Figure 3-26.Cam-ground piston action.
There are two types of piston skirts in most
enginesFULL TRUNK and PARTIAL SKIRTED
(SLIPPER) (fig. 3-28). The full trunk type of skirt has
a full cylindrical shape with hearing surfaces parallel to
those of the cylinder. This gives it more strength and
better control of the oil film. The partial skirt or slipper
skirt has considerable relief on the sides of the skirt.
Removal of the skirt in these areas serves the following
Lightens the piston, which, in turn, increases the
speed range of the engine.
Reduces the contact area with the cylinder wall,
which reduces friction.
Allows the piston to be brought down closer to
the crankshaft without interference with its
Figure 3-27.Cam-ground piston.