Boston Gear F721-20-B5-G Speed Reducer 56C 20:1
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.
How it compares
Measured against everything we stock in Transmission Fluid & Gear Oil, at today’s prices. Recalculated every night.
- Price $636.99
- Pricier than about 90% of the 118 comparable items (median $40.99).
Specifications
| Product | |
|---|---|
| Brand name | BOSTON 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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