Crane Research

• Large anchor bolts embedded deep into this pad support the base of the crane. cranes are essentially bolted to the ground to ensure their stability
• The crane cannot lift that much of weight if load is at the end of the jib. the closer the loads is positioned to the mast the more weight the crance can lift saftley.
  
• The tower crane is a modern form of balance crane. Fixed to the ground (or “jacked up” and supported by the structure as the structure is being built), tower cranes often give the best combination of height and lifting capacity and are used in the construction of tall buildings. To save space and to provide stability the vertical part of the crane is often braced onto the completed structure which is normally the concrete lift shaft in the center of the building. A horizontal boom is balanced asymmetrically across the top of the tower. Its short arm carries a counterweight of concrete blocks, and its long arm carries the lifting gear. The crane operator either sits in a cabin at the top of the tower or controls the crane by radio remote control from the ground, usually standing near the load. In the first case the operator’s cabin is located at the top of the tower just below the horizontal boom. The boom is mounted on a slewing bearing and is rotated by means of a slewing motor. The lifting hook is operated by a system of sheaves.

• In order for a crane to be stable, the sum of all moments about any point such as the base of the crane must equate to zero. In practice, the magnitude of load that is permitted to be lifted the “is some value less than the load that will cause the crane to tip.