When referring to cranes and maneuvers that are carried out to assemble, disassemble and hoist a tower crane must comply with the protection and safety manuals; adhering to strict control in each of the steps to be taken.
- 1 Crane tower assembly
- 2 Assembly required
- 3 How are cranes set up?
- 4 Tower crane jacking process
- 5 Steps for the assembly of a tower crane
- 6 Crane operation safety
- 7 Crane safety procedures
- 8 Crane safety signs
- 9 Tower crane safety
- 10 Tower crane safety checklist
- 11 Tower crane disassembly
- 12 Crane outrigger safety
- 13 Disarmament and carriage
- 14 Applications of cranes and maneuvers
- 15 Tower crane manufacturers
- 16 How do you assemble a tower crane?
- 17 Tower crane Operator
Crane tower assembly
Once the components of the tower crane have been unloaded on the construction site, it is assembled.
This process consists of erecting and mounting the crane on its site and foundations, in such a way that it can be able to provide the function for which it was designed.
The assembly and disassembly personnel must respect all the recommendations contained in the manufacturer’s manual, which must be complemented with the instructions given in writing by the professional responsible for the assembly (university professional or technician with experience in the assembly of tower cranes). Special care must be taken with prevailing weather conditions.
The written order emanating from the professional in charge must contain at least the following information about the crane:
- Brand, type and model.
- Mounting heights, initial and final, expressed in m.
- Pen and counter-feather length expressed in m.
- A number of elements, position, dimensions, and mass of the necessary air counterweight.
- Characteristics of the initial and final weights (geometry, dimensions, mass, and ordering).
- A number of branches of the lifting cable.
- Supply voltage and a section of the conductors.
- The bracing program, if applicable, in case the height of autonomy is exceeded.
How are cranes set up?
With regard to the fact that the cranes and maneuvers need stability conditions, before starting the assembly of a tower crane, the following must be done:
A study of the soil mechanics of foundation.
The construction of the basal ballasts and aerial counterweights according to the technical specifications of the assembly manual can be metallic, concrete or bulk materials, in which case they must be contained in a closed and sealed metallic box.
The counterweights and ballasts formed by blocks must bear a mark printed in easily legible and indelible characters, indicating the mass of the same. Each time the crane is assembled, the mass of the counterweight to be used must be verified, and these must always be secured to the structure of the tower crane.
The correct construction of the anchors and their consolidation.
The construction of foundations that adequately transmit maximum gas to the ground, these must be calculated and designed by competent university professionals.
The rails and other elements that are part of the road must be installed according to the provisions of the manufacturer, the fastening of rails must be appropriate to the materials of the structure that supports them.
Tower crane safety precautions
For the use of cranes and maneuvers, the tolerances admitted in the initial installation of the straight and horizontal roads will be the following:
Longitudinal leveling: The surface of translation of the same line of rails, must not present irregularities of a level higher than 1/1000 of the width of the track.
Transverse leveling: The difference of the height between the two lines of rails of the same track, should not be greater than 1/1000 of the width of the track.
How to build a tower crane?
Distance between axis:
The gauge and the tolerances must correspond to those specified in the manuals of the crane manufacturer, the head of each rail must be between two parallel vertical planes, whose separation is equal to the nominal width of the said head plus 5 mm.
- The slope between rail joints: Must be 2 mm maximum
- Separation of rail joints: Determined according to the dilatation calculation of the rail
- Transverse leveling of the foot of each rail: It should be 3 / 1,000 maximum, with respect to a horizontal plane
- State of the track of translation: The flat surface of the head of the rail, must be centered with respect to the plane of symmetry of the same.
Rolling tower cranes must have adequate means of immobilization to avoid any movement when exposed to the action of the wind. These means must be established according to the specifications contained in the manufacturer’s manuals.
Tower crane jacking process
In general, the process begins with the assembly of the base of the tower, then the first section is placed, with the diagonals that join it to the base and a part of the basal ballast, then the slide is installed on top of it. locate the tower head and the cabin.
Then the pen and counter jib are placed. The final counterweight is mounted and more basal ballast is added. New sections are installed with the help of the boom of the crane until reaching its final height.
