INTRODUCTION

On the 10th May 2016, we had gone to the Tenzin Heavy Machinery located at Shah

Alam. Tenzin’s was doing business for sales, rental, service of tower crane and passenger hoist.

During the visit, we were informed that the Tenzin’s we one of the biggest supplier for the tower

crane and the passenger hoist for a construction in Malaysia. They previous supplier involve in

the construction of KLCC Podium, KLIA Cargo Terminal, MTB project and many more. They

had being operated about 24 years till now. We had being given some information by the

engineer that responsible for the tower crane inspection, and erection by Encik Nik Nazirul

Amin. He had given us some technical briefing and information about the tower crane consists at

Tenzin’s. By this, we are able to differentiate three type of tower crane consists at Tenzin’ which

are Topless, Hammerhead, and Luffing tower crane.

Generally tower cranes are a common fixture at any major construction site. A crane is a

tower equipped with cables and pulleys that is used to lift and lower materials. Cranes are

commonly used in the construction industry and in manufacturing heavy equipment.

Construction cranes are usually temporary structures, either fixed to the ground or mounted on a

purpose-built vehicle. Cranes may either be controlled from an operator in a cab that travels with

the crane, by a push button pendant control station, or by infrared or radio control. Where a cab

operator is employed, workers on the ground will communicate with the operator through a

system of standardized hand-signals or, in larger installations, radio systems; an experienced

crew can position loads with great precision using only these signals. The largest revolving

cranes in the world can be found on crane.

Figure 1: Tower Crane Example.

The tower crane is a modern form of balance crane. Fixed to the ground, 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 sits in a cabin at the top of the tower. 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 pulleys.

A tower crane is usually assembled by a telescopic crane of smaller lifting capacity but greater

height, and in the case of tower cranes that have risen while constructing very tall skyscrapers, a

smaller crane will sometimes be lifted to the roof of the completed tower to dismantle the tower

crane afterward. A self-assembling tower crane has been demonstrated, which lifts itself off the

ground using jacks, allowing the next section of the tower to be inserted at ground level.

There are two major considerations that are taken into account in the design of cranes.

The first is that the crane must be able to lift a load of a specified weight and the second is that

the crane must remain stable and not topple over when the load is lifted and moved to another

location. The lifting capacity and the stability of crane are equally important to ensure the

balancing and prevent counter twisting.

TYPE OF TOWER CRANE AT TENZIN’S

a) Topless Tower Crane.

This crane knows as Topless since the upper part of the crane does not had any structure.

b) Hammerhead Tower Crane.

This crane is knows as Hammerhead Tower Crane because of the structure which look

and represent the image of hammer.

c) Luffing Tower Crane.

TOWER CRANE PART.

DEFINITIONS

i. Crane – Consists of a rotating structure for lifting and lowering horizontally on rubber

tires or crawler treads

ii. Hoist - Used to lift and lower load.

iii. Brake – To slow or stop motion by friction or power

iv. Jib – Extension attached to the boom point to provide added boom length for lifting

specified loads.

v. Boom angle indicator – An accessory device that measures the angle of boom base

section centerline to horizontal

vi. Load – The weight of the object being lifted including:

1. Load block and hook.

2. Wire rope.

3. Rigging.

4. Boom attachments.

5. Ancillary attachment.

vii. Pendants – Stationary wire ropes used to support the boom.

viii. Radius – The horizontal distance from the axis of the rotation of the crane’s

superstructure to the center of the suspended load.

ix. Superstructure – The rotating frame, gantry and boom or other operating equipment.

x. Counter weight – Weights used for balancing loads and the weight of the crane in

providing stability.

 TOWER CRANES ERECTION PROCESS The construction crew uses the tower crane to lift steel, concrete, large tools - like

acetylene torches and generators, and a wide variety of other building materials. The first process

of erecting a tower crane is by planting the fine angle (Fixing angle/foundation anchor). The base

of the tower section is first stacked to the foundation anchor (also known as fixing angle). Fixing

Angle of high quality cast iron act to serves to strengthen the foundation. Foundation anchors are

steel posts embedded in re-enforced concrete that are bolted to the tower. These anchors provide

a secure connection to prevent the crane from swaying or experiencing structural failure due to

overload and wind forces. Then next is by laying of the foundation. There are two types of

foundation used to on-site foundation cast and stacking foundation (installation of ballast block).

A Tower Crane Mast Section is then start set into a foundation with steel pedestals. The Mast

Section is plumbed to a degree of 1:500 (i.e. It must not deviate more than 1 inch from plumb for

every 500 inches vertical). Concrete is poured and then the crane is ready to be erected after the

curing of the concrete.

Once the base

or foundation is completed, is then erected and attached to it using a second crane or a self-

erection procedure (self-assembly). The first part of the tower section is placed. This part is

placed with the help of mobile cranes. The tower section is reinforced by a braced square or

truss. The sections are bolted together as the tower crane is erected. The bolts and pin between

the connection areas are normally inserted manually by the worker using a sledgehammer. There

also an access ladders are incorporated in the interior of the sections to enable workers to move

up and down the crane. The section is rise as high as approximately 12 meters.

Figure 4: Installation on site-cast foundation.

Figure 3: Stacking Foundation.

Figure 5: Section unit.

Figure 6: Sledgehammer.

Then the insertion of top climbing unit which is known as the climbing crane is placed

along with the tower section. This specialized section enables tower crane sections to be inserted

and connected to the tower. At the insertion section, there are monorails which provide the easier

for worker to pull the section inside the climbing unit. Then ,a large hydraulic system (hydraulic

cylinder) then lifts the Slewing Assembly, Jib, and Counter jib one tower section higher so that

another section can then be inserted. This is called as the jacking process. In this process, the

weight of upper part is 100% depend on the strength of the hydraulic cylinder. This is control by

special expertise which responsible to control the pump for controlling the hydraulic system.

