LO 7-2 Classify pistons according to their application, design, construction features, and material

1.5. Slipper Skirt Pistons

Slipper Skirt Pistons

In the design of a slipper skirt piston, a portion of the skirt is removed on both non-thrust sides of the piston. These sides of the piston are not heavily loaded by compression of combustion forces. When combined with the angle of the connecting rod, this forces the piston against the cylinder wall Figure 10. When sections of the piston skirt are removed, more clearance is available for the turning radius of the crankshaft counterweight when the piston approaches bottom dead center (BDC) Figure 11. Slipper skirt pistons enable the use of shorter connecting rods, which permits the manufacture of vertically smaller, lighter, more compact engines. This is important when the vertical profile of the engine must be kept short in order to fit into a smaller vehicle, such as in a pickup, van, or automobile. More compact engines also translate into lighter block designs for better vehicle dynamics. Slipper skirt pistons are often used in smaller V-block diesels where compact engine design is vital.

FIGURE 07-10: Major and minor thrust forces are created by a combination of an angle between the connecting rod and the piston plus the cylinder pressures during the compression (minor thrust) and power (major thrust) strokes.

FIGURE 07-11: This piston uses a slipper skirt piston design.