1. Field of the Invention
The present invention relates in general to a safety securing system for an operational lever. More particularly, the present invention relates to an operational lever including a pair of switches providing redundant safety security.
2. Description of the Related Art
Joysticks are well known and widely employed for operator input of motor vehicles. Joystick control devices are known for heavy work vehicles such as front-end loaders, as described in U.S. Pat. No. 5,701,793, and for fork-lift vehicles, as described in U.S. Pat. No. 6,226,582. Joysticks are frequently used on vehicles having significant hydraulic operational components, such as hydraulically powered drive means, steering means, and work implements e.g., buckets in the case of front-end loaders, or booms in the case of cranes and back-hoes.
The operating position for joystick controlled vehicles often provides for an operator in a sitting position. Armrests are often provided for the operator. Joysticks conveniently located in the armrest may be seen as reducing operator fatigue. Reduced fatigue may, in turn, advance worker safety for both the vehicle operator, and others working in the vicinity of the vehicle.
Vehicles often include means for adjusting the armrest position. Armrest adjustment permits different sized individual operators to place the armrest in a comfortable position. Further, an individual operator may periodically vary the position of the armrest during the course of the operator's work day. Varying the position of the armrest is particularly advantageous in the case of vehicles in use for agricultural and civil works construction, as the work days in these industries may be extended to accomplish the necessary tasks while weather cooperates.
Arm rests may rotate in a vertical plane about an axis located, for example, in the vicinity of the sitting operator's elbow, as an example of a point of adjustment. Further adjustment may be provided by rotation of the arm rest in a substantially horizontal plane.
Entry into and exit from the operator area by an operator often requires an operator to move the armrest from an operating position into an exit position. In many vehicles, the armrest is rotated in a vertical plane in order to move the armrest into a substantially vertical orientation, thereby providing the operator easy access to enter and exit the operator area. Unless the operator is in a position to control the vehicle, safety features may be employed in order to interrupt electrical signals sent from the joystick mounted upon the armrest to the vehicle controller.
Known interlock devices include switches integrated with operator seats whereby the weight of an operator in the operating position is required to initiate the starting sequence, or to send electrical signals to activate the vehicle. Armrest joystick signal interruption referred to as “Comfort Drive Control” for use in numerous wheel loaders is provided by the manufacturer Volvo and disclosed in U.S. Design Pat. No. 377,476. This armrest includes a single limit switch, and armrest adjustment is limited to rotation in the vertical plane only.