Derrick Crane Features Low cost, effective teaching Self-contained Bench mounted Direct readout of jib and tie loads by spring balances Demonstrate principles of equilibrium and polygon of forces Three year warranty Range of Experiments Determination of forces in the crane members Comparison with prediction by the polygon of forces Demonstration of equilibrium of forces Description This apparatus represents the forces in a simple crane and introduces the student to equilibrium of forces and solution by the triangle of forces. The crane is mounted on a base designed to be stood on a level bench. Both the jib and tie include spring balances for measuring the internal forces. A load is hung from the end of the jib. Re-adjustment of the crane geometry back to its original unloaded layout is possible by a knurled adjuster on the jib and adjusting the links of the chain. This equipment is part of a range designed to both demonstrate and experimentally confirm basic engineering principles. Great care has been given to each item so as to provide wide experimental scope without unduly complicating or compromising the design. Each piece of apparatus is self-contained and compact. Setting up time is minimal, and all measurements are made with the simplest possible instrumentation, so that the student involvement is purely with the engineering principles being taught. A complete instruction manual is provided describing the apparatus, its application, experimental procedure and typical test results.