Arrangement for retaining an actuating member in an extreme position

An arrangement for retaining an actuating member in an extreme position thereof and for releasing the actuating member to perform a working stroke, comprising:

• a housing;
• a plurality of undeformable supports mounted within said housing in spaced relationship;
• an undeformable connecting element permanently cooperating with said actuating member, said connecting element being received between said supports;
• at least one coil of wire stressively wound about said supports to product elastic deformation of tension of the wire for urging said supports to engageably retain said connecting element with an effort sufficient to hold said actuating member in an extreme position thereof, said coil of wire being selectively connectable to a power supply source whereby when said wire is connected to the power supply the temperature of the wire increases resulting in reduced elastic deformation in the wire and said effort is reduced in magnitude so that said connecting element is released to be displaced relative to said supports and said actuating member is permitted to move through its working stroke.