This invention relates to an improved actuator, and to an operating key for use in an actuator. 
Actuators comprising a switch and an operating key are known.  Such switches find application in equipment such as machine guards, machine tool doors, and the like, where opening of the guard or door causes the key to be removed from the switch.  This seeks to ensure that the equipment is isolated from an electrical power source such that the equipment cannot be operated while the guard or door is opened.  Closing of the guard or door causes the key to be inserted into the switch thereby allowing power to be supplied to the equipment. 
Normally, the switch is mounted to a body of the equipment, while the key is mounted to a moveable part of the equipment, such as a guard or door.  However, the switch and the key can be swapped round if preferred. 
At present, manufacturers of actuators require to provide a range of operating keys.  For example, it may be required to provide a straight key for sliding guards capable of being mounted on a surface of the equipment parallel to an actuation direction.  It may further be required to provide a key capable of being mounted on a surface of the equipment perpendicular to the actuation direction. 
It may also be desirous to provide keys particularly for use on hinged doors or guards.  For example, it is known to provide an adjustable key for horizontal radius pivoting guards as hereinafter described.  It is also known to provide an adjustable key for vertical radius pivoting guards. 
Known adjustable actuators are “spring loaded” by means of longitudinal banding of a coiled spring provided with the operating key. 
Known actuators and operating keys provide a number of problems.  For example, a manufacturer requires to make a number of keys for use in different scenarios, as mentioned above.  Further a manufacturer of equipment requires to stock a number of different actuator and key types. 
A further problem exists with known adjustable keys in that they are often limited to an unacceptably high operating radius, eg.  of around 160 to 220 mm. 
It is an object of at least one aspect of the present invention to obviate or at least mitigate one or more of the aforementioned problems in the prior art. 
It is a further object of at least one embodiment of the present invention to provide a “universal” operating key, ie.  one which may be used in various applications, such as, both horizontally and vertically pivoting guards. 
It is a further object of at least one embodiment of the present invention to provide an operating key which allows an actuator to be used at a smaller operating radius than presently possible. 
It is a yet further object of at least one embodiment of the present invention to provide an improved operating key which can be used with known and presently available switches.