CEN/TS 13001-3-5:2010

SLOVENSKI STANDARD
01-oktober-2010
Dvigala (žerjavi) - Konstrukcija, splošno - 3-5. del: Mejna stanja in dokaz varnosti
za kovane kavlje
Cranes - General design - Part 3-5: Limit states and proof of competence of forged
hooks
Krane - Konstruktion allgemein - Teil 3-5: Grenzzustände und Sicherheitshinweise von
geschmiedeten Haken
Appareils à levage à charge suspendue - Conception générale - Partie 3-5: Etats limites
et vérification d'aptitude des crochets forgés
Ta slovenski standard je istoveten z: CEN/TS 13001-3-5:2010
ICS:
53.020.20 Dvigala Cranes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL SPECIFICATION
CEN/TS 13001-3-5
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
January 2010
ICS 53.020.20; 53.020.30
English Version
Cranes - General design - Part 3-5: Limit states and proof of
competence of forged hooks
Appareils à levage à charge suspendue - Conception Krane - Konstruktion allgemein - Teil 3-5: Grenzzustände
générale - Partie 3-5: Etats limites et vérification d'aptitude und Sicherheitshinweise von geschmiedeten Haken
des crochets forgés
This Technical Specification (CEN/TS) was approved by CEN on 31 August 2009 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)
until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 13001-3-5:2010: E
worldwide for CEN national Members.

Contents page
Foreword .5
Introduction .6
1 Scope .7
2 Normative references .7
3 Terms and definitions, symbols and abbreviations .8
3.1 Terms and definitions .8
3.2 Symbols and abbreviations .9
4 General requirements . 11
4.1 Materials . 11
4.2 Workmanship . 12
4.3 Manufacturing tolerances . 13
4.4 Heat treatment . 13
4.5 Proof loading . 13
4.6 Hook body geometry . 13
4.7 Hook shank machining . 15
4.8 Nut . 15
4.9 Hook suspension . 16
5 Static strength . 16
5.1 General . 16
5.2 Vertical design load . 16
5.3 Horizontal design force . 17
5.4 Bending moment of the shank . 18
5.4.1 General . 18
5.4.2 Bending moment due to horizontal force . 18
5.4.3 Bending moment due to inclination of hook suspension . 18
5.4.4 Bending moment due to eccentricity of vertical force . 20
5.4.5 Special case for a ramshorn hook . 20
5.4.6 Design bending moment of the shank . 21
5.5 Hook body, design stresses . 21
5.5.1 Loadings . 21
5.5.2 Stress calculation methods . 22
5.5.3 Design stresses . 22
5.6 Hook shank, design stresses . 23
5.7 Hook, proof of static strength . 24
5.7.1 General for hook body and shank. 24
5.7.2 The use of static limit design force for verification of the hook body . 24
6 Fatigue strength . 25
6.1 General . 25
6.2 Vertical fatigue design force . 25
6.3 Horizontal fatigue design force . 25
6.4 Fatigue design bending moment of shank . 26
6.4.1 Bending moment due to horizontal force . 26
6.4.2 Bending moment due to inclination of hook suspension . 26
6.4.3 Bending moment due to eccentricity of vertical force . 26
6.5 Proof of fatigue strength, hook body. 27
6.5.1 Design stress calculation . 27
6.5.2 Stress history in general . 27
6.5.3 Stress history based upon classified duty . 28
6.5.4 Limit fatigue design stress . 29
6.5.5 Execution of the proof . 30
6.5.6 The use of fatigue limit design force for verification of the hook body . 31
6.6 Proof of fatigue strength, hook shank . 31
6.6.1 General . 31
6.6.2 Design stress calculation . 32
6.6.3 Applied stress cycles . 32
6.6.4 Basic fatigue strength of material . 33
6.6.5 Stress concentration effects from geometry . 33
6.6.6 Fatigue strength of notched shank . 34
6.6.7 Mean stress influence . 35
6.6.8 Transformation of stresses to a constant mean stress . 36
6.6.9 Stress history parameter in general . 36
6.6.10 Stress history parameter based upon classified duty . 37
6.6.11 Execution of the proof . 38
6.7 Fatigue design of hook shanks for serially produced hooks . 38
7 Verification of conformity with the requirements . 39
7.1 General . 39
7.2 Verification of manufacture . 39
7.3 Test loading . 39
7.4 Test sampling . 40
8 Information for use . 40
8.1 Maintenance and inspection . 40
8.2 Marking . 41
8.3 Safe use . 41
Annex A (informative) Sets of single hooks . 43
A.1 A series of single hooks of type RS/RSN, dimensions of forgings . 43
