Every hour is steered by another hour. To steer means "to indicate the direction", and is used in the tone clock to indicate the relation between the triads, in a way that can be compared to how steps in changes are being referred to in jazz. 
For example, the changes II-V-I , very common in jazz, are being steered by fourths, meaning: every next step is a fourth. In the tone clock we find the fourths in the ninth hour, so the cadenza II-V-I is being steered by the ninth hour  In this way all the hours have their own steering. 
The first hour, for instance, is steered by minor thirds. The diminished tetrad, consisting of four minor thirds can be found on the tenth hour of the tone clock. This concludes that the first hour is steered by the tenth hour. The second hour, for instance, is steered by the eighth hour, and the fourth hour is steered by the sixth hour. 

In the example on the left half of this page all the hours are displayed with their steerings. Some of the hours are only steered by one other hour, and others can be steered by more than one. There are of course much more possibilities, but they all result in the same combination of harmonies. For instance in his book, Peter Schat also mentions the steering of the eighth hour by the the fourth hour (4-1-4, for instance G-B-C-E), but this is a variation on the steering by the eleventh hour (4-3-4, in vb. 1: C-E-G-B). Notice that the notes are the same, they are only placed in a different sequence. 

The principal of steering described in this chapter, concerns the basic steering of the complementary triads of the tone clock. Steering can also be used in a much broader sense, for instance to a steer a random chord through the twelve tone field, or even to analyze classical compositions, as far back as the renaissance. 
For example: In an article in Entre'Act (Dutch magazine), Andre Douw analyses a part of the composition Voiles (Preludes 1/2, 1910) by Debussy. Intervals (secundes, minor thirds, major thirds and tritones) are being steered by the whole tone scale. The whole tone sequence is found on the sixth hour of the tone clock, so these intervals are being steered by the sixth hour. 

Other possible ways of steering are described in some of the following chapters of this article.