For example, the hoisting gear of the new Wolff 235 B can positioned on the jib instead of the counter jib, as is typical.
“This makes it possible to reeve the hoisting rope on the ground and thus completely pre-assemble the entire jib,” explains Wolffkran product manager Wouter van Loon. “As well as being very convenient and safe, it is also a novelty for luffing jib cranes of this size.”
The Wolff 235 B is designed for high volume concreting work on city centre high-rise buildings. It replaces the Wolff 224 B and ranks between the hydraulic Wolff 166 B and the next larger Wolff 275 B in the lower load moment range.
When setting about designing the new model, the engineers were as focused on its assembly and maintenance characteristics as they were on lifting prowess, since that is what customers demanded.
“The Wolff 235 B was developed in close collaboration with Wolffkran customers from the UK, who have decades of experience in handling luffing cranes on inner-city construction sites,” Wouter van Loon says. “The result is a Wolff with a proven duty chart that is unrivalled when it comes to assembly and versatility.”
The luffing gear can be mounted either on the counter jib or on the tower top during the assembly process, which offers more flexibility with regard to the size of the mobile crane. The second option has the advantage that the entire tower top including the hoisting gear with pre-reeved pulley block can be transported and lifted onto the crane as a single unit, which is an enormous time saver.
“In addition, the cabin platform with the Wolff Cab and switch cabinet can be placed on the empty counter jib during transportation,” says van Loon.
Maintenance concerns drove the decision to use an identical winch for both the hoisting and the luffing gear. The designers opted for the tried and tested 60 kW winch Hw 1160 FU that is used in numerous other Wolff crane models, which is also the case for the slewing gear and the frequency converters that are used in the 235 B.
Further features facilitating maintenance include the adoption of maintenance-free multi-disk brakes and the positioning of the luffing gear at the bottom of the tower top.
The Wolff 235 B offers a maximum load capacity of 8 tonnes in single-fall and 16 tonnes in two-fall operation and jib lengths from 30 to 60 metres. With a 50-metre jib, where it is designed to deliver its best performance, it has with a tip load capacity of 4.1 tonnes.
It can reach a maximum freestanding height of 82 meters using standard components from the modular Wolff tower system.
Thanks to its active absorber, the Wolff 235 B achieves a smaller minimum jib working radius of 10% of the jib length. The steeper jib position means that the load can be picked up closer to the tower, which can be a benefit on cramped city construction sites, as delivery trucks can be unloaded closer to the crane and loads do not have to be lifted over adjacent roads.
For the Wolff 235 B, the crane control has been enhanced with a brake testing function allowing the main and secondary brakes to be tested independently of each other.
Also standard are the Wolff Link remote diagnostic and maintenance tool, with real-time display of the crane operator’s monitor, fine drive modes and automatic power optimisation for the hoisting and luffing gear, an anti-collision interface, as well as the Wolff Boost function, which increases load capacity by 10% by slowing the speed down.
Wolff has always had a strong presence in the UK market. Hewden Tower Cranes (HTC), once the UK’s largest tower crane hire fleet, was entirely Wolff cranes and Hewden was Wolff’s exclusive dealer for the UK. This arrangement continued after PC Harrington acquired Hewden Tower Cranes in 2002. After Harrington fell into administration in 2015, the crane manufacturer took over the UK crane hire business and later made HTC boss Duncan Salt, formerly of Laing O'Rourke and Select Tower Cranes, chief executive of the entire group.