Short answer
A messenger seat (commonly called a saddle or hook-head saddle) is fitted at the end of the cantilever or on a rigid cross-beam and cradles and positions the messenger wire: it transfers the vertical load of the messenger wire into the supporting structure, allows the wire to slide longitudinally as temperature changes (especially important in fully compensated suspension) and at the same time prevents the messenger wire from lifting out of the seat.
Types and selection
By suspension method there are the saddle type (used with a stay rod, common on conventional catenary) and the hook-head type (hooked on directly, compact in construction). By insulation there are insulated and non-insulated versions, and the groove diameter is matched to the messenger wire size (for example JTM-70/95/120/150). In selection check the cantilever tube diameter, the messenger wire size and the insulation requirement, and in tunnels and heavily polluted areas check the protection class. Chuangwit messenger seats are supplied to the current TB/T 2075 series and can be customised to drawing number.