prEN ISO 4254-19

SLOVENSKI STANDARD
01-junij-2026
Kmetijski stroji - Varnost - 19. del: Stroji za krmo in steljo za živino (ISO/DIS 4254-
19:2026)
Agricultural machinery - Safety - Part 19: Livestock feed and bedding machines (ISO/DIS
4254-19:2026)
Matériel agricole - Sécurité - Partie 19: Machines pour l'alimentation et la litière du bétail
(ISO/DIS 4254-19:2026)
Ta slovenski standard je istoveten z: prEN ISO 4254-19
ICS:
65.060.99 Drugi kmetijski stroji in Other agricultural machines
oprema and equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 4254-19.3
ISO/TC 23/SC 3
Agricultural machinery — Safety —
Secretariat: DIN
Part 19:
Voting begins on:
Livestock feed and bedding 2026-04-21
machines
Voting terminates on:
2026-06-16
ICS: 65.060.99
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
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Reference number
ISO/DIS 4254-19.3:2026(en)
DRAFT
ISO/DIS 4254-19.3:2026(en)
International
Standard
ISO/DIS 4254-19.3
ISO/TC 23/SC 3
Agricultural machinery — Safety —
Secretariat: DIN
Part 19:
Voting begins on:
Livestock feed and bedding
machines
Voting terminates on:
ICS: 65.060.99
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
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Published in Switzerland Reference number
ISO/DIS 4254-19.3:2026(en)
ii
ISO/DIS 4254-19.3:2026(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Safety requirements and/or protective risk reduction measures . 4
4.1 General .4
4.2 Controls .4
4.2.1 Controls located on the workstation or in the operator station .4
4.2.2 Remote controls .5
4.2.3 Emergency stop .5
4.2.4 Safety and reliability of control systems .5
4.3 Visibility of work areas of cutting, loading and cutting/loading devices .5
4.3.1 Operator’s eye position .5
4.3.2 For work area at front of the machine .5
4.3.3 For work area at rear of the machine .6
4.3.4 For work areas at sides of machine .6
4.4 Loading devices .9
4.4.1 General .9
4.4.2 Loading door .9
4.5 Cutting devices .10
4.5.1 General .10
4.5.2 Stopping time.10
4.5.3 Maintenance and repair .11
4.5.4 Blockages.11
4.6 Mixing/chopping device . 12
4.6.1 Guarding for a machine equipped with cutting, loading, or cutting/loading tools . 12
4.6.2 Guarding for a machine equipped with gravity discharge . 12
4.6.3 Guarding for a machine equipped with distribution device . 13
4.7 Mixing/chopping chamber .14
4.7.1 Viewing inside chamber.14
4.7.2 Reducing material build-up .14
4.7.3 Manual addition of material . 15
4.7.4 Maintenance and repair . 15
4.8 Moving floor . 15
4.9 Distribution device . 15
4.9.1 General . 15
4.9.2 Conveyors .16
4.9.3 Augers .17
4.9.4 Distributor cylinders .18
4.9.5 Impellers .19
4.10 Scale display. 22
4.11 Noise . 22
4.11.1 Reduction at source by design and by protective measures . 22
4.11.2 Verification of requirements on noise . 23
4.11.3 Reduction by information . 23
4.12 Stability and immobilization . 23
4.12.1 General . 23
4.12.2 Supporting devices . 23
4.12.3 Hitch loading . 23
4.13 Electro-magnetic compatibility (EMC) .24
5 Verification of the safety requirements and/or protective risk reduction measures .24
6 Information for use .25

iii
ISO/DIS 4254-19.3:2026(en)
6.1 Operator's manual . 25
6.1.1 General . 25
6.1.2 Preparing the machine. 25
6.1.3 Operating the machine . 25
6.1.4 Servicing and maintaining the machine . . 26
6.1.5 Noise .27
6.2 Marking .27
6.2.1 General .27
6.2.2 Safety signs .27
Annex A (informative) List of significant hazards .28
Annex B (informative) Examples of machines and components .31
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of Directive 2006/42/EC aimed to be covered .40
Bibliography .43