Another way to increase the height is by means of a system in which the tower-cabin-head unit is smaller in section than the rest of the shaft. The new section that has an open side is superimposed on the tower surrounding the upper unit.
Then it goes up inside this new section, newly armed.
Steps for the assembly of a tower crane
- After the assembly of the cart and the basal ballast, the climbing equipment is prepared.
- The climbing equipment is mounted on the base section of the tower.
- The rotating part is assembled, including turning track, cabin, tower head and climbing section, joining the assembly tower.
- The counter jib is placed.
- With the hook of the crane, the tower section is placed on the mounting crosspiece.
- The elements of the climbing system. The assembly tower, the hydraulic equipment, and the support sleeper
The assembly systems have improved remarkably over time, in order to make it faster, more comfortable and simpler, thus reducing the cost of this operation.
The assembly of all the assemblies is done by means of quick joints that do not require the previous alignment.
In addition, the climbing is done by the hydraulic drive and the operators perform all their work from safe and robust platforms, making the whole process even in large capacity cranes very fast.
Forms of Operation: There are basically three possibilities of operating a tower crane:
- Through keypad
- Using joystick built into the command chair
The first two systems allow remote operation; that is to say; they allow the operator to move to the same point where the work is done, thus achieving greater security in a certain operation.
Usually, when visibility permits, it is operated directly from the command cabin, moving either the keypad or command box of it. And with the help of the signalman, it is possible to make the required movements.
The lever command systems indicated above have the following operating movements:
- Start-up of the crane
- Warning horn
- Load upload (First, Second and Third speed)
- Lowering of load (First, Second and Third speed)
- Translating the distributor car forward (First and Second Speed)
- Translation of the distributor car backward (First and Second speed)
- Turn to the right (First and Second speed)
- Turn to the left (First and Second speed)
- Translation on rails forward
- Translation on rails backward
- Emergency stop
The operation of a tower crane must be carried out by a person who duly certifies his professional capacity. Requirements to be a crane operator:
The operator of a tower crane must have a basic knowledge of the assembly, operation, safety and maintenance conditions of a tower crane, as well as the knowledge necessary to interpret the manual and other technical documents provided by the manufacturer of the tower crane, to enable it :
- interpret a load chart
- know clearly the importance of the safety mechanisms of each crane
- its function and its normal location
- know the importance and behavior of steel cables and know how to put the crane into service correctly.
It is recommended that the handling of the crane is only entrusted to people over 18 years of age, who have a minimum level of schooling, who have passed a psychometric test, equivalent to the driver class A2, absence of diseases incompatible with work, have a high degree of vision and hearing, insensitivity to vertigo and good reflexes.
They must also attend a training course (in Operators and Requirements and responsibility, it was established that the operators that have more than one year of duly accredited professional experience, will be able to opt for the corresponding training or professional accreditation of 25 hours and the operators 25 that have been started after 1999 must attend a course of 150 hours, after which they will obtain a card) and undergo periodic medical examinations (worrying exams).
Crane operator responsibilities
At the beginning of the working day, the operator must make and record the following verifications:
- Check that the rails are aligned and correctly secured.
- See that the road is free of obstacles.
- Control the consolidation and alignment of the basal ballast and the counterweights.
- Observe possible oil leaks in the gearboxes.
- Check the operation of the controls of the tower crane, operating it without load.
- Check the good condition of the travel limiters of the carriage and the hook.
- Check the condition of the steel cables.
- Verify the proper functioning of the safety lock of the hook.
- Verify that the handle of the straps has not suffered wear or deterioration in the weld
- that the components of the closing of the gate of the mats work correctly, verifying especially, the absence of round fluted construction iron in any supporting element.
- Verify that the flanges do not have cuts or other damages.
- Inspect the metal structure to detect possible bends or deformations of its components.
- You should worry about the order and cleanliness of the cabin, the walkways, the ladders, and the rails.
In case of any anomaly or damage, the crane operator must stop the tower crane and immediately inform his superior.
