Abstract: The reliability of electronic navigational equipment, such as missile guice sets, frequently requires a precisely-aligned support or mounting which must be rigidly maintained during the missile operation or flight. To maintain the alignment, the housing for the electronics is rigidly supported by a link mechanism pivotally coupled at one end to the missile airframe and, at the other, to the electronic housing through a crosshead assembly which includes a crosshead block slidably mounted in dove-tailed tracks of a crosshead guide carried by the housing. A spring-urged plunger of the crosshead assembly has its ends engaged in steep-walled detents to normally, during flight, lock the block in a fixed position. Extreme, non-operational, acceleration forces such as otherwise would damage the electronics, overcome the spring force on the plunger permitting a slidable breakaway displacement. Resilient shock absorbers then protectively cushion the force.