iv
ISO/DIS 4254-19.3:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent
rights identified during the development of the document will be in the Introduction and/or on the ISO list of
patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 23, Tractors and machinery for agriculture
and forestry, Subcommittee SC 3, Safety and comfort.
A list of all parts in the ISO 4254 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
ISO/DIS 4254-19.3:2026(en)
Introduction
This document is a type-C standard as stated in ISO 12100:2010.
This document is of relevance, in particular, for the following stakeholder groups representing the market
players with regard to machinery safety:
— machine manufacturers (small, medium and large enterprises);
— health and safety bodies (regulators, accident prevention organisations, market surveillance, etc.)
Others can be affected by the level of machinery safety achieved with the means of the document by the
above-mentioned stakeholder groups:
— machine users/employers (small, medium and large enterprises);
— machine users/employees (e.g. trade unions, organizations for people with special needs);
— service providers, e.g. for maintenance (small, medium and large enterprises);
— consumers (in case of machinery intended for use by consumers).
The above-mentioned stakeholder groups have been given the possibility to participate at the drafting
process of this document.
The machinery concerned and the extent to which hazards, hazardous situations or hazardous events are
covered are indicated in the Scope of this document.
When requirements of this type-C standard are different from those which are stated in type-A or type-B
standards, the requirements of this type-C standard take precedence over the requirements of the other
standards for machines that have been designed and built according to the requirements of this type-C
standard.
NOTE Examples of machine and components, illustrating the terms and definitions in Clause 3, are given in
Annex B.
vi
DRAFT International Standard ISO/DIS 4254-19.3:2026(en)
Agricultural machinery — Safety —
Part 19:
Livestock feed and bedding machines
1 Scope
This document, used together with ISO 4254-1, specifies the safety requirements and their verification for
the design and construction of livestock feed and bedding machines that can perform a combination of two
or more of the following processes: loading, mixing, chopping and distributing materials. In addition, it
specifies the type of information on safe working practices to be provided by the manufacturer.
NOTE Livestock feed and bedding machines (for example feed mixers, bale processors, silage block cutters) can
be stationary, mounted, semi-mounted, interchangeable towed or self-propelled.
Examples of machines and components covered by this document are shown in Annex B.
When requirements of this document are different from those which are stated in ISO 4254-1, the
requirements of this document take precedence over the requirements of ISO 4254-1 for machines that have
been designed and built according to the requirements of this document.
This document is not applicable to:
— machines which pick up or transport crop material directly from the field;
— loading cranes;
— automated, semi-autonomous and autonomous functions (for example, those covered by ISO 3991)
— the integrity of safety-related parts of control systems in relation to the specification of performance
levels;
— environmental hazards (excluding noise), road safety and hazards associated with moving transmission
parts;
— hazards associated with maintenance or repairs carried out by professional service personnel.
This document deals with the significant hazards, hazardous situations and events relevant to machines
for loading, mixing and/or chopping and distributing silage and/or other feedstuffs, when they are used as
intended and under the conditions foreseen by the manufacturer as listed in Annex A, except for the hazards
arising from:
— failure of the control circuit;
— inadequate seating;
— inadequate lighting;
— travelling of machinery related to road safety;
— break-up of parts rotating at high speed;
This document is not applicable to machines manufactured before the date of publication of this document.

ISO/DIS 4254-19.3:2026(en)
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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.
ISO 3600:2022, Tractors, machinery for agriculture and forestry, powered lawn and garden equipment —
Operator's manuals — Content and format
ISO 4254-1:2013, Agricultural machinery — Safety — Part 1: General requirements
ISO 5353:1995, Earth-moving machinery, and tractors and machinery for agriculture and forestry — Seat index
point
ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk reduction
ISO 13851:2019, Safety of machinery — Two-hand control devices — Principles for design and selection
ISO 13857:2019, Safety of machinery — Safety distances to prevent hazard zones being reached by upper and
lower limbs
ISO 15817:2012, Earth-moving machinery — Safety requirements for remote operator control systems
ISO 16001:2017, Earth-moving machinery — Object detection systems and visibility aids — Performance
requirements and tests
IEC 60204-1:2016, Safety of machinery - Electrical equipment of machines - Part 1: General requirements
3 Terms and definitions
For the purposes of this document, the following terms and definitions given in ISO 12100:2010,
ISO 4254-1:2013 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
Livestock feed and bedding machines

