A fully developed system from Perini & Scott which has operated for over 15 years in container and freight handling terminals in a number of countries. It enables a Rubber-tyred Gantry Crane to follow a buried wire carrying a discrete frequency current with high accuracy regardless of changing ambient conditions (rain, surface flooding and snow). It serves a safety purpose by releasing the crane driver from the onerous task of steering and increases the productivity of the crane. It has been fitted to a wide variety of cranes both electric (AC & DC) and hydraulic. It can be supplied as an OEM item or retrofitted as a bolt-on box.               Our latest development simplifies guidance in that we no longer require any sensor detecting the position of the hydraulic ram or any other part of the mechanical linkage which actuates the wheel-yoke rotation. The guidance system is in fact configured without any need to identify the particular geometry of the cylinder-ram-yoke linkage used and is therefore ideal for retrofit application of a standardised package on cranes from various builders and to a variety of cranes at a site. No new elements are required in the guidance system; the required functionality is obtained by sensing the loop with an extra detector mounted inboard which like all the other AUTOTRACK elements are well-proven in rubber-tyred container-handling crane operations for over 20 years.       An addition to Rubber-tyred Gantry Cranes fitted with AUTOTRACK which with the addition of a second buried wire loop or a modification to the geometry of the guidance loop for a new installation, will prevent the vehicle passing over a nominated area while laden or passing a nominated point.                     This stand-alone system is primarily designed for diesel-hydraulic rubber-tyred gantry cranes with fixed wheel yokes via speed differential or for cranes with an Ackermann steering characteristic via wheel-yoke rotation.                         Instrumentation to determine in real time the depth of the sludge/mud in either a clarifier where the output is clear water or a thickener where the output is concentrate. This depth measurement is critical to the control of flocculant dosage. The systems can have degrees of complexity ranging upwards from a float with adjustable buoyancy. All systems have analogue 4-20mA outputs as standard with other outputs by arrangement.                         At the request of some clients Perini & Scott have developed specialised proprietary solutions in conjunction with the client's chemical and instrumentation engineering groups. This service is available to corporations and organisations which have unique processing requirements.