MAXPlanetary Gearbox System — REV-21-2100
Overview
Team 2890 uses the MAXPlanetary as their standard cartridge-based modular planetary gearbox. It’s designed specifically for NEO-class motors (NEO, NEO 550, Falcon 500, 775) and allows rapid gear ratio changes without redesigning the entire mechanism.
Key Features
- Cartridge-based design — swap gear ratios on the fly without rebuilding
- 27 gear ratios available — 2:1 to 125:1 by stacking cartridges
- Self-contained lubricated cartridges — no re-greasing on swap
- Three mounting options — face mount, side mount, or stacked
- 1/2in hex output shaft — compatible with standard FRC hex bearings
- MAXSpline output — integrates with REV ION system
- Assembly front-to-back — change ratios while mounted on robot
Available Cartridges
| Cartridge | Ratio | Notes |
|---|---|---|
| 2:1 | 2:1 | Reverses direction — invert motor in code |
| 3:1 | 3:1 | |
| 4:1 | 4:1 | |
| 5:1 | 5:1 | |
| 9:1 | 9:1 | |
| 1:1 Brake | 1:1 | Sprag clutch — holds position, prevents backdriving |
Combo math: Stack cartridges for compound ratios. Example: 5:1 × 4:1 × 3:1 = 60:1 total reduction.
Brake Cartridge
The 1:1 Brake Cartridge uses a sprag clutch (torque diode) to mechanically lock output when motor is stationary. Automatically engages when output exceeds motor velocity.
Specs:
- Working torque: 16.95 Nm (150 in-lb)
- Static torque (no failure): 1,200 Nm (10,621 in-lb)
- Recommended as first cartridge (closest to motor) for maximum brake life
90 Degree Gearbox
The MAX 90 Degree Gearbox provides right-angle power transmission. Attaches to MAXPlanetary in 90° orientation for compact mechanisms in tight spaces. Through-bore design allows easy mounting.
Connection to Training
For students: The MAXPlanetary teaches gear reduction fundamentals:
- Why reduction? — trade speed for torque. Motor has high RPM, low torque. Gearbox slows it down but multiplies force.
- ** planetary stages** — each cartridge adds one stage of reduction. More stages = more torque, less speed.
- Ratio math — multiply cartridge ratios to get total. 3:1 × 5:1 = 15:1.
- Brake cartridge — mechanical holding, not motor braking. Independent of motor state.
Related training modules:
- motor-basics — understanding motor output before gearbox
- swerving-modules — MK4i doesn’t use MAXPlanetary (direct drive), but mechanisms do
- ion-build-system — integrates with REV ION structure
- 2890-codebase-index — mechanism controllers that use gearbox output
Source Links
- Product: https://www.revrobotics.com/maxplanetary-system-kit/
- Docs: https://docs.revrobotics.com/ion-build/motion/maxplanetary-system
Notes
Chris typically uses MAXPlanetary on mechanisms (intake, shooter, climber) rather than drivetrain. Swerve modules have built-in belt reduction in the MK4i. For any mechanism that needs high torque at low speed — that’s where MAXPlanetary lives.
Key concept for students: gear reduction multiplies torque while dividing speed. A 5:1 gearbox means the output turns 5× slower but the motor can push 5× harder.