During the execution of the entire work, a daily report must be kept in which the time worked and the operational news is recorded.
Crane operation safety
When the conditions of vision are not optimal for the operator, he must obligatorily request a signalman to the work for the help of the cranes and maneuvers.
The signalman must know the international code of signals for the operation with tower cranes, which is based on indications with hands and arms.
The signals of this code are regulated by the Tower Cranes Standard. Operating conditions and to be directly understood with the operator of the tower crane.
This code is formed by simple signals, easy to execute and interpret and that also does not produce physical exhaustion since the movements are natural and logical.
Crane safety procedures
Signal Technique: When crane and maneuvers are used, the technique of these signals is mainly based on the following:
- A hand on the waist indicates working at normal speeds, in any maneuver.
- A hand on the chest indicates working at slow speed, in any maneuver.
- The two hands up to indicate normal stopping.
- The two hands on the sides mean stop immediately.
- All signals must be executed calmly and safely, any doubt or acceleration of a signal will only confuse the operator.
- The signalman must be careful to always be in sight of the operator of the crane.
Crane safety signs
The signals that are normally used are:
- I take the command.
- Upload normal.
- Upload slowly.
- Download normal.
- Normal right turn.
- Right turn slow
- Truck on the right with normal speed.
- Truck on the right with high speed.
- Normal detention
- Car on the left with normal speed.
- Car on the left with high speed.
- High of urgency.
- Change of branch.
- End of command.
In important works, it is also recommended to have a radio communication system, to complement the corresponding orders to the operator as far as the tasks to be done and their correlative order; in this way, the isolation is avoided when the operator works in the cabin.
Tower crane safety
Interruption of work: The cranes and maneuvers, are very sensitive to the wind and whenever this exceeds the speed of 64 km/hr, or even if the wind has a lower speed and loads of large surface are handled, the work must be paralyzed, leaving the pen in ” weathervane “, so that it does not resist the wind and, therefore, its overturning does not occur.
The work of the crane must be interrupted in the face of adverse weather conditions such as presence of frost, when it represents an overweight due to accumulation in the structure or hinders the descent of the hook when it is empty; also when there is no good visibility due to the presence of fog and the proximity of an electrical storm.
Reasons: The work of the crane must also be interrupted by anomalies in the installation or in the operation, such as:
- A bad condition of the lifting cable or flanges.
- The poor winding of the lifting cable in the drum.
- Intermittent power supply and/or loss of phase symmetry.
- Defects in the braking operations of some movement of the crane.
- Loss of lead in the structure.
- Lack of adequate lighting.
Tower crane maintenance
Maintenance work must always be carried out with the crane disconnected. Maintenance work that can not be carried out from the ground, must be done from scaffolding or appropriate platforms.
If the maintenance work can only be carried out with the crane in operation, it must be ensured that:
- There is no risk of a person being trapped or falling.
- The people who must carry out this work move away from elements through which the electric current passes.
- These people can communicate with the crane operator by word or by means of signals.
Tower crane safety checklist
The cranes and maneuvers that are made with electrical energy must be verified by a specialist before the first putting into service or before being put back into service after having been subject to major modifications. Cranes with a load capacity greater than 1000 Kg must also be verified.
The verification prior to the initial commissioning of a new crane is not necessary if the crane has already been verified beforehand and is accompanied by the corresponding documentation.
According to their own characteristics and local circumstances, the cranes must be checked by a specialist at regular intervals, but at least once a year. In addition, tower cranes must be inspected by authorized persons whenever they are assembled or when their characteristics change.
Registration of verifications The results of the verifications according to the above must be recorded in a verification book that can be consulted at the request of the researcher.
Maintenance costs have always been a concern and progress is being made on a continuous basis in the reduction of lubrication points and in the placement of materials that allow space to be maximized in maintenance operations and incorporating components that do not require maintenance.
Tower crane disassembly
To start the dismantling of this crane we must first have the right personnel to carry out this work, that is to say, that each person has the relevant safety talks, safety elements, and work disposition.
Once the supervisor has checked the conditions of the ground, you can determine with what support crane you should proceed to do this work considering the height and the radius.
