• Comparison of measured forces with a triangle of forces and theoretical values.
  • Comprehension of the action of the crane cable forces on the jib and the effect of the jib inclination.


  • Determination of forces in the crane members.
  • Confirmation by theory and polygon of forces.
  • The wall mounted crane consists of a compression jib, and a tension tie which is adjustable, and both incorporate a linear, direct reading spring balance to measure the forces in them.
  • A load hanger applies loads through the junction of the two.
  • Folds flat when not in use. Jib and ties re-adjustable to the original length.
  • Set of weights.
  • Comprehensive technical manual.
  • Set of slotted weights included

This unit is designed to study forces in jib crane elements. Jib crane has two elements which are attached to a vertical rod. The lower element is called jib and the upper element is termed as tie. Load is applied at the junction of jib and tie to produce tension and compression in tie and jib respectively. The unit consists of a metallic rod which provides the support locations for jib and tie. Load is applied via a hanger on the junction of jib and tie. To measure the deformation in jib and tie, spring balance is attached to ‘tie’ and ‘force gauge’ is attached to jib.

Although wall jib cranes are obsolete, the self evident confluence of the four forces at the end of the jib illustrates the application of a triangle of forces so clearly to a real situation that this is an invaluable lesson.

This wall mounted self-contained jib crane has spring balances built into its two members. After loading the member lengths can be adjusted to their no-load lengths. The jib out-hangs and the crane cable inclination can be readily changed FF-1110 Jib Crane.