TM 1-1500-204-23-1
2
Power section. The power or main
section may be of one-piece or two-piece construction
and usually consists of one, two, or possibly three pieces
of high-strength heat-treated aluminum-alloy or steel
forging, bolted together if there is more than one piece.
The cam-operating mechanism is usually housed and
supported by the power section. At the center of each
Figure 7-4. Opposed-Type Crankcase
main crankcase web section are crankshaft bearing
supports. Cylinder mounting pads are located radially
around the outside circumference of the power section.
The cylinders are fastened to the pads by means of studs
and nuts or cap screws. Oil seals are located between the
nose section and the power section. Similar seals are
installed between the power section and the supercharger
section.
3
Supercharger
section
The
supercharger section is normally located immediately
behind the main power section and may be of either one-
piece or two-piece construction. Its principal function is to
house the blower or supercharger impeller and diffuser
vanes There are openings on the outside circumference
of the housing for attaching the individual induction pipes,
a small opening for the attachment of the manifold
pressure line, and internal-passages which lead to the
supercharger drain valve.
4
Accessory section The accessory
section provides mounting pads for the accessory units
such as the fuel pumps, vacuum pumps, lubricating-oil
pumps, tachometer generators, generators, magnetos,
starters, two-speed supercharger control valves,
Figure 7-5. Radial-Type Crankcase
7-3
