The phrase "a main engine of" is correct and usable in written English.
It can be used to describe something that plays a significant role in driving or facilitating a particular process or outcome.
Example: "Innovation is a main engine of economic growth in today's society."
Alternatives: "a key driver of" or "a primary force behind".
The tensions have prompted four Arab countries — Qatar, Bahrain, Kuwait and the United Arab Emirates — to warn their citizens not to travel to Lebanon, which could deal a large blow to the pending summer travel season, a main engine of Lebanon's economy.
Nervousness about the state of the Chinese economy — a main engine of global growth and an important market for companies like General Electric, Volkswagen and Louis Vuitton — has weighed heavily on markets worldwide for much of the past year, as it became clear that the pace of growth was slowing considerably.
The braking manoeuvre calls for a main engine burn of more than two hours, but in that time the spacecraft will pass behind the red planet and lose all communications with Earth.
China is the fastest-growing large economy and, so far, a main engine pulling the world out of recession.
With easier access to capital, private companies have a chance at becoming the main engine of China's economy for the first time since a brief period earlier this century and otherwise since the Song Dynasty nearly 1,000 years ago.
Signs of a slowdown in China, the main engine of global growth in recent years, have knocked investor confidence around the world and sparked sharp moves in other stock markets as well as for commodity prices.
Egypt is undergoing a severe liquidity crisis caused by the loss of hard currency from few sources: tourism was a key source of foreign exchange and the main engine of growth.
In the bubble years the main engine of Ireland's economy was a housing boom that eventually ran out of control.
Adjusted for inflation, the average home is worth less than it was a year ago.The housing boom has been the main engine of America's economic growth in recent years.
Industrial production fell in November, underscoring a slowdown in the corporate sector, which had been the main engine of Japan's recovery.
The president-elect also advocates for the open market as the main engine of innovation, through what he calls a "positive technological shock".
