The friction clutch is now used almost exclusively for engaging the
engine with the propelling gearing of the traction drivers, and it will
most likely give you more trouble than any one thing on your engine,
from the fact that to be satisfactory they require a nicety of
adjustment, that is very difficult to attain, a half turn of the
expansion bolt one way or the other may make your clutch work very
nicely, or very unsatisfactory, and you can only learn this by carefully
adjusting of friction shoes, until you learn just how much clearance
they will stand when lever is out, in order to hold sufficient when
lever is thrown in. If your clutch fails to hold, or sticks, it is not
the fault of the clutch, it is not adjusted properly. And you may have
it correct today and tomorrow it will need readjustment, caused by the
wear in the shoes; you will have to learn the clutch by patience and
experience.

But I want to say to you that the friction clutch is a source of abuse
to many a good engineer, because the engineer uses no judgment in its
use.

A certain writer on engineering makes use of the following, and gives me
credit: "Sometimes you may come to an obstacle in the road, over which
your engine refuses to go, you may perhaps get over it in this way,
throw the clutch-lever so as to disconnect the road wheels, let the
engine get up to full speed and then throw the clutch level back so as to
connect the road wheels." Now I don't thank any one for giving me credit
for saying any such thing. That kind of thing is the hight of abuse of
an engine.

I am aware that when the friction clutch first came into use, their
representatives made a great talk on that sort of thing to the green