Fail-safe switch

A switch for interrupting an electrical connection between two terminal contacts, comprising:

• a plunger, which when actuated causes the electrical connection to be made, and when released causes the electrical connection to be interrupted;
• a conductive element, the positions of the terminal contacts and the conductive element with respect to each other being dependent on the position of the plunger, the conductive element having first and second contact areas, each of the contact areas being selectively and operationally connected and disconnected with one of the terminal contacts, respectively;
• a cycle control surface disposed in relation to the plunger, the cycle control surface comprising at least one trap;
• a contacting member which operationally contacts at least part of the cycle control surface as the plunger is actuated and released;
• wherein at least one of the cycle control surface and the contacting member moves with respect to the other of the cycle control surface and the contacting member when the plunger is released and the first and second contact areas and the terminal contacts are not prevented from being operationally disconnected from each other;
• and
• wherein when the plunger is released and one of the contact areas and one of the terminal contacts are prevented from being operationally disconnected from each other, the contacting member is prevented from leaving the at least one trap, thereby restraining movement of the contacting member and the cycle control surface with respect to each other, and thereby preventing the electrical connection between the two terminal contacts.

A vehicle, comprising:

• a source of electrical power;
• a drive train controlled by the source of electrical power and operable to move the vehicle;
• a safety switch operationally connecting the source of electrical power and the drive train, the switch actuatable between an "on" state in which the source of electrical power transmits motive power to the drive train and an "off" state in which electrical power is not transmitted to the drive train by the source of electrical power, the safety switch including
• first and second terminal contacts;
• a contactor structure including first and second contactor contacts electrically connected to each other, the switch having an "on" state in which the first and second terminal contacts are contacted with the first and second contactor contacts, respectively, to thereby electrically connect the terminal contacts therebetween, the switch further having an "off" state in which the terminal contacts are not electrically connected to each other by the contactor structure whereby current cannot flow between the terminal contacts;
• and
• a cycle control mechanism having a normal-state in which the switch is free to cycle between the "on" and "off" states, the cycle control mechanism further having a welded-state in which one of the terminal contacts is welded to one of the contactor contacts and the other of the contactor contacts is separated from the other of the terminal contacts, wherein in the welded state the cycle control mechanism prevents the switch from moving from the "off" state to the "on" state.