Wrecking ball
Encyclopedia
A wrecking ball is a heavy steel ball, usually hung from a crane
, that is used for demolishing
large buildings. It was most common during the 1950s and 1960s. Several wrecking companies claim to have invented the wrecking ball. An early documented use was in the breaking up of the SS Great Eastern
in 1888-9, by Henry Bath and Co, at Rock Ferry on the river Mersey.
With the invention of hydraulic excavators and other machinery, the wrecking ball has become less common at demolition sites because its working efficiency is smaller compared to that of long reach excavator
s. Although the wrecking ball is still the most efficient way to raze a concrete frame structure, it is decreasing in use.
Wrecking balls range from about 1,000 lb to around 12,000 lb (450 kg to 5400 kg). The ball is made from forged
steel, which means the steel is not cast into a mold in a molten state. It is formed under very high pressure while the steel is red hot (soft but not molten) to compress and to strengthen it.
of the ball.
and more efficient or practical than wrecking balls, to destroy buildings. The most common use of blasting charges is to implode
a building, thus limiting collateral damage; see Demolition
. Wrecking balls are more likely to cause collateral damage, because it is difficult to completely control the swing of the ball.
Also wrecking balls are still used when demolition may not be possible due to local environmental issues or asbestos/lead building content.
Crane (machine)
A crane is a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of...
, that is used for demolishing
Demolition
Demolition is the tearing-down of buildings and other structures, the opposite of construction. Demolition contrasts with deconstruction, which involves taking a building apart while carefully preserving valuable elements for re-use....
large buildings. It was most common during the 1950s and 1960s. Several wrecking companies claim to have invented the wrecking ball. An early documented use was in the breaking up of the SS Great Eastern
SS Great Eastern
SS Great Eastern was an iron sailing steam ship designed by Isambard Kingdom Brunel, and built by J. Scott Russell & Co. at Millwall on the River Thames, London. She was by far the largest ship ever built at the time of her 1858 launch, and had the capacity to carry 4,000 passengers around the...
in 1888-9, by Henry Bath and Co, at Rock Ferry on the river Mersey.
With the invention of hydraulic excavators and other machinery, the wrecking ball has become less common at demolition sites because its working efficiency is smaller compared to that of long reach excavator
Long reach excavator
The long reach excavator or high reach excavator is a development of the excavator with an especially long boom arm, that is primarily used for demolition. Instead of excavating ditches, the long reach excavator is designed to reach the upper stories of buildings that are being demolished and pull...
s. Although the wrecking ball is still the most efficient way to raze a concrete frame structure, it is decreasing in use.
Construction and design
Modern wrecking balls have had a slight re-shaping, with the metal sphere changed into a pear shape with a portion of the top cut off. This shape allows the ball to be more easily pulled back through a roof or concrete slab after it has broken through.Wrecking balls range from about 1,000 lb to around 12,000 lb (450 kg to 5400 kg). The ball is made from forged
Forge
A forge is a hearth used for forging. The term "forge" can also refer to the workplace of a smith or a blacksmith, although the term smithy is then more commonly used.The basic smithy contains a forge, also known as a hearth, for heating metals...
steel, which means the steel is not cast into a mold in a molten state. It is formed under very high pressure while the steel is red hot (soft but not molten) to compress and to strengthen it.
Method of use
To demolish roofs and other horizontal spans, the ball is typically suspended by a length of steel chain attached to the lifting hook of a crane boom above the structure, the rope drum clutch is released and the ball is allowed to free-fall onto the structure. To demolish walls the ball is suspended at the desired height from a crane boom and a secondary steel rope pulls the ball toward the crane cab. The lateral rope drum clutch is then released and the ball swings as a pendulum to strike the structure. Another method for lateral demolition is to pivot the crane boom to accelerate the ball toward the target. This is repeated as needed until the structure is broken down into debris that can easily be loaded and hauled away. The demolition action is carried out entirely through the kinetic energyKinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
of the ball.
Modern equivalents
The advancement of technology led to the development and use of blasting charges, safer than dynamiteDynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...
and more efficient or practical than wrecking balls, to destroy buildings. The most common use of blasting charges is to implode
Building implosion
In the controlled demolition industry, building implosion is the strategic placing of explosive material and timing of its detonation so that a structure collapses on itself in a matter of seconds, minimizing the physical damage to its immediate surroundings...
a building, thus limiting collateral damage; see Demolition
Demolition
Demolition is the tearing-down of buildings and other structures, the opposite of construction. Demolition contrasts with deconstruction, which involves taking a building apart while carefully preserving valuable elements for re-use....
. Wrecking balls are more likely to cause collateral damage, because it is difficult to completely control the swing of the ball.
Also wrecking balls are still used when demolition may not be possible due to local environmental issues or asbestos/lead building content.