3.1.1
feed mixer
machine with a chamber and powered mixing/chopping device(s) for blending of feed stocks and
supplements, and a means for dispensing the blended material
Note 1 to entry: The mixing/chopping devices can consist of, but are not limited to, rotating augers, rotors (for example
paddles, ribbons, bars, knives), or a combination of augers and rotors.
3.1.2
bale processor
machine or device with an open-top chamber and powered chopping elements intended to chop baled
materials and distribute the processed material used for livestock feed or bedding
3.1.3
silage block cutter
device with cutting edge(s) that is used to cut a block of material from the remaining material and transport
the material for processing or distribution while maintaining the material density and form

ISO/DIS 4254-19.3:2026(en)
3.2
Processes
3.2.1
mixing
operation to blend two or more different materials to create a mixture
3.2.2
chopping
operation to break up or reduce the size of the constituent elements of a mass of material
3.2.3
cutting
operation to sever a portion of material from the remaining material
3.3
Loading device
element or set of elements attached to the machine where material is loaded into the machine
Note 1 to entry: Loading arms/forks on bale processors are not considered to be part of this definition.
3.3.1
loading door
moveable portion of the chamber that opens for loading of the machine and closes during the processing of
material
3.3.2
loading conveyor
powered mechanism that continually moves material into the chamber
3.4
cutting/loading device
element or set of elements attached to the machine that, alone or in combination, perform the processes of a
cutting device and a loading device
3.5
mixing/chopping device
element or set of elements that performs the mixing and/or chopping process(es) on the material in the
chamber
3.6
cutting device
element or set of elements attached to the machine that performs the cutting process
3.7
distribution device
element or set of elements, attached to the machine, which moves the material from the chamber to a desired
location
3.8
unloading door
moveable portion of the chamber that opens to unload material
3.9
moving floor
powered conveyor for moving the material within the chamber or on the loading door
3.10
workstation
position on the machine, other than the operator's station, from which control of at least some machine
operations is possible
ISO/DIS 4254-19.3:2026(en)
3.11
operator station
position of the operator during machine operations including transport
3.12
mineral hopper
a device for introduction of animal dietary supplement into the feed mixer
3.13
counter-knife (knives)
element(s) located close to the mixing and chopping device which restraints the feed material while it is cut,
shredded, impacted, and reduced
[SOURCE: ISO 7448:2024, 3.3.7 (modified)]
4 Safety requirements and/or protective risk reduction measures
4.1 General
4.1.1 Machinery shall comply with the safety requirements or protective risk reduction measures of
clause 4 of this document. In addition, the machine shall be designed according to the principles of relevant
clauses of ISO 12100:2010 for hazards relevant but not significant, which are not dealt with by this document.
4.1.2 Unless otherwise specified in this document, machinery shall comply with the requirements of
ISO 4254-1:2013 and with ISO 13857:2019, Table 1, Table 3, Table 4 and Table 6 as appropriate.
4.2 Controls
4.2.1 Controls located on the workstation or in the operator station
4.2.1.1 Controls shall be designed so that the operator can reach them where intended, for example by
means of an adjustable position.
4.2.1.2 It shall not be possible for the operator to reach unguarded moving working elements while
actuating the control.
4.2.1.3 It shall not be possible to reach the manual controls from inside the mixing/chopping chamber(s).
4.2.1.4 Stop controls shall have priority over all other controls.
4.2.1.5 Workstation controls shall be hold-to-run, except the following:
— controls for the mineral hopper;
— controls for the distribution device;
— controls to activate the automatic work cycle of the counter-knives, only for machines with a vertical
mixing/chopping device.
4.2.1.6 It shall be possible to deactivate the workstation controls to limit control of the machine to the
operator station only.
4.2.1.7 Two-hand controls shall comply with ISO 13851:2019.

