The castle of al-Shawbak is located in Jordan. New research in the area, under the University of Florence’s archaeological mission “‘Medieval’ Petra: Archaeology of the Crusader-Ayyubid Settlement in Transjordan” shows that the Crusader installation was preceded by a Late Roman-Byzantine fortified settlement. After its fall into Muslim hands in 1189 the regional political importance of the castle was strengthened under the Ayyubids, who added monumental and productive buildings. In the 1990s the Department of Antiquities of Jordan undertook a clearance campaign in the area of the major monumental buildings in the northeastern part of the castle. During this work a quantity of stone elements was unearthed. Among epigraphic fragments, decorative architectural elements, millstones, and many spherical stone projectiles of various diameters, a particular element carved into a limestone block was recognized. Around 2000-2002 the Ministry of Energy and Mineral Resources completed a new clearance campaign for consolidation works in the southern part of the castle and a second element of the same kind came to light. If we consider the two specimens from al-Shawbak, although the archaeological context has been lost and a preliminary search for published archaeological comparisons did not succeed, their apparent similarity with drawings of counterweight artillery guided our research attempting to specify the type of engine to which the artifacts belonged, and to propose a reconstruction of the coupling system and of their chronology, starting from a concise review of Arab military treatises and related iconography. The hurling engines to which the elements most probably belonged are indicated by the Arabic terms ʿarrādah and manjanīq.