STABILITEIT PLATFORM TRAILERS
Trailer with load tipped over! Why did this happen?
Op het World Crane & Transport Summit (WC&TS) van 22-23 Oct. 2010 in Amsterdam heb ik een “Paper” gepresenteerd over onderstaand onderwerp. Dit is door de industrie goed ontvangen en zal door de “ESTA” en “SC&RA” worden opgevolgd.
Guidelines on trailer stability needed or not?
I realize, I may step on some sensitive toes by addressing the issue of trailer stability, but I feel it is time to put this forward to the industry and find out whether we can achieve improvement on safety in dealing with trailer stability and stop the tipping over of large loads.
The shipping Industry has certain rules related to ships stability and all floating vessels have to comply with these rules, otherwise they are not insured. I am refering to certain GM (arm of stability) values. Depending on the size, type and year of construction of the floating vessel, these GM values can vary. The lifting Industry has also set certain rules related to crane stability. Today all crane capacity charts should comply with a rated lifting capacity of 75% of tipping load, which boils down to a 33% marging on the load before a crane actually tips over. All cranes with a CE mark must comply with this rule and should be equipped with a good working load limiting and loadmoment indicator and other safety devices. The times that a crane operator operated his crane on the feeling of his butt should not exist anymore.These rules have only one goal, to protect the operator and equipment from accidents, such as tipping over and injury to people and damage of equipment. Safety is of great importance nowadays and everyone should do his best to ensure a safe working condition for operating personnel as well as for the envronment.It is therefore a bit awkward that transporting heavy loads is left to the transport contractor and that there are hardly any rules to ensure safety of the load and trailer.I therefore strongly encourage the Industry to establish stability rules. These rule at the stert can work as a guideline to be more refined in detail after input from the various transport contractors. I also realize these stability rules may have a commercial or even political effect. When rules are set, these should be adhered to nation- and or even worldwide otherwise it will not work. As a start I would recommend following very simple and basic safety rule: As a rule of thumb, in case the load is twice the diameter as the width on which the load is transported one should be aware of the fact that stability may become critical. In many cases this boils down to the fact that the theoretical tipping angle is around 10o. What is the theoretical tipping angle?
In order to understand this one should realize that a hydraulic platform trailer can be set to a four point or three point suspension system. The favoured suspension system is the so-called threepoint suspension system, as the load is then equally distributed over all tires in case the CoG of the load is symetrically placed between the suspension points. A better suspension system would be an a-symmetrical suspension system.
Another issue is the so-called hydraulic stability. It is a combination of the theoretical tipping angle as well as the hydraulic stability, which should avoid any overload in the trailers hydraulic suspension suspension system and decides what is safe and what is not. It is knowing where the centre of Gravity of the load is located in relation to the suspension points of the trailer. To develop a proper set of guidelines the details of stabilty should be outlined and made public for the Industry for review and finally agreement.
More is discussed and presented in the Mini-Seminar “Heavy Transport & Lifting”.
Join the next public two day Seminar in Perth on the 19th and 20st of March 2010 in West Australia.
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