VEX Robotics will be closed in observance of Thanksgiving on Thursday, November 22nd, and Friday, November 23rd. Our office will re-open on Monday, November 26th.

Be advised that FedEx will be closed for delivery on Thursday, 11/22. For example, a Next-Day Air order placed by 2:00 PM CST on Wednesday, 11/21, will be delivered on Friday, 11/23. Orders placed after 2:00 PM CST on Wednesday will process and ship out Monday, 11/26, to then be delivered according to the selected shipping speed.

We appreciate your understanding and wish all VEX users a happy holiday!

Single Reduction Clamping Gearbox

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Single Reduction Clamping Gearbox


The Single Reduction Clamping Gearbox achieves versatility through its simplicity. This gearbox uses four bolts to clamp onto a piece of 1" x 2" VersaFrame tube - no precision machining needed. Once mounted, it mounts a CIM-style motor offset from a bearing block on a perfect 84-tooth gear spacing. Use this efficient setup to drive an upper mechanism with ease, or combine multiple gearboxes to create a smooth-running, lightweight VersaChassis.

  • Simple design for quick assembly and maintenance
  • Variety of gearing options
  • Combines with the Plastic Bearing Block for a second stage reduction

Availability: In stock



The Single Reduction Clamping Gearbox naturally pairs with a Plastic Clamping Bearing Block or VersaBlock to establish a standard drivetrain gear reduction (see the Bearing Block Spacing drawing for details). For those who wish to use a 6" wheel, VEXpro HTD belts & pulleys can be used to achieve the same result. Download the STEP file for this Application Example here.

Single Reduction Clamping Gearbox with 6 in. Wheel

This chart explains the gearing options for the Single Reduction Clamping Gearbox paired with the Plastic Clamping Bearing Block. Refer to the Clamping Gearbox / Plastic Bearing Block drawing for detailed gear spacing.

Single Reduction Clamping Gearbox with Plastic Clamping Bearing Block
4" Wheel
Clamping Gearbox Plastic Bearing Block
(Stage 2)
Adjusted Output Speed
14:70 Not Used 15.01 ft/s
13:70 >(using center distance) Not Used 13.94 ft/s*
12:72 Not Used 12.51 ft/s*
11:72 (using 12t
center distance
Not Used 11.47 ft/s*
14:70 30:66 6.82 ft/s
12:72 30:66 5.69 ft/s
6" Wheel
Plastic Bearing Block
(Stage 2)
Adjusted Output
14:70* 30:66 10.24 ft/s*
12:72 30:66 8.53 ft/s
14:70 24:72 7.51 ft/s
12:72 24:72 6.26 ft/s
Kit Contents
    Single Reduction Clamping Gearbox (217-4156)
  • (1) Single Reduction Clamping Gearbox - Front
  • (1) Single Reduction Clamping Gearbox - Back
  • (4) #10-32 Jam Nut Nylock
  • (4) #10-32 X 1.375" Socket Head Bolt
Material Type
  • Glass Filled Nylon
  • 0.25 lbs
CAD Files