Brass ring

It takes some dexterity to grab a ring from the dispenser as the carousel rotates.

Typically, getting the brass ring gets the rider some sort of prize when presented to the operator.

[2] As the carousel began to turn, rings were fed to one end of a wooden arm that was suspended above the riders.

Riders hoped that the timing of the carousel rotation (and the rise-and-fall motion of their seat, when movable seats were included in the outer circle of the carousel) would place them within reach of the dispenser when a ring (and preferably a brass ring) was available.

It is not clear when the phrase came into wide use but has been found in dictionaries as far back as the late 19th century.

Catching the brass ring.
Brass Ring dispenser and target on Santa Cruz Beach Boardwalk 's Looff Carousel in Santa Cruz, California The dispenser is visible as an arm crossing to the upper left, where a rider is grabbing the ring
A rider of the Flying Horses Carousel reaches for the brass ring.
Brass ring dispenser on arm end, from the carousel in Glen Echo Park (Maryland) [ 1 ]