Friday, 4 January 2013

Applied Load Points, Vectors & Base Slip For UK Ladders

The Hunter Ladder utilising Applied Load Point (ALP) and a Standard Load Vector (SLV).
RESEARCH AND TESTING: In 2000 the HSE commissioned Loughborough University to undertake detailed research into portable ladders and how they are used and how they fail. The result of their research, published in 2004, is available on the HSE Website. Their research led them to identify four potential failure modes:
  • Base Slip
  • Loss of top contact
  • Top side slip
  • Flip

They also identified the Applied Load Point (ALP) and a Standard Load Vector (SLV – the direction in which load should be applied) and the actual loads required to simulate a ladder user approaching the point of “misuse”. They then produced a Workshop Test Procedure and a series of tests using the ALP and the SLV and the different loads needed to identify if a Device Augmented Ladder (DAL) passed these tests, in which case the ladder was deemed to be “effective”, and fit for use. For a ladder to be deemed “effective” it had to remain standing when subjected to all these tests. This is clearly defined in the WAHR 2005.

DEVELOPMENT: In order to better understand the Loughborough Workshop Test proposals Ladder Safety Devices constructed a nine metre high test rig (right) and carried out extensive empirical tests on various prototypes and was able to develop a system which does indeed prevent failure in all four of the modes identified by the Loughborough report and thus complies with the requirements of the HSE as detailed in the HSE Operational Circular OC200/30 (see paragraph 32-38) issued on 4/11/05.

The result of that development is the range of Hunter Ladders which is unique in being the only range of ladders which are manufactured to the high specification demanded by the British Standard BS EN131 and at the same time comply with the Health and Safety Executive’s equally demanding standards regarding stability, as defined in HSE OC200/30 (see paragraph 32-38).

LEVELLER: It is a requirement of the HSE that the rungs of all ladders must be levelled (i.e.horizontal) before the ladder can be used (See HSE Ladders Leaflet INDG402). Every Hunter Ladder is fitted with an integral leveller in both of its  stiles, each one capable of providing an adjustment of 125mm (5”) in increments of 3mm (1⁄8”). This will enable the ladder to be set up on a slope of 16 degrees – the steepest slope permitted by the HSE. Adjustment is achieved very quickly by positioning the ladder, removing one of the locking pins, allowing the ladder to level itself, replacing the pin in the nearest visible hole (which is never more than 1.5mm (1⁄16”) away) and turning the pin to lock it.

BASE SLIP: The adjustable leveller sections have moulded feet which are made of specially formulated rubber designed to provide a very high level of grip on any substrate giving a level of resistance to base slip which complies with the HSE requirements and far exceeds that provided by standard ladder feet.

RESISTANCE TO SIDE SLIP AND FLIP: Every Hunter Ladder has on each side a one metre long stabilising bar which is clamped on below the bottom rung and hinges down to the ground. A telescopic strut which is attached at each arms centre point has 30 possible locking positions in increments of 12mm, to cater for uneven ground. These arms provide excellent lateral stability and complete resistance to “flip”.

TOP SIDE SLIP: At the top of every Hunter Ladder is a pair of wheels which are clamped to the ladder stiles. The rubber used in the “tyres” is of a special formulation which provides excellent grip on any substrate and gives excellent resistance to Top Side Slip. These wheels are also invaluable when running a ladder up a wall.

The Hunter Ladder: The entire range of Hunter Ladders is the only range of ladders which are manufactured to the high specification demanded by the British Standard BS EN131 and are fully compliant with the Health and Safety Executive’s demanding stability standards HSE OC200/30 paragraphs 32- 38.

The Hunter Stanbilising System Retrofit: A similar degree of stability and safety can be added to your existing ladders by fitting the Hunter Stanbilising System. This kit consists of the same wheels that are fitted to all Hunter Ladders, the same stabilising arms but with a clamp for the top mounting instead of a bolted fixing, plus a pair of levellers which slide over the stile rather than being inside the stile. The degree of stability is the same as in all Hunter Ladders. The end product is equally user-friendly. Fitting requires no drilling. Two kits are available, one with wheels, arms and levellers and one with wheels, arms and feet fitted with slip resistant rubber. Only spanners are needed and these are supplied with every kit.

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