Mast climbers have greatly increased the productivity of masonry contractors, especially those used in larger commercial or public buildings. One manufacturer (Fraco) did a time-and-cost study comparing conventional scaffolding to the firm's mast climber for a 105-foot-long by 40-foot-high wall; the results showed a savings of 162 hours (288 worker hours versus 450 worker hours) and $2600 (over 30%).
But mast climbers are not right for every job and every contractor. "It's a trade-off between the amount of time spent working from the mast climber and the amount of time spent positioning it and setting it up," states Jean Robillard of Bennu Innovations.
Masonry work in general is a perfect application for mast climbers because of all the materials and people that have to be positioned close to the wall. "A mast climber is most useful on a project that can be done in a single direction," says Chad Baumgartner, Avant-Garde Engineering. "The intention is to turn the work area into a vertical production line."
Alimak invented electric mast climbers in Europe in 1958, an offshoot of construction hoists. The hydraulic systems originated about 15 years ago as the brainchild of a group of masons in Quebec.
The characteristics of mast climbers that allow more productive construction are
- Large work spaces
- Ease of positioning workers and materials
- Very low maintenance requirements
- Effective safety features
Mast climbing work platforms can be configured for nearly any shape or size of building. The demands of a project determine whether the priority is to have very high platforms or very long platforms or to be able to quickly move horizontally. Most manufacturers will work with a contractor to help define what equipment is ideal for current and anticipated future projects.
The vertical truss structure that the platform climbs can be configured either as a twin mast or a single mast. The base unit includes a drive system-a rack-and-pinion-driven electric system or a hydraulic The big differences between the electrics and the hydraulics are the vertical speed and load capacity.
Pieces called bridges, cantilevers, or extensions are used to bridge base units or to cantilever off base units either to make the platform longer or to project at an angle.
Some manufacturers have steel platforms, which they say are safer and more stable, while others use plywood platforms. All units have outriggers that project toward the building face and are overlaid with scaffold planks. This so-called masons' platform is customized to follow the contour of the wall.
Masts with lower maximum capacity (lighter weight platform) can go higher without bracing. Beyond that, the mast must be tied back to the wall at about 20-foot intervals. With ties, mast climbers can rise as high as 550 feet.
To get materials efficiently onto the platform, a hoist is essential. Many accessories are available for most platforms.
Although a mast climbing work platform is an expensive piece of equipment, it will soon pay for itself. Fraco claims the cost can be recovered in 7 months, depending on how much the mast climber is used. Electric machines are considerably more expensive than hydraulic machines but their high speeds offer some real advantages.
The article also gives information on eight manufacturers of mast climbing work platforms.