MECHANICAL HANDLING ON CONSTRUCTION SITES

Too many buildings are still designed without thought to mechanised handling. But the common task of architects and site engineers is to cut handling time and save costs.

In the last few years, architects and engineers have realised that mechanical handling requirements should be incorporated into the design process. However, apart from general lifting and transport problems, specific design is difficult. Contractors often apply different methods of handling, as this depends on trailer and crane availability.

Mechanical handling during construction should be treated as a normal design parameter.

The elements of a building should be designed as the optimum solution for the building type, preferred method of construction and cost available, but should incorporate sufficient strength for all reasonable handling requirements.

In low rise work prefabricated roof trusses are plumbing "heart" units, and packaged handling by rough terrain forklift trucks and special machines.

Architects and engineers engaged on large projects realise that it is in their interest to minimise the weight of components to reduce cranage costs and to consider site access for delivery vehicles.

EXERCISES

I. Answer the following questions:

I. Why lifting and transport problems on the construction site must be taken into account by
architects? 2. Why is it important to minimise the size of structural elements? 3. How should
mechanical handling during construction be treated? 4. What does a method of handling depend on?5. How should the elements of a building be designed?

II. Read and translate the following word combinations and use them in the sentences of your own:

structural components; to cut handling time; to minimise the size; to reduce cranage costs; to consider site access for delivery vehicles

III. Translate the following sentences:

1.Architects have now realised that mechanical handling requirements should be incorporated. 2. It is important to minimise the weight of components to reduce cranage costs. 3. The lifting and transport problems during construction should be treated as a normal design parameter. 4. It is important to consider -site access for delivery vehicles. 5. The method of handling can depend on trailer and crane availability.

SELF-ERECTING TOWER CRANE GCI 5400

General Principles. The crane described is a completely self-contained mobile self-erecting hydraulic crane. This is a telescopic tower crane in the true sense of the word "telescopic". Not only is the tower telescopic, but also the boom, which can be fitted with lattice fly jib.Once on the site it is a completely self-contained unit, as it is constructed to form a semi-trailer requiring a tractor unit for its movement from site to site, and also its movement around a construction site. If the crane is to remain static for a couple of days the tractor unit can be taken away and used for some other purpose, thus increasing its utilisation. The overall length of the semi trailer in its transport position is 19.812 m. The only limiting factor concerning the choice of tractor units is that of its maximum height, which should be less than 2.807 m.

Manoeuvrability. The trailer has an overall width of 3.048 m, and the height has been kept down to an acceptable 4.102 m, for a crane that is able to lift to a height of nearly 77 m. Once the crane has been set in position and the forward stabilisers lowered to take the weight the tractor unit can be removed. As the rear outriggers have an overall spread of only 8.229 m centre to centre the GCI 5400 can be set up parallel with an existing building and within 3 m of it. Once the outriggers have been set up, the crane is ready for erection. On the GCI 5400 there are two engines, one supplying power for erection and one for the crane mo­tions. Mounted at the front end of the undercarriage is a diesel engine which develops 52 hp at 2,550 rpm and drives a single gear type pump supplying 80 litre / min. This pump distributes its oil to the outriggers, tower lift cylinders, tower extension

The Engine. The upper deck is mounted on a ball bearing turntable and is able to slew continuously through 360 deg. Mounted at the rear of this turntable is a Caterpillar 3208 diesel engine delivering some 165 hp at 2,400 rpm. This engine drives a three sec­tion Rear type pump which has a total output of 565 litre / min. All movements of the crane are hydraulically actuated.In corporated in the hydraulic system in the return line is a full flow filter with by­pass protection and replaceable cartridges. The boom is a three-section type which is hydraulically telescoped from 10 to 25 m. This boom can also be filled with a 12 m lattice type fly jib which is all part of the standard equipment. When erected the crane can be operated from either the cab, which is mounted on the upper deck, or from a remote control panel. The remote control panel is equipped with 50 m of cable as standard, so the operator can stand almost where he likes, on the ground or even up on a structure right next to where the load has to be placed.

Load Indicator. Incorporated in- the crane is a load moment indicator which warns the operator both audibly and by light when the operation approaches 90 per cent of the safe working load. If lifts are attempted beyond 100 per cent of the safe working load, all crane functions which can overload the machine are cut out. However the op­erator can still slew; retract or raise the boom to reduce the operating radius. All the rated capacities are based on structural strength and none exceed 66.33 per cent of the tipping load. There are certain restrictions. The crane must not be operated when the wind speed is in excess of 56 km/h, loads over 3,400 kg must only be handled in low hoist speed.

High Speed. Time taken for full erection with the boom lip to a height of.66 m is 16 min, which is pretty good when one considers that this crane is capable of lifting to that height a load of 9,080 kg. The maximum tower height is 42.6 m, and the maximum radius of the boom is 22.8 m at which the GCI 5400 is able to lift a load of 1,818 kg. This compares very favourably with many of the truck and trailer mounted tower cranes already in use.

EXERCISES

I. Answer the following questions:

1.What kind of crane is the GCI 5400? 2. How many engines has this crane? 3. What is the maximum lifting capacity of the crane? 4. To what height is this crane able to lift a load? 5. How does this crane move on a construction site?

II.Read and translate the following word combinations:

rated capacities; tipping load; load indicator; incorporated in the crane; certain restrictions; wind speed

III.Translate the following sentences:

1. This telescopic tower crane is a completely self-contained mobile self-erecting hydraulic crane. 2. The crane constructed is a semi-trailer requiring a tractor unit for its movement from site to site. 3. This crane can be set up parallel with an existing building and within 3 m. of it. 4. The controls for the erection of the tower are housed in a lockable box. 5. This diesel engine delivers some 165 hp at 2,400 rpm.

GLOSSARY

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