If an engine spins too quickly, valve springs cannot act quickly enough to close the valves.
The engines are not actually spinning in reverse, as the term may lead you to believe.
In a car, you need a clutch because the engine spins all the time, but the car's wheels do not.
At 70mph the engine is spinning at just under 2,000rpm in top, with sufficient in-gear acceleration to deal with most situations.
There was a window that showed a black sky punctuated with stars, and in the room itself, mounted on rigid metal bars, eight engines were spinning.
The engines were spinning on rigid shafts, and it should be the shafts that spun.
- A jumpship slid by fifty meters away, its engines spinning flames like a furnace.
He tried again; once more the engine spun without firing.
He started the engine and the propeller spun.
Even this relatively small engine will spin the rear tires easily if four-wheel drive is not engaged.