As you likely know, Volvo is Latin for "I roll".  The emblem - a
circle with an arrow, is an alchemical symbol for iron (historically
a symbol of strength).  Together the two mean "rolling strength".

You can see the symbol in the context of iron here:
<http://pearl1.lanl.gov/periodic/elements/26.html>

Beverly

Assar Gabrielsson and Gustaf Larson created the Volvo while working for
a SKF, a Swedish ball-bearing manufacturer, in G?teborg, Sweden.  Volvo
was born on April 14th, 1927, when the first car, which was nicknamed
"Jakob", left the factory in G?teborg.  SKF also provided the factory
premises and the name, AB Volvo, which had been used in a previous
business operation. Volvo is Latin and means "I roll" . The Volvo
circle-and-arrow trademark was created to represent strength, taking its
graphic shape from the traditional alchemist's symbol for iron ore .

In the 1920 circa, before the birth of Volvo Company, car makers built
cars by choosing ready-made parts from catalogs and then assembling into
cars. The results were of poor quality. Volvo had a different
philosophy: they believed quality cars could only be built from
designing components in-house, contracting the designs to be built by
manufacturers and finally assembling the parts by experienced car
builders. Combined with the name, the Volvo graphic identity is "rolling
strength" -- an expression of its approach to building cars.