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Cast iron worm gear speed reducer with 56C motor flange, 25:1 ratio

Boston Gear

Boston Gear F718-25-B5-G Speed Reducer 25:1 56C

SKU CH-G3A1-ZG2GY

A worm-gear speed reducer with a 25:1 ratio, 56C C-face input, 70 RPM maximum output speed, 0.5 hp input rating, 350 in-lb output torque and 150 lb overhung load capacity

  • Delivers 350 in-lb output torque for heavy loads
  • 25:1 ratio reduces speed to 70 RPM maximum
  • 5 hp input rating matches 56C motor frames
  • Cast iron housing with tapered roller bearings resists wear
  • Mounts at any angle for flexible installation

Speed Reducer 25:1 56C

The Boston Gear F718-25-B5-G is a worm-gear speed reducer with a 25:1 ratio designed for 56C-frame motors. It accepts a C-face input and delivers a maximum output speed of 70 RPM with up to 350 in-lb of torque. The unit suits industrial machinery requiring right-angle power transmission in a compact cast-iron housing.

C-Face Mounting And Orientation

The reducer mounts at any angle using the standard 56C motor flange, simplifying alignment for maintenance teams. Overhung load capacity is rated at 150 lb, so excessive radial force on the output shaft can reduce bearing life. The tapered roller bearings and hardened steel gears tolerate bidirectional rotation, but improper shimming during motor installation may introduce noise or premature wear.

Worm-Gear Efficiency Limits

Worm gearing inherently limits efficiency compared to helical or planetary types, generating more heat under continuous duty. The 1.75-inch centre distance and 2.06-inch base-to-centre dimension fix the envelope, restricting retrofit options where space is tight. Maximum input power is capped at 0.5 hp, so applications demanding higher throughput will need a larger frame size.

How it compares

Measured against everything we stock in Transmission Fluid & Gear Oil, at today’s prices. Recalculated every night.

Price $562.99
Pricier than about 81% of the 118 comparable items (median $40.99).

Specifications

Product
Brand nameBOSTON GEAR

Questions about this item

How do I confirm the F718-25-B5-G speed reducer is running correctly after installation?

Verify the output shaft turns at or below 70 RPM under load, check that input power does not exceed .5 hp, and ensure output torque stays within the 350 in-lb rating.

What comes with the reducer and what must I supply separately?

The unit includes the cast-iron housed worm gear assembly with 56C C-face input and round output shaft; you must provide the motor, mounting hardware, and lubricant.

Which gear ratio should I select for my application?

This model is fixed at a 25:1 ratio; choose it when you need a 25-to-1 speed reduction with up to 350 in-lb output torque.

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