Sunday, April 15, 2012

Comparison of marine airbag and SPMT for heavy load out

Marine airbags are often called ship launching airbags that indicates they are most used for launching ship into water. Inspired by ship launching, people developed many applications of marine airbags in different fields, the most remarkable one is heavy lifting and moving with marine airbags.
SPMT stands for self-propelled modular transporter, a platform vehicle with a large array of wheels; it is equipped with Power Pack Unit which provides the propulsion.
Obviously marine airbags are not as famous as SPMTs in heavy lifting and transport fields. The main reason is that marine airbag is not a high developed industry product yet; its ISO standard was issued only at 2011 years. Due to special manufacture technology marine airbags can only be made in China which also limited its worldwide development.
Marine airbags heavy lifting and load out has similarity with SPMTs but more difference. A comparison may help people to know their individual characters.

Heavy Lifting

Lifting Capacity
The SPMTs consist of four-axle units or six-axle units, the maximum allowable axleline payload is 30 tons per line. Then we can know:

Marine airbag’s lifting performance is decided by its working height and inner pressure.

Airbag specification Load Lifting height Airbag pressure
1.0 ×15 m 471 tons 0.5 m 4 bar
1.5 ×15 m 235 tons 1.0 m 2 bar
2.0 ×15 m 420 tons 1.0 m 1.8 bar

Provided there is a caisson with follow dimension needs to be lifted.

Length(m) Width(m) Height(m) Weight(t)
20.45 13.45 17.3 2357

To lift this caisson at 0.5 m high from ground people may choose 6 pieces airbags (1.0×15 m). The total 6 pieces airbags’ lifting capacity is 422×6=2533 tons. Air bags can be positioned with 4 m space.
To lift this caisson with SPMTs, people will need 2357/180=13 units 6 line modules but the structure dimension decides maximum 12 units modules can be deployed. Then SPMTs is not suit for this caisson lifting and moving.

Article from : Marine airbags VS. SPMTs

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