WEL COME

HYDRAULIC CRANE

Prepared by

Ghadiya Vishal N.

HistoryThe crane for lifting heavy loads

was invented by the Ancient Greeks in the late 6th century BC

Since these holes point at the use of a lifting device, and since they are to be found either above the center of gravity of the block, or in pairs equidistant from a point over the center of gravity, they are regarded by archaeologists as the positive evidence required for the existence of the crane.

Lifting such heavy weights in a concerted action required a great amount of coordination between the work groups applying the force to the capstans.

IntroductionHydraulic cranes are heavy equipment used

primarily for lifting. There are two basic necessities of their design: they must be able to lift a certain amount of weight and they must be able to do so while remaining stable. While cranes have been used throughout the centuries these days they feature a more technical design and there are several different types available.

In order to lift such heavy loads, hydraulic cranes make use of three important parts, the lever, the pulley, and the hydraulic cylinder.

There are several different types of hydraulic cranes, and knowing the differences between them can help you to choose the best one for you.

Mechanical principlesCranes can mount many different

utensils depending on load (left). Cranes can be remote-controlled from the ground, allowing much more precise control, but without the view that a position atop the crane provides.

The stability of a mobile construction crane can be jeopardized when outriggers sink into soft soil, which can result in the crane tipping over.

There are three major considerations in the design of cranes. First, the crane must be able to lift the weight of the load; second, the crane must not topple; third, the crane must not rupture.

Hydraulic Crane workingHydraulics is the science related to the behavior of

fluids, whether static or dynamic, and the practical uses derived there from. A surprising amount of our current technology is based on hydraulic principles, especially that used in our larger machinery, from automobiles on up.

Hydraulic machines take advantage of one consequence of this principal: the fact that any force applied to an incompressible liquid will propagate through the liquid, without significant loss of strength, to effect whatever's on the other side.

You press on a column of incompressible liquid here, and it makes something move over there.

Armstrong Hydraulic Crane He developed his ideas for a

hydraulically operated crane based on the hydraulic jigger, comprised of a ram in a closed cylinder arranged with multiple pulley sheaves at each end so as to multiply movement of the free end of a chain or rope wound around the sheaves when a pressurized fluid, normally water, was admitted into the cylinder.

His first working model was used at Newcastle with pressure from the street water pipes. It was so successful it attracted interest from railroad and dock shipping companies. Armstrong soon started building these cranes with his new Elswick Engine Works.

Lifting capacityThe lever. A balance crane contains a

horizontal beam (the lever) pivoted about a point called the fulcrum. The principle of the lever allows a heavy load attached to the shorter end of the beam to be lifted by a smaller force applied in the opposite direction to the longer end of the beam.

The pulley. A jib crane contains a tilted strut (the jib) that supports a fixed pulley block.

The hydraulic cylinder. This can be used directly to lift the load or indirectly to move the jib or beam that carries another lifting device.

Stability

For stability, 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 (called the "rated load" in the US) is some value less than the load that will cause the crane to tip.

Under US standards for mobile cranes, the stability-limited rated load for a crawler crane is 75% of the tipping load.

Standards for cranes mounted on ships or offshore platforms are somewhat stricter because of the dynamic load on the crane due to vessel motion.

DescriptionDynamic loads have to be taken into account in

the strength dimensioning of the structure of cranes. Such loads are due to the accelerations and retardations of the boom system itself and particularly those of a load to be lifted.

The highest permissible speed of the boom system of a crane has been determined by a hydraulic pump providing a volume flow set to a predetermined maximum level specific for each particular crane.

A serious drawback has been that the greatest permissible load and speed of the crane have been fixed and independent of each other.

Parts of a Hydraulic Crane Although everything on the truck begins

and ends with the hydraulic system, there's more to a hydraulic truck crane than the hydraulics.

Boom Jib Rotex gear Outriggers Counterweights Reinforced-steel cable Hook

BOOMThe most recognizable

part of any crane is the boom. This is the steel arm of the crane that holds the load. Rising up from just behind the operator's cab, the boom is the essential piece of a crane.

JibSome booms are

equipped with a jib, which is the lattice structure attached to the end of the boom. On the 70-ton hydraulic truck crane, the jib is 67 feet (20.4 m) long, giving the crane a total length of 194 feet (59.1 m). As the load is lifted, the sections telescope out to the desired height.

Rotex GearUnderneath the

operator's cab is a Rotex gear on a turntable bearing that turns at 2 revolutions per minute (rpm). It is driven by a bidirectional, hydraulic motor mounted on the cab and housed in a metal cover to prevent injuries. The rotation is controlled by a foot-operated, hydraulic pedal in the cab.

HookHydraulic hook

systems allow for simplified cable routing along the belly of the aircraft, and snagging or damage to the cable will not lead to accidentally dropping the cargo.

Hydraulic Crane Safety Devices Hydraulic crane manufacturers typically fit their

cranes with a number of safety components that are meant to increase safety while the crane is in operation. Steel reinforced cabs, anti-current and anti-upset devices are components that increase safety while hydraulic cranes are in operation.

Anti-current products prevent operator electrocution when crane components come in contact with a live power source, most frequently, active power lines.

Anti-upset additions to hydraulic cranes prevent tipping. Reinforced cages surround the cab of many hydraulic cranes to protect the operator during instances where a workload comes crashing down on them.

Hydraulic Crane Operating Safety TipsDuring crane operator training sessions,

hydraulic crane operators are informed on many safety measures that can be taken to decrease the risk of injury while a hydraulic crane is lifting a workload.

Hydraulic cranes are manufactured to lift loads within a specific weight range. Overloading a hydraulic crane greatly increases the likelihood of upset, which is why they should never be overloaded.

Working parts 1.A Hydraulic Crane in its simplest form consist of a Vertical

Post,Tie and Jib having Guiding Pulleys.All these parts are basic requirment of a Hydraulic Crane.

2. A Jigger is provided near the foot of Vertical Crane Post.The Jigger consist s of a fixed Cylinder,having a Pulley Block and containing a Sliding Ram.One endof the Ram is in contact with Water and other carries a Pulley Block.

3. A Chain or Wire Rope,one end of which is fixed,is taken round all the Pulleys of the two Blocks,through the Vertical Post and finally over the Guide Pulleys.

4. A Hook is attached to the other end of the Rope for handling the Load.There is a pipe connection for supplying water under High Pressure to the fixed Cylinder of the Jigger.

Advantage1. Hydraulic cranes use a fixed system of pipes,

constant pressure can be maintained once a part of the system has been moved into place, and this makes them extremely stable in use, and able to support relatively large weights.

2.Hydraulic cranes are amongst the simplest systems that you can use within any industrial process, and are very easy to maintain.

3. Most hydraulic cranes are comparatively light weight, and the ease with which they can be moved from one area to another within the factory or distribution center.

4. . There are a variety of different hydraulic cranes on the market, and they serve several different purposes.

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