Verb
topple over (third-person singular simple present topples over, present participle toppling over, simple past and past participle toppled over)
(idiomatic) To fall over (to fall from an upright or standing position to a horizontal or prone position).
A gentle nudge will knock it off its axis of rotation for a second but it will not topple over because spin adds gyroscopic stability. Source: Internet
If the subject holding the wheel removes one hand from the end of the axle, the wheel will not topple over, but will remain upright, supported at just the other end of its axle. Source: Internet
If the wheel was not spinning, it would topple over and fall when one hand is removed. Source: Internet
A FORKLIFT truck driver made a fatal decision when his vehicle began to topple over. Source: Internet
It’s also designed to be stable, so kids doing cartwheels in the chair won’t topple over into a heap. Source: Internet
The ostensible action of the wheel beginning to topple over is equivalent to applying a force to it at 12 o'clock in the direction of the unsupported side (or a force at 6 o’clock toward the supported side). Source: Internet