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Erection of hoists and mast climbers
The mast
Working with hoists and mast climbers? Find out what you need to know about the mast.
Mast overhang and thickness
The maximum mast overhang (a) shown on the installation drawing below must not be exceeded.
The maximum tie distance (b) as shown on the installation drawing must not be exceeded. The tie distance is the distance from the connection to the mast of one tie to the next.
Diagram of a mast
As a guide, the following values of a and b are common:
| Mast type | a (maximum overhang) | b (maximum spacing |
|---|---|---|
| Triangle mast | 3 metres | 3 metres |
| 450mm square mast | 6 metres | 6 metres |
| 650mm square mast | 9 metres | 9 metes |
Bolted joints should always be tightened to the required torque as prescribed by the instruction manual.
Any damaged or corroded components should not be used.
The correct mast wall thickness must be used as shown on the installation drawings.
For total mast heights under 100m this is generally the standard wall thickness of between 4mm and 6mm.
Wall thicknesses can be as large as 11mm and may be required for high or special installations.
Mast wall thickness diagram
Mast wall thickness diagram
Installing the mast
Installing and removing mast sections can be done by:
- hand (with a jib mounted on the hoist car) or,
- via a secondary crane.
When erecting the mast, the slings should be attached to designated lifting points or as high as possible on the section to ensure maximum stability. Always refer to manufacturer’s erection instructions.
Install the mast bolts before removing the crane or jib.
Installing the mast bolts upside down is the industry standard. Install with the mastbolt head on the underside of the mast and the mast nut on top:
Install the mast bolt with the bolt head at the bottom and nut on top
Mast straightness
Always make sure before connection to building that the mast is plumbed vertically.
The table below shows the allowable deviation of vertical. Unless specified in the installation design drawings.
| Height (m) | ≤5 | ≤20 | ≤40 | ≤60 | 70-100 | 100-150 | 150-200 |
| Deviation (mm) | ≤5 | ≤20 | ≤40 | ≤60 | ≤70 | ≤90 | ≤110 |
Allowable deviation of vertical
Mast ties
Hoists must be tied back to an appropriate structure before use. This includes building slabs or structural steel. Hoists should never be tied to scaffold.
There are many different hoist ties available. Each manufacturer has their own specific design.
But all mast ties have a simple principle for their design. Their principle is to stop the mast moving sideways or twisting. This is normally achieved by using two legs that spread from the mast to the building with a third leg that provides cross bracing. These legs can be a single frame arrangement or individual components.
Connection to the mast: triangle mast
A triangle mast normally requires a T bracket to be installed across the mast. This creates a connection point at the rear of the mast and also further back. This is needed to stop the mast twisting.
Refer to manufacturers installation instructions.
Connection is normally using pipe clamps.
Whenever pipe clamps are used there must also be a secondary system to make sure the tie can't be disengaged even if the clamp comes loose. There are two main ways of doing this:
- Use a secondary clamp.
- Use a bolt through the pipe and end cap on the pipe.