MIL-S-901
Military Specification MIL-S-901D is for high-impact mechanical shock which applies to equipment mounted on ships. Its publication date was Mar 17, 1989. Two levels apply: Grade A items are items which are essential to the safety and continued combat capability of the ship; Grade B items are items whose operation is not essential to the safety and combat capability of the ship but which could become a hazard to personnel, to Grade A items, or to the ship as a whole as a result of exposure to shock. "Grade C", signifying that no shock qualification is  required, is also sometimes referenced in acquisition documents even though the term has no official standing in the specification document. Qualification testing is performed on a specified machine or on a barge floating in a pond where an explosive charge is detonated at various distances and depths in the pond to impart shock to the barges. The MIL-S-901D specification covers shock testing requirements for ship board machinery, equipment, systems, and structures, excluding submarine pressure hull penetrations. The purpose of these requirements is to verify the ability of shipboard installations to withstand shock loadings which may be incurred during wartime  service due to the effects of nuclear or conventional weapons. Test classifications. Tests shall be classified in accordance with one of the following test categories, as specified. Items to be tested shall be classified in accordance with one of the following grades, as specified: Items to be tested shall be classified in accordance with one of the following classes, as specified: Tests shall be classified in accordance with one of the following types, as specified: Barge Test. The Barge Test or Heavyweight Test requires the item under test to be mounted on a floating barge. For the Standard Floating Platform , 60 pounds of HBX-1 explosive is placed 24 feet under water at various distances from the barge and detonated. There are four 'shots'. The first is placed on the Fore-and-Aft axis, 40 feet from the barge. Shots 2, 3, and 4 are placed athwart ship at distances of 30, 25 and 20 feet. The distance refers to the near side of the floating platform. For the Large Floating Platform, 300 pounds of HBX-1 is placed 20 feet under water and the distances are 110, 80, 65, and 50 feet from the barge with the first shot Fore-and -aft and the other three shots athwart ship. A hammer test can be used to Pre-qualify an item and to identify deficiencies but, ultimately, the items to be certified compliant with MIL-S-901D will be tested on a barge. Applicability to products. Suppliers can and some do take significant latitude with how they test their products, as well as how they report the test results. As a result, claims of "compliance with MIL-S-901" can be misleading. Users who require rugged products should verify the test methods (i) against which compliance is claimed; ii) to which parameter limits were  actually tested; and (iii) whether the testing was done internally or externally by an independent testing facility. Products: electric motors. Military standard MIL-DTL-17060G(SH), confirms two types of electric motors, Service C and Service A. High-impact shock test for electric motors is defined into weight categories. Tests for lightweight motors shall be nine blows delivered while the motor is operating under no-load at nominal speed. An additional nine blows shall be delivered with the motor stationary. Tests specified in MIL-S-901 for medium weight motors shall be conducted with the motor running under no-load at nominal speed  or with the motor stationary. Motors may be submitted for each series of three blows  Motors weighing 250 pounds or less shall be tested on the lightweight shock testing machine. Motors weighing in excess of 250 pounds and up to 6,000 pounds shall be tested on a medium weight shock testing machine. Motors weighing over 6,000 pounds shall be tested on a floating shock test platform or barge test.