs. You cannot convert one to the other without replacing the input housing.

Q: Which one is more common?
A: NMRV is more popular for standard geared motor applications. NRV is preferred for custom drive arrangements.

Q: Do they have the same performance?
A: Yes – same ratios, torque ratings, efficiency, and self-locking capability. The difference is purely mechanical input configuration.

Q: Can I mount a motor on an NRV?
A: Yes – but you‘ll need a coupling or belt/pulley system. You cannot bolt the motor directly to the gearbox.

NMRV for direct motor mounting, NRV for flexible drive arrangements.