linchpin

When the linchpin comes out on his side, there'll be a jerk, I tell you!

I will try to be brave, ma'am; but I really did try to put the linchpin back.

If an axle had broken or a linchpin loosened the race would have been lost.

A linchpin had fallen out, and permitted one of the wheels to slide off.

Linchpin, linsh′pin, n. a pin used to keep the wheel of a carriage on the axle-tree.

That I driv yer honour the last three miles without a linchpin!

This thin wedge end of the drawbolt is placed under the end of the linchpin.

Upon inspection, the losses of the day were found to be one linchpin and one pair of pantaloons.

His famous monologue with his imaginary friend "Linchpin" invariably brought the house down.

If Boston is the hub of the universe, Concord might be considered as the linchpin which holds it on.