1.
both wheels (of a vehicle)
The two wheels of a bicycle, cart, or similar two-wheeled object. The literal sense, less common in modern speech than the figurative one.
自転車の両輪を点検した。
I inspected both wheels of the bicycle.
2.
two essential elements (working in tandem)
Figurative: two things that are both indispensable and only work together — like the two wheels of a cart, where one alone cannot move. A standard metaphor in business, policy, and education writing.
勉強と部活は学校生活の両輪だ。
Study and club activities are the two wheels of school life.
営業と開発は会社の両輪と言える。
Sales and development are the two wheels of the company, so to speak.
経済成長と環境保護は現代社会の両輪として機能しなければならない。
Economic growth and environmental protection must function as the two wheels of modern society.
Compound of 両 (both) + 輪 (wheel). The figurative sense (sense 2) is far more common today and is a fixed metaphor: "like a cart's two wheels, both are necessary and neither can replace the other."
COMMON COLLOCATIONS (figurative):
- 〜の両輪: the two pillars of 〜
- 両輪として機能する: to function as the two essential parts
- 両輪を担う: to take on one of the two roles
- 車の両輪: like the two wheels of a cart (a set idiom)
USAGE PATTERN:
"A と B は X の両輪" (A and B are the two wheels of X) is the canonical frame, asserting that both are indispensable.
SIMILAR WORDS:
- 両立: balancing two things — about juggling them, not their being inseparable
- 表裏一体: two sides of the same coin — emphasizes inseparability of opposites, not partnership