▌ APPLICATION NOTE · OCTOBER 2026 · TOWER HEAD AND PENDANTS Tower Head and Pendants: Tension, Alignment and Inspection At the top of the mast sits the tower head, a truss that gives the jib and counter-jib their support points. From it, pendants run out to hold the jib and back to hold the counter-jib. The head and the pendants are pure tension and compression: they do not lift the load, but without them the jib would not stay in its working position. This note explains how the tower head and pendants work, why alignment and matched lengths matter, and what should be inspected before erection and during service. The crane maker’s manual defines the pendant arrangement and inspection points.
01 THE HEAD AS AN ANCHOR The tower head is a welded truss that caps the mast. It carries the anchor points for the jib and counter-jib pendants and, on many cranes, the mounting positions for the hoist and trolley pulleys. Its shape sets the angle at which the pendants pull, and that angle is part of the crane’s design. Because it sits at the top of the mast, the head takes the pendant tension in compression and bending. Its welds and anchor pins are therefore structural details that deserve inspection, not just the parts that look impressive. ▌ CAPS THE MAST The head is a welded truss with pendant anchor points. ▌ SETS THE PENDANT ANGLE Its geometry defines the pull angle of the pendants. ▌ WELDS AND PINS MATTER The head carries pendant tension in compression and bending. 02 HOW PENDANTS CARRY TENSION Pendants are steel bars or rods with forged or machined end fittings and pins. They link the tower head to the jib and counter-jib and take the tension that holds those arms in position. Because they work in tension, their length and their end fittings are the critical features. Pendants are made up in matched pairs or sets. A pendant that is slightly too long or too short changes the angle of the arm it supports and redistributes load in a way the design did not intend. Mixing pendants from different sets is therefore a real error, even when they look similar. ▌ TENSION MEMBERS Pendants hold the jib and counter-jib by tension. ▌ LENGTH IS CRITICAL A pendant of the wrong length changes the arm angle and the loading. ▌ KEEP SETS MATCHED Do not mix pendants from different sets. 03 ALIGNMENT AND FIT Alignment starts at the pins. Pins should enter freely and be secured with the specified retainers. A pin that needs force to fit is a sign of misalignment, and forcing it damages the pin and the lug. The pendant should hang straight between its two anchor points without side load. The connection at the tower head and at the jib should be checked for gap, wear and correct pin retention. A pendant that is properly tensioned and aligned runs straight; one that is misaligned shows it as a bend or a side load at the fitting. ▌ PINS ENTER FREELY A pin that needs force indicates misalignment, not a tight fit. ▌ NO SIDE LOAD Pendants should hang straight between their anchor points. ▌ CHECK RETENTION Pin retainers must be fitted and secure at both ends.
04 INSPECTION POINTS Before erection, inspect the head for weld cracks, deformation and corrosion, and the pendants for straightness, thread and fitting condition. Pins and lugs should be checked for wear. Any pendant that has been bent should be replaced, not straightened. In service, the manual will define the inspection interval. The focus is on the pin connections and the end fittings, which are where wear and fatigue appear first, and on any sign of movement at the head. ▌ BEFORE ERECTION Check the head for cracks and the pendants for straightness and fitting wear. ▌ REPLACE BENT PENDANTS A bent pendant is replaced, not straightened. ▌ WATCH THE PINS Pin connections and end fittings show wear first. 05 WHY IT MATTERS The tower head and pendants are easy to overlook because they do not move and do not carry the load directly. But they hold the jib in the position the load chart assumes. If a pendant is wrong, loose or damaged, the jib is no longer where the design expects it to be, and the crane’s capacity and behaviour change. Treating the head and pendants as structural, inspected items rather than fixed fittings is the difference between a crane that is assembled correctly and one that merely looks assembled. ▌ THEY HOLD THE GEOMETRY Pendants keep the jib where the load chart assumes it is. ▌ NOT FIXED FITTINGS The head and pendants are inspected structural items. ▌ LOOKS ASSEMBLED IS NOT ENOUGH Correct tension and alignment are what make the assembly right. PROCUREMENT IMPACT ● Order tower head and pendants to the crane model and jib configuration. ● Specify pendant lengths as matched sets and keep sets together. ● Ask for pin sizes, retainers and fitting specifications with the parts. ● Include spare pins and retainers in the spares list. ● Confirm inspection intervals and weld inspection requirements. WHAT TO WATCH ● Watch for bent pendants, which must be replaced rather than straightened. ● Watch pin fit; force indicates misalignment. ● Watch for side load at the fittings, which shows as a bend. ● Watch weld condition at the head, especially around anchor points. ● Watch pendant sets, which must stay matched and complete. ABOUT ZN Industrial (Shandong Zhinuo) designs and manufactures crane safety monitoring systems, positioning systems and mechanical auxiliary handling equipment for overseas construction, industrial and steel markets. Standards and regulations vary by market — local rules still govern your site. ▌ CONTACT shandongzhinuo@outlook.com +86 176 6371 0314 · en.znaqkj.com SOURCES · crane maker’s manual · EN 14439 · ISO 12480-1 |
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Tower Head and Pendants: Tension, Alignment and Inspection
The tower head anchors the jib and counter-jib pendants. This note explains how the head and pendants carry tension, how alignment affects the crane and what to inspect before and during service.
