# reciprocal to circular motion

#### VicNicSor

##### Banned
crank
a part of an axle or shaft bent out at right angles, for converting reciprocal to circular motion and vice versa
Oxford dictionary

Does the phrase in bold here act as an adjective meaning "reciprocal motion is converted to circular motion"? That is -- "reciprocal-to-circular".
Thank you.

• #### JulianStuart

##### Senior Member
Yes - for example, in an internal combustion engine, the reciprocal motion is the "up and down" of the piston and it is converted to circular motion by this connection.

Thank you.

#### Wordsmyth

##### Senior Member
Does the phrase in bold here act as an adjective meaning "reciprocal motion is converted to circular motion"? That is -- "reciprocal-to-circular".
Thank you.
That is indeed the meaning, Vik, but I don't see "reciprocal to circular" as an adjectival phrase. That would make 'reciprocal-to-circular motion' a kind of motion that the crank converts to ...what?!

In fact there's an ellipsis in the original sentence (a very common construction): "... for converting reciprocal (motion) to circular motion and vice versa".

So "reciprocal" is an adjective qualifying the implicit noun "motion", and "circular" is an adjective qualifying the noun "motion". "To" is a preposition introducing the noun phrase "circular motion" (or, if you prefer, a preposition heading the prepositional phrase "to circular motion").

By the way, that definition of "crank" is somewhat inaccurate. If you just bend part of a shaft out at right angles, you don't get a crank. You also have to put in a second right-angled bend in the opposite direction.

Ws

#### VicNicSor

##### Banned
Thank you
By the way, that definition of "crank" is somewhat inaccurate. If you just bend part of a shaft out at right angles, you don't get a crank. You also have to put in a second right-angled bend in the opposite direction.
I thought that "at right angles" meant just that (two bends)...

#### srk

##### Senior Member
"At right angles" essentially means just one. The legs of a right triangle are at right angles to one another.

#### VicNicSor

##### Banned
I see, thank you.

#### JulianStuart

##### Senior Member
One could use the "reciprocal-to-circular" adjective to describe the conversion

#### Wordsmyth

##### Senior Member
One could use the "reciprocal-to-circular" adjective to describe the conversion
One could, as in "..., for applying a reciprocal-to-circular conversion to a motion, or vice versa." (But I wouldn't recommend it, Vik.)

Ws

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