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Cast iron worm speed reducer with 56C C-face input and round output shaft

Boston Gear

Boston Gear F721-20-B5-G Speed Reducer 56C 20:1

SKU CH-SQ2D-9MHKJ

A cast-iron worm speed reducer with a 20:1 ratio, 56C C-face input and 590 in-lb output torque

  • 20:1 gear ratio reduces output speed to 88 RPM
  • 590 in-lb maximum output torque handles heavy loads
  • Cast iron housing provides durable worm gear enclosure
  • 56C C-face mounting fits standard motor frames directly
  • Any-angle mounting orientation allows flexible installation positions

Application Fit

The Boston Gear F721-20-B5-G is a worm-gear speed reducer built for a 56C motor frame and a 20:1 ratio. It suits equipment that needs 88 RPM output and up to 590 in-lb of torque from a 1 hp input. Buyers who need a different ratio, a higher input speed or a hollow output shaft should look elsewhere.

Accessory Impact

The unit ships as a standalone reducer with a cast-iron housing and tapered roller bearings. No mounting hardware, lubricant or coupling is included, so the installer must supply bolts, the correct oil grade and a compatible input coupling. Overhung load capacity is rated at 150 lb for the output shaft.

Interface Limits

The C-face input mounts directly to a 56C frame motor, fixing the bolt pattern and pilot dimensions. The worm center distance is 2.06 in and the base-to-center height is 2.28 in, which determines the footprint and shaft height in the drivetrain. Rotation can be clockwise or counter-clockwise, but the ratio and centre distance are not field-adjustable.

Highlights

  • 20:1 gear ratio reduces output speed to 88 RPM
  • 590 in-lb maximum output torque handles heavy loads
  • Cast iron housing provides durable worm gear enclosure
  • 56C C-face mounting fits standard motor frames directly
  • Any-angle mounting orientation allows flexible installation positions

Specifications

BrandBOSTON GEAR

Questions about this item

How often does the worm-gear oil need changing in the F721-20-B5-G?

The unit is factory-filled with synthetic lubricant rated for the life of the reducer; no scheduled oil changes are required under normal 88 RPM output operation.

What stops continuous duty at the 1 hp input rating on the 56C frame?

The 590 in-lb output-torque limit and 150 lb overhung-load capacity are the first constraints reached during sustained 20:1 reduction.

How hot does the cast-iron housing get when the reducer runs all day at 20:1?

Cast-iron construction and tapered-roller bearings dissipate heat from the 1 hp input so surface temperature stays within normal industrial limits for worm-gear units.

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