A.2 A series of single hooks of type RF/RFN, dimensions of forgings . 45
A.3 A series of single hooks of type B, dimensions of forgings. 47
Annex B (informative) A series of ramshorn hooks of type RS/RSN and RF/RFN, dimensions of
forgings . 49
Annex C (normative) Static limit design forces of hook bodies . 51
C.1 Static limit design forces of hook bodies for hooks of type RS and RF . 51
C.2 Static limit design forces of hook bodies for a series of hooks of type B, with additional
materials . 52
Annex D (normative) Fatigue limit design forces of hook bodies . 53
D.1 Fatigue limit design forces of hook bodies for hooks of type RS and RF . 53
D.2 Fatigue limit design forces of hook bodies for a series of hooks of type B, with additional
materials . 54
Annex E (normative) Hook body calculation and specific spectrum ratio factors . 55
E.1 Conversion factor for hook body calculation, when classified duty is utilized . 55
E.2 Specific spectrum ratio factors . 56
E.3 Underlying spectra for the specific spectrum ratio factors . 57
Annex F (normative) A selection of material qualities for hooks of type RS and RF . 60
Annex G (informative) Sets of hook shank and thread designs . 61
G.1 A series of hook shank and thread designs, a knuckle thread . 61
G.2 A series of hook shank and thread designs, a metric thread . 63
G.3 A series of hook shank and thread designs, a modified metric thread . 65
G.4 Hook shank and thread designs for hooks of type B . 67
Annex H (normative) Bending of curved beams . 69
Annex I (normative) Calculation of hook suspension tilting resistance, articulation by a hinge or a
rope reeving system . 72
Annex J (informative) Guidance for the selection of a hook size using the Annexes C to E . 76
Annex K (normative) Information to be provided by the hook manufacturer . 78
Annex L (informative) Selection of a suitable set of crane standards for a given application . 79
Bibliography . 80

Foreword
This document (CEN/TS 13001-3-5:2010) has been prepared by Technical Committee CEN/TC 147 “Cranes -
Safety”, the secretariat of which is held by BSI.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This Technical Specification is one part of the EN 13001 series. The other parts are as follows:
 Part 1: General principles and requirements
 Part 2: Load effects
 Part 3-1: Limit states and proof of competence of steel structures
 Part 3-2: Limit states and proof of competence of wire ropes in reeving systems
 Part 3-3: Limit states and proof of competence of wheel/rail contacts
According to the CEN/CENELEC International Regulations, the national standards organizations of the
following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia,
Slovenia, Spain, Sweden, Switzerland and the United Kingdom.

Introduction
This Technical Specification has been prepared to provide a means for the mechanical design and theoretical
verification of cranes to conform with essential health and safety requirements. This specification also
establishes interfaces between the user (purchaser) and the designer, as well as between the designer and
the component manufacturer, in order to form a basis for selecting cranes and components.
This Technical Specification is a type C standard.
The machinery concerned and the extent to which hazards are covered are indicated in the scope of this
standard.
1 Scope
This Technical Specification should be used together with the other relevant parts of the standard series. As
such, they specify general conditions, requirements and methods to prevent hazards in hooks as part of all
types of cranes.
This Technical Specification covers the following parts of hooks and types of hooks:
 bodies of any type of point hooks made of steel forgings;
 machined shanks of hooks with a thread/nut suspension.
NOTE 1 Principles of this Technical Specification can be applied to other types of shank hooks and also where stress
concentration factors relevant to that shank construction are determined and used. Plate hooks, which are those,
assembled of one or several parallel parts of rolled steel plates are not covered in this Technical Specification.
