What is the reasoning behind WLL requirements?
Discussion in 'Flatbed Trucking Forum' started by Bdog, Jan 14, 2019.
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Why is it adequate? Because based on experience, empirical testing and/or modelling, it has been determined that it is sufficient securement so long as it is applied correctly.
The WLL is the safe limit within which a securement or lifting device can be used and reused. In the case of securement devices it is generally between 1/4 - 1/6 of the minimum breaking strength/load (MBS/L). In the case of lifting and hoisting devices it is generally 1/10 of the MBS. -
For me it's all piece of mind .PoleCrusher Thanks this. -
straight from the FMCSA handbook:
Performance Criteria
FMCSA has adopted new performance requirements concerning deceleration in the forward direction, and acceleration in the rearward and lateral directions, that cargo securement systems must withstand. Deceleration is the rate at which the speed of the vehicle decreases when the brakes are applied, and acceleration is the rate at which the speed of the vehicle increases in the lateral direction or sideways (while the vehicle is turning), or in the rearward direction (when the vehicle is being driven in reverse and makes contact with a loading dock). Acceleration and deceleration values are commonly reported as a proportion of the acceleration due to gravity (g). This acceleration is about 9.8 meters/second/second (32.2 feet/second/second), which means that the velocity of an object dropped from a high elevation increases by approximately 9.8 meters/second (32.2 feet/second) each second it falls. FMCSA requires that cargo securement systems be capable of withstanding the forces associated with following three deceleration/accelerations, applied separately:
- 0.8 g deceleration in the forward direction;
- 0.5 g acceleration in the rearward direction; and
- 0.5 g acceleration in a lateral direction.
Generally, motor carriers are not required to conduct testing of cargo securement systems to determine compliance with the performance requirements. The new rules explicitly state that cargo immobilized or secured in accordance with the general securement rules, or the commodity-specific rules, are considered to meet the performance criteria.
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Ive never officially hauled equipment on the open road... But I have hauled a few pieces of farm equipment short distances... I always prefered 1/2" Grade 70 chain over 3/8"... And lots of them!!!
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PoleCrusher Thanks this.
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I don't think forward facing chains at a ~45 help much in pulling down adding friction to prevent forward motion. I do have a physics degree and could calculate it out but I am too lazy.
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