Tower Crane Operations
Tower crane types, trolley mechanisms, climbing operations, weathervaning, anti-collision systems, and wind speed limits.
- Describe tower crane fundamentals and major components
- Explain climbing operations and trolley mechanisms
- Define weathervaning and wind effects on tower crane operations
- Identify personnel hoisting requirements and anti-collision systems
Lesson 1
Tower Crane Fundamentals & Components
Tower Crane Types
Tower cranes are fixed-position cranes used primarily in building construction. Two main types exist:
Hammerhead (Top-Slewing)
Horizontal jib rotates at the top of the tower
Trolley moves along the jib to change radius
Most common type on construction sites
Counter-jib with counterweights on opposite side
Luffing Jib
Jib angle changes to adjust radius
No trolley - radius changed by luffing
Smaller swing radius needed
Used on congested sites
Major Components
| Component | Function |
|---|---|
| Mast (tower) | Vertical structure supporting the jib |
| Slewing unit | Allows rotation of the jib assembly |
| Jib (boom) | Horizontal arm from which loads are lifted |
| Counter-jib | Opposite arm holding counterweights |
| Trolley | Moves along jib to change load radius |
| Hook block | Suspended from trolley for load attachment |
| Climbing frame | Used to increase mast height |
Capacity and Radius
Tower crane capacity varies with trolley position (radius). Maximum capacity is at the minimum radius (closest to the tower), and capacity decreases as the trolley moves outward. The load chart for a tower crane shows capacity at various trolley positions along the jib.
Tower Crane vs. Mobile Crane
On a mobile crane, radius changes by booming. On a tower crane, radius changes by moving the trolley along the jib (hammerhead) or luffing the jib (luffing type).
Tower cranes use either a trolley on a horizontal jib (hammerhead) or a luffing jib to change radius. Capacity is greatest at minimum radius and decreases as the trolley moves outward or the jib luffs out.