Ballista

Three sizes of these giant crossbows are used by dwarves. They fire large bolts in flat trajectories. Each ballista requires a crew to move, load, and fire. They are slow to load; the rate of fire displays how often they may be fired.

When used in dwarf strongholds, ballistas have pedal and gear systems similar to a Grinder. This, coupled with a winch system, allows them to be moved back and forth and traversed from side to side. A ballista is pedaled forward to fire its bolt, then winched back, out of sight, to be reloaded.

[Complete Book of Dwarves]