ISO/DIS 4254-19.3:2026(en)
4.2.2 Remote controls
4.2.2.1 Remote controls and their electrical components shall comply with ISO 15817:2012 or IEC 60204-1.
4.2.2.2 The remote control shall:
— if wired or wireless, have a unique assignment of the remote control to the receiver to prevent operation
by other than the assigned remote controls; and
— be constructed in such a way as to prevent unintentional operation of the control devices that could
trigger dangerous movements (for example by means of protective collars or recessed buttons).
4.2.3 Emergency stop
An emergency stop control according to ISO 4254-1:2013, 4.19 shall be installed on self-propelled machines.
4.2.4 Safety and reliability of control systems
Safety and reliability of control systems shall conform with ISO 4254-1:2013, 4.20.
4.3 Visibility of work areas of cutting, loading and cutting/loading devices
4.3.1 Operator’s eye position
For the purpose of assessing visibility, the position of the operator’s eye is defined as shown in Figure 1
and Figure 3. A lateral displacement of the eye of the operator is allowed within ±300 mm from the centre
position.
4.3.2 For work area at front of the machine
4.3.2.1 The operator shall have visibility of the work area at the front of the machine from the operator
station and/or the workstation assessed from the eyepoint defined in 4.3.1.
4.3.2.2 The width of the work area is the entire width of any cutting, loading, and cutting/loading devices,
including any entrapment zones.
4.3.2.3 The height of the work area extends from the highest working position of any cutting, loading, and
cutting/loading devices to a height of 1 m or less from the ground when the machine is in its loading position
(see Figure 1).
4.3.2.4 The location of the work area is 200 mm measured from the edge of any cutting, loading, and
cutting/loading devices (see Figure 1).
4.3.2.5 When direct visibility is not achievable, the indirect visibility shall be provided by fitting machines
with devices such as mirrors, closed circuit television (CCTV) or other adequate system (see ISO 16001:2017).
Mirrors shall be used in a direct manner. Using one mirror to view another is not allowed.
4.3.2.6 Verification shall be by measurement.
4.3.2.7 Verification is achieved with the tools in the raised position. The position of the operator’s eye is
790 mm above the seat index point (SIP) as defined in ISO 5353:1995 (Figure 1).

ISO/DIS 4254-19.3:2026(en)
Dimensions in millimetres
Key
1 eye position
2 cutting/loading device
h visibility height range
Figure 1 — Checking of the direct visibility of a self-propelled machine
4.3.3 For work area at rear of the machine
4.3.3.1 The operator shall have visibility of the work area at the rear of the machine from the operator
station and/or the workstation assessed from the eyepoint defined in 4.3.1.
4.3.3.2 The width of the work area is the entire width of any cutting, loading, and cutting/loading devices,
including any entrapment zones [see d of Figure 2b) and 2d)].
4.3.3.3 The height of the work area extends from the highest working position of any cutting, loading,
and cutting/loading devices to a height of 1,5 m or less from the ground when the machine is in its loading
position.
4.3.3.4 The location of the work area is 200 mm to the rear of:
— the edge of any cutting, loading, and cutting/loading devices,
— the machine when the loading door is closed.
4.3.3.5 When direct visibility is not achievable, the indirect visibility shall be provided by fitting machines
with devices such as mirrors, closed circuit television (CCTV) or other adequate system (see ISO 16001:2017).
Mirrors shall be used in a direct manner. Using one mirror to view another is not allowed.
4.3.4 For work areas at sides of machine
4.3.4.1 The operator shall have visibility of the work area at the side of the machine from the operator
station and/or the workstation assessed from the eyepoint defined in 4.3.1.

ISO/DIS 4254-19.3:2026(en)
4.3.4.2 The width of the work area is 200 mm measured from the sides of any cutting, loading, and
cutting/loading devices of the machine [see Figures 2b) and 2d)].
4.3.4.3 The height of the work area extends from the highest working position of any cutting, loading,
and cutting/loading devices to a height of 1,5 m or less from the ground when the machine is in its loading
position.
4.3.4.4 The location of the work area is 200 mm to the rear of:
— the edge of any cutting, loading, and cutting/loading devices; or
— the machine when the loading door is closed.
4.3.4.5 When direct visibility is not achievable, the indirect visibility shall be provided by fitting machines
with devices such as mirrors, closed circuit television (CCTV) or other adequate system (see ISO 16001:2017).
Mirrors shall be used in a direct manner. Using one mirror to view another is not allowed.
4.3.4.6 Verification shall be by measurement on an empty machine.
Dimension in millimetres
a) Checking of the visibility for trailed machines with loading door - side view
b) Checking of the visibility for trailed machines with loading door – top view