This Technical Specification is applicable to hooks from materials with ultimate strength of no more than
2 2
800 N/mm and yield stress of no more than 600 N/mm .
The following is a list of significant hazardous situations and hazardous events that could result in risks to
persons during normal use and foreseeable misuse. Clauses 4 to 8 of this document are necessary to reduce
or eliminate the risks associated with the following hazards:
a) Exceeding the limits of strength (yield, ultimate, fatigue);
b) Exceeding temperature limits of material;
c) Unintentional disengagement of the load from the hook.
The requirements of this Technical Specification are stated in the main body of the document and are
applicable to hook designs in general. The hook body and shank designs listed in Annexes A, B and G are
only examples and should not be referred to as requirements of this Technical Specification.
This Technical Specification is applicable to cranes, which are manufactured after the date of approval of this
standard by CEN, and serves as a reference base for product standards of particular crane types.
NOTE 2 This CEN/TS 13001-3-5 deals only with the limit state method in accordance with EN 13001-1.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 10002-1, Metallic materials ― Tensile testing ― Part 1: Method of test at ambient temperature
EN 10045-1, Metallic materials ― Charpy impact test ― Part 1: Test method
EN 10025-3:2004, Hot rolled products of structural steels ― Part 3: Technical delivery conditions for
normalized/normalized rolled weldable fine grain structural steels
EN 10222-4:1998, Steel forgings for pressure purposes ― Part 4: Weldable fine grain steels with high proof
strength
EN 10228-3:1998, Non-destructive testing of steel forgings ― Part 3: Ultrasonic testing of ferritic or
martensitic steel forgings
EN 10243-1:1999, Steel die forgings ― Tolerances on dimensions ― Part 1: Drop and vertical press forgings
EN 10250-2:1999, Open die steel forgings for general engineering purposes ― Part 2: Non-alloy quality and
special steels
EN 10250-3:1999, Open die steel forgings for general engineering purposes ― Part 3: Alloy special steels
EN 10254, Steel closed die forgings ― General technical delivery conditions
EN 13001-1:2004, Cranes - General design ― Part 1: General principles and requirements
EN 13001-2, Crane safety ― General design ― Part 2: Load effects
CEN/TS 13001-3-2, Cranes ― General design ― Part 3-2: Limit states and proof of competence of wire ropes
in reeving systems
EN ISO 4287:1998, Geometrical product specifications (GPS) ― Surface texture: Profile method ― Terms,
definitions and surface texture parameters (ISO 4287:1997)
EN ISO 12100-1:2003, Safety of machinery ― Basic concepts, general principles for design ― Part 1: Basic
terminology, methodology (ISO 12100-1:2003)
ISO 965-1:1998, ISO general purpose metric screw threads ― Tolerances ― Part 1: Principles and basic data
ISO 4306-1:2007, Cranes ― Vocabulary ― Part 1: General
3 Terms and definitions, symbols and abbreviations
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in EN ISO 12100-1:2003 and
ISO 4306-1:2007 and the following apply.
