This may be the most difficult chapter of the text, in part because the author likes long sentences. It is also quite abstract. The president has two kinds of relationships in the executive branch that must be separated. First, he must deal with his appointed advisors and second he has to deal with the more permanent professional bureaucracy. Both relationships are difficult and getting them working together is even more difficult.
All presidents have problems here.
He then uses these types to look briefly at Reagan and Bush, and then more closely at Clinton. Clinton has had problems in being the type he is probably best suited to be. He has not used either of the gearboxes very well. Clinton's relationship with congress in his first two years is the focus of this chapter. He did do some things well, like setting up a good liaison staff and working with Democratic leadership.