Lifting Sling/Strap Material
The lifting Slings we intend to use are made out of a
material called high tenacity polyester yarn which is renowned for its
hardwearing properties. Widely used through out industry and construction due
to their low weight, flexibility and ease of use. These lifting slings are also
relatively cheap with an example of lifting capabilities and prices from lift
safe solutions below;
For our Gantry crane, it is recommended that we supply our
product with straps capable of lifting 2 tonne to ensure durability through use
and be at least 6m in total length to ensure it can deal with awkward loads.
Source: www.liftsafesolutions.co.uk
Bow Shackle Material
When deciding which material would be best suited to use for
our bow shackles, it came down to two options, high tensile or stainless steel.
High Tensile steel would offer us extreme durability and strength at a
relatively low cost; however from our design specification, it is clear that
the crane will be used in disaster areas, it is therefore accepted that the
crane must be durable in all weather conditions. This therefore lead us to turn
to using stainless steel Bow Shackles, which still offer great strength yet
also offer good corrosive resistance. An example of the load capacity and price
for an ideal Bow shackle can be seen below.
Source: www.s3i.co.uk
D ring limits to fail before 1.2 tonnes to prevent damage
to crane.
With our D-rings also being manufactured from stainless
steel it is accepted that it is more likely that the crane will fail before any
of the lifting gear. As a result of this it has been seen as a good idea to
implement a safety device within the design to ensure the protection of the
main crane assembly, this will ensure longer product life and serviceability,
key for our design success. To this end, we have proposed that all our D-rings,
which connect the load to the pulley system be designed to fail when it is
loaded with more than 1.2 tonnes, a safe loading limit with enough leeway
either side of 1 tonne to ensure safe operation of the crane.