3.1.1
hook shank
upper part of the hook, from which the hook is suspended to the hoist media of the crane
3.1.2
hook body
lower, curved part of the hook below the shank
3.1.3
hook seat
bottom part of the hook body, where the load lifting attachment is resting
3.1.4
hook suspension articulation
feature of the hook suspension, allowing the hook to tilt along the inclined load line
3.1.5
serially produced hook
hook which is designed, manufactured and released to the market as a stand alone component or as part of a
hook block, without connection to a specific crane or application
3.2 Symbols and abbreviations
Table 1 — Symbols and abbreviations
Symbols, Description
abbreviations
Cross section area of the forged, shank
A
d1
A Cross section area of the critical section of hook shank
d4
A Minimum impact toughness of material
v
Acceleration
a
Seat circle diameter
a
a Throat opening
a Height of the hook point
Maximum width in the critical hook body section
b
max
Reference width
b
ref
C Total number of working cycles during the design life of crane
C Relative tilting resistance of the hook suspension
t
Coefficient for load eccentricity
c
e
Cumulative damage in fatigue (Palmgren-Miner hypothesis)
D
d Diameter of the forged shank
d Principal diameter of thread
Diameter of the undercut section of the shank
d
Thread core diameter
d
e Distance of the vertical load line from the centre line of the shank
R
F Vertical force
Vertical force on hook due to occasional or exceptional loads
F
H
Limit design forces, static / fatigue
F , F
Rd,s Rd,f
F Vertical design force for the proof of static strength
Sd,s
F Vertical design force for the proof of fatigue strength
Sd,f
Factors of further influences
f f , f
1, 2 3
Limit design stress
f
Rd
f Yield stress
y
f Ultimate strength
u
Acceleration due to gravity, g = 9,81 m/s
g
Horizontal design force of hook
H
Sd,s
H Horizontal design force for the proof of fatigue strength
Sd,f
h , h Section heights of the hook body
1 2
Vertical distance from the seat bottom of the hook body to the centre of the
h
articulation
h Vertical distance from the seat bottom of the hook body to critical section of hook
s
shank
i Index for a lifting cycle or a stress cycle
I Reference moment of inertia for curved beam
I Moment of inertia of the forged shank
d1
Moment of inertia of the critical section of hook shank
I
d4
k Conversion factor for stress spectrum and classified duty
C
k ,k Stress spectrum factors
h s
Table 1 (continued)
Load spectrum factor, in accordance with EN 13001-1
kQ
k * , k * Specific spectrum ratio factors, m = 5 / 6
5 6
lg Log to the base of 10
Bending moments of hook shank
M , M , M , M
1 2 3 4
Bending moments of hook shank for the proof of fatigue strength, lifting cycle i
M , M , M
1,f,i 2,f,i 3,f,i
M Static design bending moment
Sd,s
m Slope parameter of the characteristic fatigue design curve
Mass of rated hoist load
m
RC
Mass of the hook load in a lifting cycle i
m
i
N Total number of stress cycles / lifting cycles
N Reference number of stress cycles, ND =2 × 10
D
Pitch of thread
p
Average number of accelerations related to one lifting cycle
p
a
R Radius of hook body curvature
R Average depth of surface profile according to EN ISO 4287:1998
a
Maximum depth of surface profile according to EN ISO 4287:1998
R
z
Relief radius of the undercut
r
r Thread bottom radius
th
s Length of undercut
Stress history parameters
s , s
h s
Load history parameter
s
Q
t Depth of thread
T Operation temperature
Depths of notches
u , u
S T
Angle
α
Stress concentration factors
α , α
S T
Angle or direction of hook inclination
β
Notch effect factors
β ,β , β
n���nS nT
Dynamic factor for hoisting an unrestrained grounded load
φ
Dynamic factor for changes of acceleration of a movement
φ
Risk coefficient
γ
n
Partial safety factor
γ
p
General resistance coefficient
γ
m
Specific resistance coefficient
γ
sm
Fatigue strength specific resistance factors
γ ,γ
Hf Sf
Edge distance of a hook body section
η
Factor for load component
ν
Relative numbers of stress cycles
νh ,νs
Factor for mean stress influence
µ
Shank stress due to axial force
σ
a
Shank stress due to bending moment
σ
b
Mean stress in a stress cycle
σ
m
Stress amplitude in a stress cycle
σ
A
Design stress
σ
Sd
Table 1 (continued)
Basic fatigue strength amplitude, un-notched piece
σ
M
Total stress range in a pulsating stress cycle
σ
p
Fatigue strength amplitude, notched piece
σ
W
Transformed stress amplitudes
σ , σ , σ
Tmax T1 T2
Characteristic fatigue strength
∆σ
c
Limit fatigue design stress
∆σ
Rd
Stress range in a lifting cycle i
∆σ
Sd,i
Maximum stress range
∆σ
Sd,max
4 General requirements
4.1 Materials
The hook material in the finished product shall have sufficient ductility to permanently deform before losing the
ability to carry the load, at the temperatures specified for the use of the hook. Hook material, after forging and
heat treatment, shall have minimum Charpy-V impact toughness in accordance with Table 2.
