Although Acrow props are small in size, they’ve had a huge impact on the construction industry worldwide.
Here we take a closer look at what Acrow props are; how they work; what they offer to the construction industry; and some of the things to consider in designing support systems using this type of prop.
The Acrow prop is a simple but innovative type of construction equipment that offers temporary and adjustable vertical load bearing support. Also known as an Acrow jack, shore prop or post shore, Acrow props are typically used for shoring during building repairs – for example to support beams, doors and window frames while alterations are made.
First conceived by Swiss-born inventor William de Vigier in 1935, the original Acrow prop was designed to replace custom wooden props and scaffolding with a more cost effective and flexible form of temporary construction support. Today Acrow props are considered to be an essential tool of the trade, found on construction sites around the world.
Acrow props come in various designs, but most consist of:
Two lengths of adjustable high strength telescopic steel tubing – including one inner tube with a welded top-plate and one outer tube with a welded base-plate;
And a pin mechanism that locks these tubes in place when the desired length is reached.
Removing a pin that locks the tubes in place allows gross adjustments to be made to the length, before replacing the pin to lock the tubes in place again. An external thread that wraps around the tubes used is then used to make finer adjustments.
Alternative Acrow prop designs replace the sliding sections of tube with two threaded pipes that screw into each other. And clamping or ratcheting systems can be used in place of the pin mechanism.
Versatility: Acrow props can be used to perform a multitude of temporary propping tasks, including supporting falsework.
Simplicity: For ease of application most Acrow props require a quick 3-step set-up, allowing for installation by just one person.
Flexiblity: Acrow prop’s dual adjustment system allows fine-tuning to be performed once the props are in place. Weighing as little as 13kg, Acrow props can easily be moved around a site and reconfigured as required.
Acrow props come in five sizes – ranging from size 0 which extends from approximately 1050mm to 1800mm, right up to size 4, which extends up to 4900mm.
The axial compression load limits of Acrow props range from 7kN right up to 42.5kN.
The maximum weight Acrow props can support is approximately 4,300kg.
How many props do you need to support your load?
The amount of props you will need – and their placement – will depend on a range of other factors, including:
The length and weight of the load you need to support
The rating of each prop
The angle at which each prop will be placed
Whether supporting scaffolding will be used to brace the props
The size of top plates and bottom plates
Whether strong boys, timber needles or support masonry will also be used.
The extension on each prop once in use (the safe working load of the prop decreases as the prop is extended).
Structural engineers can guide you through prop selection and designing suitable support mechanisms. For all your propping and structural support needs contact Coates' specialist Engineering and Temporary Works team. Or find your local branch.
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