1930 Cadillac Brochure Front Cover - GM Heritage Center

y the General Motors Research Laboratories, to insure that no vibration
may mar the smooth performance of the Cadillac engine.
The backbone of'the Cadillac power plant; the two-plane compensated
crankshaft inherently balanced and built to withstand all manner of
torsional stresses.
rotation of the flywheel and power transmission system. The combined
torsion and bending stresses imposed upon any shafting which
transmits power must be met by considering in their proper relationship
three sets of factors—the unsupported length, the dimensions
of the shaft, and the material used in its construction. The salient
points of the Cadillac engine become especially apparent when the
crankshaft is examined for these three factors.
The Cadillac crankshaft has the shortest overall length of any
engine of equal displacement. The length of the shaft between the
outer ends of the forward and rear main bearings is 23 ff inches, of
which 6\l inches comprise the three main bearings, while the
diameter of the shaft is 2¾ inches. This short overall length and
large diameter eliminate torsional forces and crankshaft whip. The
shaft is forged from a carbon steel of a high tensile and shearing
strength, with the throws lying in two planes and provided with
compensators so that inherent balance is secured. After manufacture
each crankshaft is balanced on a balancing machine, developed
PISTONS
A piston has to withstand the direct impact of the explosion and
transmit this force through the connecting rods down to the crankshaft.
It is essential that the weight of the pistons be reduced to a
minimum and still provide ample strength without distortion when
subjected to the high temperature within the walls of the combustion
chamber.
Nickel cast iron has proved to be the best material for the manufacture
of pistons. Since the cylinder blocks are made of a similar
material, unequal expansion is completely eliminated. The Cadillac
piston design uses this material to the best advantage, giving great
strength and rigidity with a minimum of weight. Because of the
compensated crankshaft,
the effects of piston
weight have been
greatly minimized and
are completely balanced
by the crankshaft. The
pistons are fitted with
four rings, three of which
are mounted above the
wrist pin and one below.
The lowest ring is of the
slotted type in a drilled
ring groove, enabling ex-
[••• ^^59ij
^•"^'.•:i
Testing cars in the cold of the arctic. In this
General Motors cold room, engineers study
llie operation of cars and parts at temperatures
as lotv as 50 degrees below zero
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