Table 2 — Impact test requirement for hook material
Operation temperature Impact test temperature Minimum impact
toughness A
v
T ≥ - 30 °C - 20 °C
- 30 °C > T ≥ - 40 °C - 30 °C
27 J
- 40 °C > T ≥ - 50 °C - 40 °C
European standards specify materials and their properties. This standard gives a preferred selection. For
forged hooks, the material grades and qualities in accordance with Table 3 should be used. For more detailed
information see the specific European Standard.
Table 3 — Preferred materials for forged hooks
Material Selected qualities
standard
EN 10025-3 S275N S420N
S355N
EN 10222-4 P285NH P420NH
P285QH P420QH
P355NH
P355QH
EN 10250-2 S235J2
S355J2
EN 10250-3 25CrMo4+QT 34CrNiMo6+QT
34CrMo4+QT 30CrNiMo8+QT
36CrNiMo4+QT
Grades and qualities other than those mentioned in the above standards and in Table 3 may be used, if the
mechanical properties and the chemical composition are guaranteed by the manufacturer and conform to the
qualities of the standards referenced in Table 3.
The mechanical properties (yield stress, ultimate strength) are dependent upon the thickness of the forged
hook body. As a ruling thickness, either the largest width of the hook seat or the diameter of the shank shall
be used, whichever is greater.
For standardisation purposes, a classification of material grades for forged hooks is specified in Table 4. In
cases where the hook material is specified through the class reference, the values of mechanical properties
given in Table 4 shall be used as design values and shall be guaranteed as minimum values by the hook
manufacturer.
Table 4 — Material properties for classified material grades
Material Mechanical properties
class
reference
Yield stress Ultimate strength
f f
y u
N/mm² N/mm²
M 215 340
P 315 490
S 380 540
T 500 700
V 600 800
A selection of material qualities conforming to classes of Table 4 for hook sizes in accordance with Annexes A
and B is given in Annex F. Another selection of material qualities may be used, as long as the requirements of
Table 4 are met and guaranteed by the hook manufacturer.
4.2 Workmanship
The manufacturing process, factory tests and delivery conditions shall meet the requirements of EN 10254.
Each hook body shall be forged hot in one piece. The macroscopic flow lines of the forging shall follow the
body outline of the hook. Excess metal from the forging operation shall be removed cleanly leaving the
surface free from sharp edges.
Profile cutting from a plate is not permissible for forged hooks.
The surface roughness of the hook seat in the finished product shall be equal to or better than R 500 µm.
z
Grinding may be used to reach the required surface quality. Any grinding marks shall be in a circumferential
direction in respect to the seat circle.
After heat treatment, furnace scale shall be removed and the hook body shall be free from harmful defects,
including cracks. Hook forging shall be inspected for defects using appropriate NDT-methods according to
EN 10228-3. Requirements of quality class 1 of EN 10228-3:1998 shall be met.
No welding shall be carried out at any stage of manufacture.
4.3 Manufacturing tolerances
The dimensional tolerances according to EN 10243-1 for forging grade F shall be fulfilled, except as modified
herein.
The seat circle diameter and the throat opening shall be within [0 ; + 7 %] of the nominal dimension. The point
height dimension a shall be within [- 7 % ; + 7 %] of the nominal dimension.
The centre line of the machined shank shall not deviate from the seat centre more than ± 0,02 a .
The shape of the hook in its own plane shall be such that the centres of the material sections specified by the
two flanks of a section shall fall between two parallel planes with a spacing of 0,05 d .
4.4 Heat treatment
Each forged hook shall either be hardened from a temperature above the AC point and tempered, or
normalized from a temperature above the AC point. The tempering temperature shall be at least 475 °C.
The normalizing or tempering conditions shall be at least as effective as a temperature of 475 °C maintained
for a period of 1 h.