Once you have all the aforementioned, the first thing to do is to dismantle the tower crane the number of sections, which are necessary for the reach of the auxiliary crane.
With the lifting cable of the tower crane, the pass must be made that allows the aerial ballast to be removed. Depending on the length of the boom of the tower crane, a ballast is left or not in the counter boom.
Then the lifting and carriage cables are removed to leave the boom released from these elements, then the passes are made with the lifting cable between the boom and the turret.
Crane outrigger safety
With the cranes and maneuvers you must have an auxiliary crane, that the pen has to be locked in the points that allow the balance of this piece, when it is fully in the air it must be hoisted a bit with the auxiliary crane in such a way, that it releases a little the traction exerted by the piece due to weight effect.
Then with the lifting of the crane must be tensioned to remove the pins that join the strut of the pen with the turret, achieved this lowers the elevation until the strap is completely housed on the back of the pen, at that time you can remove the fastening pins.
So that the feather is totally in the air, ready to lower it to earth, and in this way make its subsequent disarming and loading on trucks.
Disarmament and carriage
Then the air ballast should be removed according to the length of the pen should be left, so that this serves as a counterweight before removing the pen, then removed the counter-feather, stroking this piece with the auxiliary crane stands up to remove the pins of the braces and then remove the pins of subjection of the counterjib, and take it to earth for its later disarming and loading.
After the turret was broken in the upper part, the connecting bolts of sections are removed and this piece is ready to take it to earth.
Next, the scaffolding and the hydraulic pump must be removed from the center of the tower, then the track seat or cabin section of the upper part must be damaged, the bolts must be removed, and this piece must be grounded. After this, the tower sections can be removed according to the need and capacity that is required at that moment.
Now we proceed to remove the basal weights, if the tower crane is in the simply supported version, then the diagonals are removed joined by a pin at each end, this way the basal section is left free, to remove this piece and able to carry out the dismantling of the chassis that is also joined by tower connection bolts.
Finally, the connection is made from the earth that is usually on one side of the crane chassis, an evaluation of the work is made and a report is finally drawn up for this work.
Applications of cranes and maneuvers
There are different systems and sizes of cranes and the technical requirements that these cranes must meet are not the same in all countries.
The most commonly used cranes are the quick application cranes that move as a compact unit and can be assembled without the need for other auxiliary means.
Tower crane manufacturers
Tower cranes in the world:
- Europe and Germany represent the largest construction market.
- In Southeast Asia and the Far East market, almost exclusively turntable cranes with needle boom or articulated boom are used almost exclusively.
- In the construction of tall buildings, telescopic cranes are preferred, since in this field it is almost impossible to use a tower crane and its complicated assembly is not so relevant since labor is less expensive in this region.
How do you assemble a tower crane?
When referring to cranes and maneuvers that are carried out to assemble, disassemble and hoist a tower crane must comply with the protection and safety manuals; adhering to strict control in each of the steps to be taken. Once the components of the tower crane have been unloaded on the construction site, it is assembled.
This process consists of erecting and mounting the crane on its site and foundations, in such a way that it can be able to provide the function for which it was designed.
The biggest difference between mobile cranes and tower or fixed cranes is their mobility. As their names suggest, fixed cranes are fixed to a single spot once they have been set up. Whereas, mobile cranes can be moved as needed. The mobility of a mobile crane holds many advantages for any construction site.
The tower crane is a fixed Crane and has to be mounted On-Site. The Tower Crane presents itself like a vertical metallic structure having a horizontal boom that can turn over an angle up to 360°.
There are some prerequisites you need to attain to be a crane operator. The initial training is your initial step. You still have to go through rigorous apprenticeship training that usually lasts about 1 to 4 years, though you will be paid for doing the apprenticeship training.
Most crane operators get their experience through on-the-job training or apprenticeships. Apprenticeship candidates generally must be 18 years or older, have a school diploma or equivalent and be in fit physical condition.
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Radio remote controls are now standard equipment on most self-erecting tower cranes and are even becoming common in some parts of Europe for a flat-top tower crane.
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