ISO/DIS 4254-19.3:2026(en)
c) Checking of the visibility for trailed machines with cutting/loading tools – side view
d) Checking of the visibility for trailed machines with cutting/loading tools – top view
Key
h highest position to a maximum height of 1,5 m from the ground of the work area of the cutting/loading tools
and the loading door
d width of the loading tools
d width of the visibility area - interior width of the machine
d excluded width of the visibility area (sides of the machine)
Figure 2 — Checking of the visibility for trailed machines
Dimensions in millimetres
a) Case of clevis or hook-type connection between trailed machine and tractor

ISO/DIS 4254-19.3:2026(en)
b) Case of lower hitch point connection between trailed machine and tractor
Key
1 eye position
2 clevis or hook
3 ground
4 lower hitch point
Figure 3 — Determination of the conventional eye position
4.4 Loading devices
4.4.1 General
4.4.1.1 To avoid unexpected movement of the loading device during service and maintenance, locking
devices according to ISO 4254-1:2013, 4.11 shall be provided.
4.4.1.2 A means shall be provided to prevent the loading device from moving without being actuated
during transport according to ISO 4254-1:2013, 4.9.2.
4.4.1.3 The controls of loading devices shall be hold-to-run if outside of the operator's station, except for
the rotation of loading conveyors, which may be hold-to-run or require an intentional action (for example
manual control requiring two different actions to be operational, or protection rail around the manual
controls).
4.4.2 Loading door
4.4.2.1 When the loading door is open, at least one of the following measures shall be taken to protect
the operator against contact, entanglement and drawing-in hazards generated by the mixing/chopping
device(s).
— the mixing/chopping device shall not operate; or
— the mixing/chopping device shall only operate by a hold-to-run control; or
— the safety distances established in ISO 13857:2019, Tables 1, 3, 4 and 6 shall be maintained by an
automatically deployed protective device (for example, moveable interlocked wall).
4.4.2.2 To ensure the protection of the operator against crushing and shearing hazards related to a failure
of the hydraulic circuit, the door shall be fitted with a device to prevent unintended lowering (for example,
pilot-operated check valve), or with a device which limits the maximum downward speed of the door should
failure occur to 40 mm/s measured tangential to the trajectory of the outer edge of the door.