4.5 Proof loading
As part of the manufacturing process, a hook may be proof loaded. This initial proof loading can further assist
the Quality Assurance Management process as well as improve the fatigue performance of the hook in
general. If proof loading is applied, the process of proof loading shall be as follows:
a) Proof loading is applied after forging, subsequent to heat treatment and shank machining;
b) The proof load force shall be applied between the hook seat and the shank suspension nut, either as a
straight pull parallel to the hook shank or the load applied as in test loading in accordance with Figure 7;
c) A relative permanent set due to proof loading measured at the gap opening shall not exceed 0,25 %;
d) For batch-produced hooks the proof loading shall be applied to each hook in the batch;
e) Magnitude of proof load shall be such that the stress in the intrados exceeds the yield stress of the
material;
f) In general, the magnitude of proof load should be related to the static limit design force of the hook body
and be within limits between 1,0 × F and 1,2 × F ;
Rd,s Rd,s
g) After proof loading, the hook shall be inspected for defects using appropriate NDT-methods and found
free from harmful flaws, defects and cracks;
h) Proof loaded hook shall be stamped with symbol "PL" adjacent to the hook type marking.
NOTE Benefits derived from the application of the proof loading in subsequent fatigue performance and to the QA
Management process are not addressed within this standard.
4.6 Hook body geometry
Proportions of hook sections shall be such that stresses do not exceed stresses in the critical sections
specified in 5.5.1.
The seat of a hook shall be of circular shape. In a single hook, the centre of curvature shall coincide with the
centreline of the machined shank. In a ramshorn hook, the seat circle shall be tangential in respect to the
outer edge of the forged shank.
A ramshorn hook shall be symmetrical in respect to the centre line of the shank.

Figure 1 ― Hook dimensions
The diameter of the forged shank (d ) shall be proportioned to circle diameter (a ) as follows: d ≥ 0,55 a .
1 1 1 1
The bifurcation point between the inner edge and the seat circle (a ) shall be from the horizontal in minimum
as follows: for a single hook α ≥ 60°, for a ramshorn hook α ≥ 90°
The full throat opening (a ), without consideration to a latch shall be proportioned to the seat circle diameter
as follows: a ≤ 0,85 a . The effective throat opening with a latch shall be in minimum a ≥ 0,7 a .
2 1 o 1
The point height of a hook (a ) shall be in minimum as follows: a ≥ a .
3 3 1
Annexes A and B present example sets of hook body dimensions, which fulfil the requirements of this clause.
4.7 Hook shank machining
Figure 2 ― Machined dimensions of shank
The length of the threaded portion of the shank shall be not less than 0,8 d .
The pitch of the thread (p) shall be proportioned to the principal diameter of the thread (d ) as follows:
0,055 d ≤ p ≤ 0,15 d .
3 3
The depth of the thread (t) shall be proportioned to the pitch of the thread (p) as follows: 0,45 p ≤ t ≤ 0,61 p.
The bottom radius of the thread profile (r ) shall be no less than 0,14 p. A thread type, where the bottom
th
radius is not specified, shall not be used.
The shank shall be undercut (with a diameter d ) below the last threads for a length (s) proportioned to the
undercut depth as follows: s ≥ 2 (d - d ). The undercut shall reach deeper than the core diameter of the
3 4
thread profile (d ), in minimum as follows: d ≤ (d - 0,3 mm). The undercut shall be machined with a form
5 4 5
ground tool to a surface finish of R ≤ 3,2 µm and shall be free from machining marks and defects.
a
There shall be a relief radius in a transition from the threaded part to the undercut part. The relief radius (r )
shall be proportioned to the diameter of the undercut (d ) as follows: r ≥ 0,06 d . The shape of the relief
4 9 4
transition need not be a complete quadrant of a circle.
The thinnest section of the machined shank (consequently d ) shall fulfil the condition d ≥ 0,65 d , where d is
4 4 1 1
the diameter of the forged part of the shank, see Figure 1
The whole machined section of the shank shall have a radius at each change in diameter. The machined
section shall not reach the curved part of the forged body.
Screwed threads shall comply with the tolerance requirements of ISO 965-1 (coarse series) and be of medium
fit class 6g.
Annex G presents example sets of machined shank and thread dimensions, which fulfil the geometric
requirements.
4.8 Nut
The material grade of the nut shall be equal to that of the hook
The height of the nut shall be such that the threaded length of the hook shank is fully engaged with the nut
thread.
The nut shall be positively locked to the shank against rotation to prevent the nut from unscrewing. The
locking shall not interfere with the lower two thirds of the nut/shank thread connection. The locking shall allow
relative axial movement between the shank and the nut due to play in the threaded connection. Alternatively, if
the nut is locked by a dowel or other similar fixing media, it is essential during the locking process that the
nut/shank load bearing thread flanks are in direct contact to ensure resultant unimpaired load transmission.
