By Alex Dahm12 December 2008
Gillis, an engineer, has redesigned a tower crane concept patented by his father, Gaspard, in 1968. Patrick Gillis patented the new design in 2008. A primary characteristic of the large saddle jib type tower crane design is that it has two long jibs instead of a jib and counter jib. Another distinguishing feature is that the slewing mechanism uses a pair of propellers mounted at the end of each jib.
The unusual design allows the cranes to have a jib up to 150 m long on each side, giving a working diameter on the largest model of 300 m. Two jibs means, theoretically, that it is 50% more efficient than a conventional single-jib crane.
The cranes can also be rigged in a more conventional configuration, with a shorter single jib and counter jib carrying counter weight.
Target applications include concrete placement on large construction projects, repetive cycle lifting in seaports, mining and the steel industry. It is designed to be able to move industrial materials and heavy equipment.
In a spin
Driving the rotation from the end of the jib instead of at the slewing ring makes the vast jib length a viable proposition because there is no torsion force acting on the tower structure. A simpler structure that is easier to build is another feature of this design, Gillis says. The load does not swing to and fro and wind has no influence during rotation so the load can be placed accurately, Gillis continues.
Each propeller has its own variable speed drive and can be operated independently via a continuously variable transmission (CVT) in both directions. To maximise acceleration and braking power the pitch of the propellers can be altered by rotating the blades by up to 180 degrees. It makes sense to use this propeller principle on jibs longer than 50 m, Gillis says.
Advantages of the design are many, according to Gillis. "It optimises effectiveness, slewing speed, braking power and safety." Energy consumption is optimised by the propeller system being more efficient than a conventional system on longer jib lengths, according to Gillis. The propellers will range from 1.6 m diameter on the smaller models to 4 m on the largest. Power can be electric or hydraulic with a power pack.
Hoisting, which can also be electric or hydraulic, is variable from 0 to 200 m/min without load. Lifting capacity of the largest model, the 150/30EPH110, is 30 tonnes in four fall operation, out to a 30 m radius, lifting at up to 16 m/min. Capacity is 2.5 tonnes at 70 m radius, Gillis says.
Standard tower height is 60 m free standing for the double-jib configuration but can be 250 m with anchors in a single jib and counter jib configuration.
At the time of writing in late November, Gillis was looking for orders, financial partners and crane manufacturers to help take the project forward.