In our previous blog about replacing windows of high-rise structures, we described multiple ways to replace glass panels at great heights. This introduction to equipping Building Maintenance Units (BMUs) with a Glass Replacement Unit (GRU) focused on structures with a straight facade.
But structures are sometimes designed and built according to contemporary architectural trends. This means that facades aren’t always straight, but have an inclination angle, have twisting or protruding parts and other design elements that make some facade areas hard to reach.
To be able to replace glass panels at those areas, we have developed special equipment and tools.
Replacing glass panels with the help of a GRU balancer
Inclining facades
The tools that have to be used for replacing a glass panel at an inclining facade are the GRU pulley and the GRU pulley bar. These tools make sure that the snap-hook and the glass panel can be suspended close to the inclining facade.
How is a glass panel replaced at an inclining facade?
Replacing glass panels with the help of a GRU pulley bar
Step 1
The steel wire rope of the GRU (green) is attached to the GRU pulley that is going to be installed on the building, before the cradle descends. The glass hook is taken into the cradle and by using the soft rope system, the cradle stays close to the facade.
Step 2
The cradle descends until right above the level where the glass panel needs to be installed. There, a pulley bar and the GRU pulley are connected to the facade. The GRU wire runs along the pulley on the facade-side to keep the glass hook close to the facade. The cradle and glass hook descend to ground level where the glass panel will be attached.
Step 3
The cradle descends until the level of where the glass panel has to be installed. The glass hook, with the glass panel attached, is hoisted to that level.
Step 4
By tightening the soft rope system (red) the cradle moves closer to the facade and the workers are able to place the glass panel into position.
Replacing glass panels from the side or backside of the cradle
In some cases, the glass panel that has to be replaced is located at the side or backside of the cradle. In general, the glass hook is suspended in front of the cradle. Thus, a tool is needed to relocate the position of the glass hook. In this case, a temporary GRU guiding wheel is installed.
This guiding wheel is installed on the spreader, before the BMU comes operational. It will function as the last pulley of the GRU wire rope and therefore is able to extend or relocate the position where the glass hook will descend relative to the cradle, depending on how it’s mounted.
In some cases, the glass panel that has to be replaced is located at the side or backside of the cradle. In general, the glass hook is suspended in front of the cradle. Thus, a tool is needed to relocate the position of the glass hook. In this case, a temporary GRU guiding wheel is installed.
The Temporary guiding wheel
Situation 1
The glass hook at the end of the GRU is suspended in front of the cradle to replace glass panels. In general, this is the standard situation.
Situation 2
The temporary GRU guiding wheel is used to suspend the glass hook at the back of the cradle. This enables workers to replace glass panels on that side.
Glass replacement beneath protruding areas
A pantograph cradle is generally used to be able to access facade areas that are located beneath protruding structural elements. But, to be able to replace
windows there, a specific piece of equipment is needed: a GRU balancer.
This is a steel beam with a hook and/or suction tool (vacuum lifter) at one end and a movable counterweight on the other end to balance the system. The beam is attached to the glass hook of the GRU between the wire ropes of the cradle itself.
Because the suspension point of the balancer is in the middle, the beam reaches over the cradle and holds the glass panel in front of it (see photo).
The Temporary guiding wheel
How does a GRU balancer work?
In some situations, the GRU balancer is also used for inclining parts of the facade. In that case, an adjustable suction tool is attached to the GRU balancer. The angle of the suction tool can be manually adjusted to position the glass panel according to the angle of the facade, simplifying the installation.
Step 1
The GRU balancer and pantograph cradle descend to a lower level to attach the glass panel to the suction tool.
Step 2
The GU balancer and pantograph cradle ascend to the level where the glass needs to be replaced.
Step 3
The jib of the BMU withdraws or the roof car drives backwards to move both the GRU balancer and pantograph cradle towards the facade below the protruding area.
Mobile Glass Replacement Unit
Sometimes, the situation asks for a solution other than hoisting or lowering the glass panel with a BMU-mounted GRU. For these situations, we have developed a mobile GRU unit or Davit arm GRU. This is a small, movable unit with a winch and a jib that can hold a glass panel. It can be moved by using a pallet truck.
It is used on flat surfaces, like terraces, in combination with a monorail system, because a monorail system itself is not suitable for carrying heavy glass panels.
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