The nut shall rest on an anti-friction bearing, enabling the hook body to rotate about the vertical axis. The
contact surface of the nut resting on the bearing shall meet the requirements as stipulated by the related
bearing. The height position of the contact surface shall fall within the lower half of the thread connection.
Screwed threads of the nut shall comply with the tolerance requirements of ISO 965-1 (coarse series) and be
of medium fit class 6H. The bottom radius of the thread profile for the nut shall be not less than 0,07 p, where
p is the pitch of the thread. A thread type, where the bottom radius is not specified, shall not be used.
4.9 Hook suspension
In general, and always for serially produced hook blocks, the hook suspension together with hoist rope
reeving system shall be such that the system allows free tilting of the hook in any inclined direction of the load
line. In cases where this articulation of the hook suspension is not provided, this shall be specially taken into
consideration in the design calculations of the hook. In cases, where by changing the crane/hook block
configuration or position the hook suspension can be brought to a rigid position, this shall be taken into
account in the design calculation of the hook.
The same load actions as specified for the hook shall be taken into account in the design of the hook
suspension.
5 Static strength
5.1 General
The proof of static strength for hooks shall be carried out in accordance with principles of EN13001-1 and
EN13001-2. The general design limit for static strength is yielding of the material.
The proof shall be delivered for the specified critical sections of the hook, taking into account the most
unfavourable load effects from the load combinations A, B or C in accordance with EN 13001-2. The relevant
partial safety factors γ shall be applied. The risk coefficients γ shall be applied when required in the specific
p n
application or as specified in the relevant European crane type standard.
5.2 Vertical design load
The vertical design force for a hook F when hoisting the rated hook load, shall be calculated as follows:
Sd,s
F = φ × m × g × γ × γ (1)
Sd,s RC p n
 
 
 a 
with φ = max φ ;1 + φ × 
 2 5 
 
 g 
 
 
where
φ is the dynamic factor, when hoisting an unrestrained grounded load, see EN 13001-2;
φ is the dynamic factor for loads caused by hoist acceleration, see EN 13001-2;
a  is the vertical acceleration or deceleration;
m is the mass of the rated hook load;
RC
g  is the acceleration due to gravity, g = 9,81 m/s ;
γ  is the partial safety factor, see EN13001-2;
p
γ = 1,34 for regular loads (load combinations A);
p
γ = 1,22 for occasional loads (load combinations B);
p
γ = 1,10 for exceptional loads (load combinations C);
p
γ  is the risk coefficient.
n
Other load actions and combinations of EN13001-2 may produce vertical forces on the hook, whose load
actions shall also be analysed. The vertical design force in such cases is expressed in a general format as
follows:
F = F × γ × γ (2)
Sd,s H p n
where
F is a vertical force on hook due to other load action than hoisting a rated load; e.g. a test load or a
H
peak load in an overload condition;
γ is the partial safety factor as above, see EN13001-2;
p
γ is the risk coefficient.
n
5.3 Horizontal design force
The horizontal forces that are most significant for the strength of hooks are those caused by horizontal
accelerations of the crane motions. Other horizontal forces e.g. due to wind or sideways pull actions shall be
taken into account, if significant. The horizontal force shall be assumed to act at the bottom of the hook seat.
The horizontal design force of hook H due to horizontal accelerations shall be calculated as follows:
Sd,s
m × a ×φ ×γ ×γ 
RC 5 p n
 
H =min (3)
 
Sd,s
C × F h
 
t Sd,s
 
where
m is the mass of the rated hook load;
RC
a is the acceleration or deceleration of a horizontal motion;
φ is the dynamic factor for loads caused by horizontal acceleration, see EN 13001-2. For hook
suspensions, which are not rigidly connected in horizontal direction to the moving part of the crane, it
shall be set φ = 1;
γ is the partial safety factor as for Equation (1);
p
γ is the risk coefficient;
n
C is the relative tilting resistance of the hook suspension in accordance with Annex I;
t
F is the vertical design force in accordance with 5.2,
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