The rules that use the vocabulary item "hour" are:

<speed_measure-sing>

kilometer an hour

kilometer per hour

klick an hour

klick per hour

mile an hour

mile per hour

<time_interval_unit-sing>

hour

<speed_measure-pl>

kilometers an hour

kilometers per hour

klicks an hour

klicks per hour

miles an hour

miles per hour

<time_interval_unit-hour-sing>

hour

<h_hour>

h hour

l hour