Lever mechanisms of all shapes and sizes are very common parts of machines, particularly in hand operated devices. The bell crank lever offers the typical mechanical advantage of a lever, and in addition it turns the line of action of the effort through 90°. In most cases the cranked lever would be a casting with a bushed pivot at the corner. The experimental model has been built up from plastic to simulate the real thing.
This traditional item enables the reaction force of a 90° bell crank to be measured by a spring balance when a load is applied at any of five leverage ratios.
A sturdy aluminium base frame supports a vertical pillar onto which pivots the bell crank lever. The bell crank lever contains five loadings rings into which the load hanger can be fitted to vary the mechanical advantage of the system.
A spring balance is supported horizontally at the base of the bell crank lever, and has an adjustable mechanism to enable the datum position to be returned.
A set of calibrated weights is supplied with the experiment along with a comprehensive instruction manual for student and lecturer.
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.