Over its many decades Manitowoc has continuously introduced technology that changes how construction happens, bringing progress to communities around the globe. One of the latest examples is VVH technology, which can be found on the current Potain MRH and MCH luffing jib cranes. This innovative concept uses hydraulic power to replace the wire ropes traditionally used for moving the crane’s jib in the vertical axis. One immediately eye-catching advantage is that it eliminates the need for a luffing hoist winch (and associated ropes), speeding up and simplifying assembly and easing maintenance requirements.
The scale of the advantage is apparent on day one, where installation of a crane with VVH technology can take less than six hours, rather than the day and a half typical of traditional models that must reeve luffing cables through their jib. The counter-jib and jib foot containing the hydraulic system form a single, factory-assembled package that is transportable in one HC 40 container and can be bolted straight to the mast. Dismantling time is also similarly reduced.
On the job
Once in operation, the MRH and MCH models benefit from the same fast luffing speeds as the best traditional models, with VVH technology able to move the jib from 0-88° in under two minutes and providing superb handling regardless of wind speed or direction.
High productivity is ensured by the load-sensing hydraulic circuit that enables pressure to be adjusted as and when needed, courtesy of a variable-displacement pump that provides up to 300 bar max pressure. For example, on the MRH 125 an 80 cm3 pump pushes 30 kW to the 3 m-long hydraulic cylinder to raise the jib; while on the MRH 175 a 140 cm3 pump transfer 45 kW to the cylinder.
Oil flow and pressure are regulated proportionally to the angular movement of the control switch, meaning the operator is always able to accurately obtain the desired speed of luffing, with gentle and progressive movements.
A further advantage of Potain hydraulic luffing jib cranes is the shorter counter-jib, which again comes courtesy of a design that eliminates the need for a luffing hoist winch. This frees up valuable space on today’s increasingly congested job sites. For example, on the MRH 175 out-of-service radius is just 10.2 m, regardless of jib length.
Despite its reduced maintenance requirements, the VVH concept also offers advantages in terms of reliability. The hydraulic cylinder incorporates ball joints at either end that protect it from breakage risks, while supporting deformations of the jib. With no disassembly or handling required, the cylinder’s service life is also maximized.
“We believe that hydraulic luffing topless cranes have a very strong future in our industry, and we’ve been pleased with the uptake since we launched our first model in 2018,” says Thibaut Le Besnerais, vice president, brand and product management, tower cranes at Manitowoc. “Moving to a new type of crane can worry some companies, but Potain customers have already seen the advantages these new cranes deliver and how they help them achieve a stronger return on investment on their projects.”