Ezekiel 10:9-11

9Then I looked and saw four wheels beside the cherubim, one wheel beside each cherub. And the wheels gleamed like a beryl stone. 10As for their appearance, all four had the same form, like a wheel within a wheel. 11When they moved, they would go in any of the four directions, without turning as they moved. For wherever the head faced, the cherubim would go in that direction, without turning as they moved.