Patent ID: 7438075

Claim:
A carwash for washing a vehicle in a wash bay, wherein the vehicle has at least four surfaces including a left side, a right side, a front end, and a back end, the carwash comprising: an overhead supporting structure; a trolley supported by the overhead supporting structure and being movable within the wash bay; a spray arch extending downward from the trolley and being movable therewith, wherein the spray arch can rotate more than 180 degrees about an axis to spray the four surfaces; a first emitter for projecting a first beam that may be interrupted by the vehicle, wherein the first emitter projects the first beam in a direction that lies at an acute angle with the axis about which the spray arch rotates; a sensor being substantially fixed relative to the first emitter and being operable to change from a state of discontinuity to a state of continuity upon detecting the first beam, wherein the sensor provides a position feedback signal that indicates in which state the sensor is operating and is used to determine positions of both the right side and the left side, both the first emitter and the sensor are directly attached to the spray arch, whereby both the sensor and the first emitter move with the spray arch, the sensor and the first emitter are vertically and horizontally spaced apart from each other; and a controller connected to receive the position feedback position signal and provide a command signal in response thereto, wherein the command signal causes the spray arch to sequentially traverses the front end, the left side, the back end, and the right side, but not necessarily in that order.