40 HP Gearbox RW-300, Smooth 1-3/8" Input Shaft


$140.99 EA

With a rated horsepower capacity of 40, this gearbox will provide an excellent operation to your rotary cutter. It has a smooth input shaft that measures 1-3/8 inches. This rotary gearbox may be used with 4 foot, 5 foot, and 6 foot rotary cutters.

Availability: In Stock -

Gearboxes work to administer a transfer of speed and torque through their internal gear rotation, helping the overall performance of your rotary cutter. This RW-300 gearbox operates at 40 HP. The housing is constructed from durable ductile iron and the smooth input shaft measures 1-3/8 inches. It has a beveled type of gear, with the gear ratio measuring 1:1.47. Designed for use with 4 foot, 5 foot, and 6 foot rotary cutters, this rotary cutter gearbox has 4 bolt holes measuring 5/8 inch on a 6-3/4 inch bolt circle for installment.


  • Gearbox RW-300
  • Horsepower: 40
  • For 4 ft., 5 ft., and 6 ft. rotary cutters
  • Come with the castellated nut and the carrier hub for the stump jumper (if needed)
  • Housing construction: Ductile iron
  • Smooth input shaft: 1-3/8 in.
  • Gear ratio: 1:1.47
  • Gear type: Bevel gear
  • Bolt pattern: (4) 5/8" diameter holes on a 6-3/4 in. bolt circle
  • Output shaft 1-1/2 in. 12 Spline
  • For castle nut use ASC # 102241 - 1" Castle Nut
  • For output shaft gearbox seal RW300 use # 89757
  • For input shaft gearbox seal RW300 use #89756

Check out our selection of Rotary Mower Parts & Gearboxes

  40HP GEARBOX SMOOTH INPUT SHAFT in Rotary Mower Parts and Farm Machinery Parts at Agri Supply ®.

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Review Summary (Based on 3 Reviews)


Customer Reviews

5 Stars 5' King Kutter

PirateKevinNC from NC wrote (October 20, 2020):

This replacement gearbox worked perfectly on my bush hog.

5 Stars gearbox rw-300

Elton Kramer from OR wrote (May 23, 2019):

received it today.installed it on 5 ft. brush hog works great. great price. Works great. Thank you.

5 Stars Great Replacement

J. Duffy from SC wrote (August 01, 2017):

Gearbox fit my older Pittsburgh Field General perfect. Box came with new output castle nut which wasnt clear in the description. Dont forget to fill it with 90 weight oil before you run it.

CategoryNumber: 1900059