Abstract: A crane or the like (e.g. an access platform or excavator), having a boom wherein the boom is lifted or lowered by one or more hydraulic rams or the like, the or each ram acting on a cradle on which the boom rests and in which it is free to move, the cradle being linked to the platform or the base of the crane or the like, at a point between the foot of the ram(s) and the foot of the boom or at the foot of the boom. This arrangement has the advantage that the boom stresses during lifting are evened out, and expensive accurate machinery of the boom pivot holes are avoided.

Abstract: A dynamometer, used to measure the tension on, speed of, and direction of movement of a hoist rope on a crane, includes a frame comprising three spaced apart blocks coupled to one another by pairs of thin flexible resilient portions. Two pulleys are mounted to the outermost blocks while an offset pulley, coupled to a tension monitoring load cell, is mounted to the central block and presses against the rope. One pulley has three permanent magnets imbedded about its periphery, two being axially spaced across from one another and the third being spaced radially 180.degree. from the others. Sensors mounted to the frame are positioned to sense the passing of the magnets to provide rope speed and direction of travel information in digital form. Tension information from the load cell and speed and direction information from the sensors are supplied to a microprocessor for processing.

Abstract: A boom for a crane or the like which comprises four longitudinal stiffening members interconnected with four substantially flat longitudinal plates in such a way that the boom has a substantially diamond shaped cross-section. Such a construction has considerable advantages as compared with normal rectangular section booms, e.g., reduction of stress at the corners, elimination of internal fillets, reduction of distortion and easier and better construction of the boom.

Abstract: Described herein are cranes and particularly those which are stability balanced, normally mounted on a truck or similar vehicle and provided with a boom of telescoping sections. The crane according to the invention has a boom provided with an upper lattice extension and a fly jib, attached (preferably pivotally), to the boom adjacent the top thereof or to the lattice extension at a point on the lower half of the extension. As this arrangement provides a reasonable length of boom, or lattice extension thereof, above the connection point of the fly jib, a substantial moment arm is provided enabling a relatively long and heavy fly jib to be employed giving greater stability to the top portions of the crane. Also the arrangement enables increased lift capability, at comparable radii, as compared with a standard crane, or similar lift capabilities at an increased working radius.

Abstract: A crane having a novel data processing system which uses a microprocessor (22), to calculate mathematically the actual jib radius (R.sub.1) from inputs corresponding to jib head angle elevation, jib base elevation and jib length from head (9) to base (8). The system provides actual data which can be fed to a display (10) and which can actuate alarms (24), (26) on reading a safe load stored in a load table in a microcomputer of which the microprocessor forms a part. The actual data can also control motion cut offs, automatic luffing and automatic stowage. A novel dynamometer (30) is also included which can measure crane hoist loads, speed and direction.