Then the next part that combined with the other part is the slewing unit. The jib, counter-

jib, tower top, and slewing assembly collectively make up the slewing unit. This section allows

the crane to rotate and perform lifting.

Figure 7: Climbing Unit (climbing Crane).

Figure 7: Slewing Unit.

After the insertion of the slewing unit, the process of erection continued with the

installation of the tower top. Hammerhead or "high-top" cranes utilize a tower top section for

greater torque and stability. Pendant bars are attached from the tower top to the jib and counter-

jib that provides further stability. Anemometers and aircraft-warning lamps are placed on the top

of the tower.

Then the next process continued with the installation of boom (horizontal jib) and counter

jib. The jib extends horizontally at various lengths depending on the model and configuration of

the crane. A trolley attached to the underside of the jib moves loads in and out from the cranes

center axis. Hoist and trolley lines run throughout the jib enabling vertical and horizontal

movement of the load. Rotation of the jib is achieved by employing the "slewing" action.

Figure 8: Tower Top.

Figure 3: Horizontal jib (Boom)

Figure 4: Counter Jib.

A cranes drives, drums, gears, electronics, and counter-weights are found on the counter-

jib platform. Located behind the operator cab, the counter-jib provides a balancing force to the

load on the horizontal jib. Drives, drums and electronics are located to the rear of the counter-jib

to maximize torque and for ease of maintenance.

Figure 5: Pendant Bar.

Both the boom (jib) and the counter jib are connected with the pendant bar. The pendant

bars is used to provide additional stability to the crane. The bars are attached from the tower top

to the jib and counter-jib. After the complete installation, there will be an officer that will come

and inspect to see whether the cranes in safe to used or not.

The height of the cranes raise is adjusted according to the height of the building. The

climbing crane will lift the cabin upward so there will be an enough space between the mass

sections. The boom will raise the section to put it in the hollow space. Before the insertion of the

pin, the boom will uplift another mass section and he correct center will be adjusted so that the

pin hole is correct position and at the same time to provide the balance for the crane. The process

will be repeated continuously until desired height is achieved. The final process to make the

crane operational is to set the motion limits for the hoist and trolley, followed by performing a

load test to 100% of the cranes capacity.

CONCLUSION

As a conclusion, the objective of this site visit was mainly to familiarize ourselves with

the type and the operations of machinery while at the same time learning new things is achieved.

This is a good experience for us to explore and understand more about equipment used and their

function at the site and also being able to known how the machine functions on-site. We were

able to feel the real situation in workplace and challenges faces during construction process.

There many benefit for us that we can get as a civil engineering technologies student regarding to

this site visit. This site visit teaches us and helps us to relate the theory and practical involved in

the subject we learn

During the site visit, we had being told and motivated by the CEO of Tenzin’s which is

Datuk Eric. Datuk Eric said that in order to become a successful engineer in the future and to be

a successful entrepreneurs like him, we had to learn from the bottom. And the most important is

to have a good team work. A good teamwork and team building will strengthen the company in

every aspect. Within this we will learn that works well together understands the strengths and

weaknesses of each team member. One of the benefits of strong teamwork in the workplace is

that team leaders and members become proficient at dividing up tasks so they are done by the

most qualified people. Without strong teamwork, it can be difficult for managers and executives

to determine which staff members can best accomplish job tasks. Same as student, we had to

learn this so that we will understand what is the meaning of complement each other.

Besides, Datuk Eric also said that a good team work and teams develop systems that

allow them to complete tasks efficiently and quickly. When a task is handed to a well-trained and

efficient team, the team's work pace assures that the task will be completed quickly and

accurately. This allows the company to take on more work and generate more revenue without

having to add more staff. This becomes helpful when efficient teams from different departments

work together. Each team is well aware of its own abilities and the groups can work together

effectively as opposed to disjointed groups of employees who may not be familiar with how to

work together.

He also remind us that, for the upcoming future, there are many challenges each day in

any workplace, and a strong team environment can act as a support mechanism for staff

members. Work group members can help each other improve their performance and work

together toward improving their professional development. Team members also come to rely on

each other and trust each other. These bonds can be important when the team faces a particularly

difficult challenge or if the group is forced to deal with the loss of a team member while still

trying to maintain productivity. So in order for us to be successful in the future, we had to learn

the basic need first from now on.

Same as Douglas MacArthur has said, a true leader has the confidence to stand alone, the

courage to make tough decisions, and the compassion to listen to the needs of others. He does

not set out to be a leader, but becomes one by the equality of his actions and the integrity of his

intent.

As a recommendation, this type of site visit should been done more to exposed student

with related field. It is a good bridge for student to improve our knowledge regarding the skill

and apply the theory that had been learn. Thus this would help us to identify the skill and

responsibilities as technologist on site. This also should be an integral part of the subject.

.

REFERENCES

1. http://www.morrow.com/parts

2. https://sanggapramana.wordpress.com/2010/11/20/memasang-dan-membongkar-tower-

crane/

3. https://www.youtube.com/watch?v=YUtLQWoKpQ4

4. http://bestananda.blogspot.my/2014/07/cara-merakitmemasang-tower-crane.html

5. http://www.craneblogger.com/crane-resource-library/how-are-tower-cranes-built/

6. https://en.wikipedia.org/wiki/Crane_(machine)

7. http://science.howstuffworks.com/transport/engines-equipment/tower-crane1.htm

8. http://www.brighthub.com/education/homework-tips/articles/44062.aspx