ISO/DIS 4254-19.3:2026(en)
4.4.2.3 A machine with a loading door that rises to close (the type of machine illustrated in Figure B.9 of
Annex B) shall allow the operator to remove the net wrap or strings from a bale after it has been loaded onto
the loading door:
— without entering the mixing/chopping chamber; and
— without operating the mixing/chopping device.
4.5 Cutting devices
4.5.1 General
4.5.1.1 The controls of cutting devices shall require an intentional action.
4.5.1.2 Cutting devices that pose a hazard when not in use shall be guarded, either
— by location, such as making possible and instructing the operator to position the cutting device(s) out of
reach. The repositioning of the cutting device(s) shall be possible from the operator’s station.
or
— directly with a guard that prevents inadvertent contact with the cutting device(s). The guard shall be
self-closing or actuated from the operator station.
4.5.1.3 In case of rotating cutting devices, the front guard shall be self-closing and shall extend on the
working front at least 110° from the vertical to the cutting device axis (see Figure 4), with the machine in
travelling position.
Key
1 front guard
α ≥ 110°
Figure 4 — Protection of rotating cutting devices when not in use
4.5.2 Stopping time
4.5.2.1 Requirements
4.5.2.1.1 The stopping time of cutting device(s) and cutting/loading device(s), from the moment the
control device is switched to the off position until the cutting device has come to a complete stop, shall not
exceed 10 s.
ISO/DIS 4254-19.3:2026(en)
4.5.2.1.2 It shall not be possible to reach unguarded cutting elements during the run-down time.
4.5.2.2 Measurement conditions
4.5.2.2.1 The cutting device shall not be under load.
4.5.2.2.2 The speed for the test shall be the nominal rotation speed as specified by the manufacturer.
4.5.2.2.3 If the cutting device is hydraulically driven the hydraulic oil temperature during the test shall be
(65 ± 5) °C.
4.5.3 Maintenance and repair
4.5.3.1 To avoid inadvertent lowering of the cutting device during maintenance and repair, locking devices
complying with ISO 4254-1:2013, 4.11 shall be provided.
4.5.3.2 Cutting devices shall be moveable as required for maintenance and repair without operating the
machine.
4.5.3.3 Cutting devices shall be lockable as required for maintenance and repair without operating
the machine. The hazards when changing blades during maintenance and repair shall be minimized by
design. For remaining hazards which can not be eliminated by design, instructions shall be provided in the
operator’s manual (see 6.1.4 c)).
4.5.4 Blockages
4.5.4.1 General
4.5.4.1.1 The machines shall be designed and built to minimize the probability and frequency of blockages
and to prevent a hazard arising should clearance of blockages become necessary.
4.5.4.1.2 This general requirement shall be achieved by the following risk reduction measures:
a) as far as practicable, avoid the need to approach the hazard zone by providing means to allow clearing
of blockages without interrupting the power to the machine, either from the operator's station or, if the
normal operation is controlled from workstation, from the workstation. Such means are for example:
— device to enlarge the section of passage of the material;
— reverse direction of the appropriate machine elements, independently from the cutting tools.
b) if a) is not fully achievable, assist in the clearing of blockages and cleaning after the machine is stopped,
by means of, for example:
— freewheel of the cutting tool axle to allow manual rotation without external power;
— hand tools to remove blockages.
4.5.4.2 Protection against inadvertent re-engagement in case of mechanical elements stopped by
blockage
Automatic restarting of hazardous movement following clearance of a blockage by an operator in the hazard
zone shall be prevented. A restart shall require the intentional actuation of a control outside the hazard zone
(for example, torque limiter reset which requires a complete stop of the PTO to be re-engaged).

ISO/DIS 4254-19.3:2026(en)
4.6 Mixing/chopping device
4.6.1 Guarding for a machine equipped with cutting, loading, or cutting/loading tools
If the machine is equipped with cutting, loading, or cutting/loading tools, safety distances for protection
against contact with hazardous moving parts of the mixing/chopping device shall comply with the safety
distances of ISO 13857:2019, Tables 1, 3, 4 and 6 when the cutting, loading, or cutting/loading tools are in
the position for mixing and/or chopping, the loading door is closed, or both.
4.6.2 Guarding for a machine equipped with gravity discharge
A machine equipped with a gravity discharge shall meet at least one of the following when the machine is
empty:
— guarding to the extent practicable that prevents unintentional contact with the hazardous moving parts
of the mixing/chopping device and that does not contact the mixing/chopping device when a horizontal
force of 500 N is applied;
— the safety distances of ISO 13857:2019, Tables 1, 3, 4 and 6 to prevent unintended contact with hazardous
moving parts of the mixing/chopping device;
— a distance ≥ 550 mm between the outermost edges of the discharge opening and the outer path of the
mixing/chopping device to ≥ 100 mm below a horizontal plane of the bottom edge of the discharge
opening (see Figure 5).
For machines with guarding only around the top and sides of the discharge opening, dimensions a and b
shall be as follows:
— If the distance h (see Figure 5) between the ground and the lower edge of the guard is ≤ 800 mm,
— dimension a shall be ≥ 550 mm; and
— dimension b shall be ≥ 100 mm
— If the distance h (see Figure 5) between the ground and the lower edge of the guard is > 800 mm,
— dimension a shall be ≥ 850 mm; and
— dimension b shall be ≥ 100 mm.

ISO/DIS 4254-19.3:2026(en)
Dimensions in millimetres
Key
a distance between the guard and the distributor cylinder
b vertical distance between the edge of the guard and the distributor cylinder
h distance between the ground and the lower edge of the guard
Figure 5 — Guarding to prevent unintended contact with mixing/chopping device (machine with
gravity discharge)
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