Hand operated manual chain hoists (also commonly
known as a chain block or block and tackle) are a piece
of portable lifting equipment available in versatile
configurations; they are very adaptable to the many
alterative working scenarios and working environments
including permanent and temporary installations.
Mechanical strength
o The mechanical strength shall be checked by an
appropriate calculation method. Hand chain block have a
coefficient of utilization of at least 4:1.
o Hand chain block shall be designed to withstand 1500
cycles with 110% of the rated capacity with no failure or
replacement of parts, no resting time, except for
lubrication.
o A lifting path of the load chain of at least 300mm per
cycle in order to get at least a complete revolution of the
load chain wheel.
Hand chain blocks shall have an automatic braking
function during the lifting and lowering operation.
 The braking function shall be automatic when the
operating force ceases, whether the motion is lifting or
lowering.
 The braking device shall allow a regular descent under
operator control whatever the position of the load.
 The brake shall not contain asbestos.
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The fracture of a spring shall not lead to a failure of the braking
system except the springs used for load hook safety latches.
Guided pressure springs shall have a distance between the coils of
less than or equal to the wire diameter.
When using several springs in the case of the failure of one
spring, the remaining spring shall ensure that the retention is
maintained.
OPERATING ELEMENTS
Hand chains shall be secured against unintentional disconnection
from the hand chain wheel.
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To lift the rated capacity the operating effort of each operator shall
not exceed 55 daN on the hand chain.
To avoid over loading the operating effort of each operator to lift
the rated capacity shall be between the following values:
a) Rated capacity</- 1000kg : 20daN to 55dan on hand chain.
b) 1000 kg < rated capacity,5000 kg : 40daN to 55 daN.
c) 5000 kg </- rated capacity : 45 daN to 55 daN.
Accessible parts of the hand chain block shall have no
sharp edges, no sharp angles, and no rough surfaces
likely to cause injury.
 Gearing shall be guarded to prevent accidental ingress
of parts of the body.
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Hooks shall be fitted with safety latches to prevent unintentional
detachment.
The top hook shall be capable of swivelling for correct
positioning.
Load hooks used as lifting medium which are not manufactured in
accordance with a recognised standard shall not show permanent
deformation at a static load of 2-times the rated capacity.
At a static load of 4-times the rated capacity, the hook shall be
allowed to bend however the load shall remain held safely.
 Stripper
is a mechanical device which
separates the hand chain and the load chain.
 Chain
anchorage devices of the fixed end type
shall withstand 4 times the static chain tensile
force at rated capacity without rupture.
 The free end of the load chain shall be fitted with a
chain end stop to prevent it from passing through
completely.
 The end stop shall withstand without rupture 2.5
times the static chain tensile force at rated
capacity.
 Hand
chain blocks and their components shall be
capable of operating within an ambient
temperature range of -10◦c to +50◦c unless another
temperature range is agreed between the
manufacture and the purchaser.
 The
braking system and the overload protection
system shall only be able to be removed, modified
replaced interfered or neutralised by the use of
tools.
Safety Requirements
Design:
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Each hook shall have a spring loasded latch
conforming to ensure that the load cannot become
accidently unhooked.
The form of the upper end shall be either of the eye
type or the clevis type.
 The
actual point height shall be equal or greater
than the full throat opening.
 The full throat opening shall not exceed 95% of
the actual seat diameter.
 The hook latch shall be capable of closing over the
maximum diameter of bar, that can be admitted
through the actual throat opening.
TERMS & DEFINITION
 Nominal size(dn): Nominal diameter of the round
section steel wire or bar from which the chain is
made.
 Material dia: Diameter of the material in the
chain link as measured.
 Weld Diameter: Diameter at the weld as
measured (1.1xdn).
 Pitch: Internal length of a link as measured(3xdn).
Working load limit: Maximum mass which the chain
hanging vertically is authorized to sustain in general
lifting services.
 Total ultimate elongation: Total extension at the point
of fracture of the chain expressed as a percentage of the
internal length of the test sample(Max:3%).
 Weld Width: The width of the weld as
measured(0.6xdn).
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BS EN 13157:2004- CRANES SAFETYHAND POWERED LIFTINGEQUIPMENT
BS EN818-1:1996+A1:2008
BS EN 1677-2:2000+A1:2008