The evaluations are for resistance to penetration of guards to the point of infringement of the Deflection Limiting Volume (DLV, see SAE J397). The performance requirements of a representative specimen (that is, within the manufacturer's specifications), are based on the performance of proven structures under laboratory evaluation procedures.
The areas protected include the top of the operator station (Top Guard), for protection from falling objects, and the front of the operator station (Front Guard), for protection from objects which approach the front of the cab.
Although falling object guards meeting the following criteria may not give crush protection under all conceivable circumstances in which the machine could be struck from above or the front, it is expected that crush protection will be ensured under at least the loading condition specified in the tests listed in Section 5.
This document establishes a consistent, repeatable test procedure and performance requirements for evaluating guards intended to provide excavator operators with reasonable protection from falling objects such as rocks.