Maytronics Dolphin Supreme M5 gear for active brush assembly - 9991043-ASSY

Maytronics Dolphin Supreme M5 gear for active brush assembly

This is the OEM drive gear (part 9991043-ASSY) that sits inside the active brush module on the Dolphin Supreme M5 and a wide range of related models. It transmits rotation from the brush motor to the active brush roller, keeping the scrubbing action consistent and properly timed. When this gear fails, the brush roller stops spinning independently of the robot’s travel — and scrubbing performance drops immediately.

What this gear does in the Dolphin

The active brush system is motor-driven rather than passively wheel-turned, meaning the brush roller spins under its own power to agitate pool surfaces. This gear is the mechanical link between the motor output shaft and the brush roller shaft. A worn or cracked tooth on this gear causes the brush to stall intermittently or stop entirely, while the drive tracks continue running normally — a classic symptom pattern that points directly to this component.

Which Dolphin models it fits

This gear is confirmed across a broad Dolphin platform that shares the same active brush module architecture. Verified fits include the Supreme M4 and M5, Wave 65 and Wave 90, M3 (E55), Bio, C3, C4, M400, M500, Odyssey, Nautilus CC Supreme, and Wave 60 and Wave 80. Always cross-reference your robot’s parts diagram against part number 9991043-ASSY before ordering.

Signs it needs replacing

The most reliable indicator is a brush roller that spins freely by hand but does not rotate during a cleaning cycle — the gear teeth have stripped and the drive torque no longer transfers. You may also hear a faint clicking or skipping sound from the brush housing during operation, which indicates a tooth is chipping before full failure. Inspect the gear visually by removing the brush assembly cover; cracking or missing teeth confirm replacement is needed.

How to install it

Remove the brush assembly cover using a Phillips screwdriver, lift out the brush roller, and locate the gear on the motor output shaft inside the housing. Pull the old gear clear of the shaft, press the replacement on until fully seated, then reassemble in reverse order. The whole job takes roughly 10–15 minutes and requires no special tools beyond a screwdriver.