Table of Contents
Advertisement
Crankcase
CRANKCASE DESCRIPTION
The crankcase is the foundation of the engine. It
supports the crankshaft, camshaft, various gears
accessories, cylinders and various brackets. The
crankcase provides a tight enclosure and oil galleries
for lubrication. The crankcase is sufficiently rigid
and strong to prevent misalignment of the
crankshaft, camshaft and bearings. The crankcase is
made of aluminum alloy.
Two aluminum alloy castings are joined along the
vertical center plane to form the complete crankcase.
The individual castings (with studs and inserts) will
be referred to as the "left crankcase" and "right
crankcase" throughout this chapter.
Bosses molded in the crankcase castings are line
bored in the assembled castings to form bearings for
the camshaft and saddles for precision crankshaft
main bearing inserts. Guides are bored through
lateral bosses for hydraulic tappets and on the left
17-2
FIGURE 17-1. CRANKCASE DESCRIPTION
crankcase half for the governor drive gear shaft. A
needle bearing bore is located on the right crankcase
half at the rear main bearing saddle for the starter
adapter needle bearing.
Cylinder mounting pads on the left crankcase are
farther forward than the corresponding pads on the
right crankcase to permit each connecting rod to
work on a separate crankpin. There are seven studs
and two through bolts for attaching cylinder base
flanges. The propeller governor mount pad is located
on the left hand lower front corner of the left case
half. On the right permold crankcase an alternator
pad is located at the front ahead of the #5 cylinder
mount pad.
The crankcase interior is ventilated by a breather that
is part of the oil filler neck inserted into the left
crankcase half in a machined hole between the #2
and #4 cylinders.
Advertisement
Chapters
Table of Contents
