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306
100
LB
100
LB
100
LB
100
LB
100
LB
100
LB
Maximum Working Load (MWL)
Maximum Working Load (M.W.L.) is the maximum
static and/or dynamic load at which the product
will still function without excessive friction,
distortion, wear or permanent deformation of
components. Above this load, bearing systems
may fail, moving parts may seize and stainless
steel or plastic components may begin to bend,
stretch or otherwise deform. Maximum working
loads should never exceed half of the breaking
load, and should never be exceeded in use.
Breaking Load (BL)
Breaking Load (B.L.) is the load at, or around
which, a major failure can be expected to occur
to some part of the product’s structure when
new. Plastic components may split, rivets may
give way, shackles may break, and other metallic
components may fracture. No product should be
used at more than half of the breaking load, so as
to provide a minimum safety factor of two (2).
Factor of Safety
An appropriate factor of safety should be applied to Breaking Load figures to suit each
application before choosing or specifying a particular product. For many industrial
and safety related applications, and for some yachting applications, a factor of safety
greater than two (2) should be used or may be required by law or other regulations. It
is the customer’s responsibility to ensure that an appropriate factor of safety is used,
and it should allow for safety implications, service life, fatigue (as may be caused by
wave action, wind stresses or repetitive cyclical loading), type of load, exposure to
ultraviolet light, corrosion and stress corrosion (such as in high humidity or chlorine
environments). Note that a ‘safe working load’ is not specified as this is dependent on
the factor of safety, which must be determined by the user relative to each application.
Useful Life
The useful life of any product is determined by the above factors and must be
assessed in each application, and thus no guarantee can be provided for product life,
load capacity or any other factor due to the variability in usage. In some jurisdictions
government regulations require the replacement of rigging components within certain
periods of time, usually every three to five years. You must ascertain whether any
such regulations affect you. While every precaution is taken in the product design and
manufacturing processes to minimize the effects of corrosion and stress corrosion,
there are also preventative as well as corrective treatments that can be carried out
after installation. Contact Ronstan for further assistance and advice.
DEFINITIONS & CUSTOMER CONSIDERATIONS
Typical Purchase Systems
1:1
4:1
2:1
5:1
3:1
6:1
Mechanical
advantage
Single
Fix de den
Fixed end
Moving end
Moving end
Fix de den
Fixed end
Moving end
Moving end
Fix de den
Fixed end
Moving end
Moving end
Double,
becket
Single
Double,
becket
Double
Single,
becket
Triple
Single,
becket
Triple
Double
Triple,
becket
Mechanical
advantage
100
LB
pull
25
LB
pull
50
LB
pull
20
LB
pull
33
LB
pull
17
LB
pull
