ISO 21120:2025

International
Standard
ISO 21120
First edition
Machinery for forestry — Forestry
2025-01
mulching equipment — Terms,
definitions and commercial
specifications
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms .1
3.2 Terms related to mulching attachment carrier .2
3.3 Terms related to to mulching attachment .2
3.4 Terms related to mulching equipment type .3
3.4.1 Drive type .3
3.4.2 Rotor type .3
3.4.3 Tool type .3
3.4.4 Mount type . . .4
3.5 Terms related to dimensional characteristics.4
3.5.2 Mulching attachment carrier .4
3.5.3 Mulching attachment .5
3.5.4 Mulching equipment . .5
3.6 Terms related to masses .6
4 Commercial specifications . 6
4.1 Mulching attachment carrier .6
4.1.1 Internal combustion engine .6
4.1.2 Electric motor .6
4.1.3 Undercarriage .6
4.1.4 Mulching attachment carrier mass .7
4.2 Mulching attachment .7
4.2.1 Drive type .7
4.2.2 Rotor type .7
4.2.3 Dimensional characteristics .7
4.2.4 Mulching attachment mass .8
4.3 Mulching equipment .8
Annex A (informative) Dimensional characteristics of forestry mulching equipment. 9
Annex B (informative) Nomenclature of forestry mulching equipment .13
Bibliography .18

iii
Foreword
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forestry, Subcommittee SC 15, Machinery for forestry.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv
Introduction
The figures in this document are intended to illustrate machine concepts for rather than any existing
machines or all possible configurations (see Annexes A and B).

v
International Standard ISO 21120:2025(en)
Machinery for forestry — Forestry mulching equipment —
Terms, definitions and commercial specifications
1 Scope
This document identifies and defines terms, specifies a means of classification, provides dimensional
characteristics and commercial specifications, and gives a nomenclature of components for mulching
equipment (in other words, mulching attachment carriers and mulching attachments) used in forestry and
related operations. Its aim is to establish a uniform method of describing the various configurations of these
types of forestry machines.
Machines for mulching which have been designed for feeding by hand are not covered by this document.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology 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 General terms
3.1.1
mulching attachment carrier
self-propelled machine for carrying a mulching attachment (3.1.2)
Note 1 to entry: Mulching attachment carriers are defined by their design configuration and operational purpose.
EXAMPLE Skid-steer loader, excavator, tractor with forestry application features.
3.1.2
mulching attachment
device affixed to and propelled by a mulching attachment carrier (3.1.1) and designed for the purpose of
mulching (3.1.3)
3.1.3
mulching
reduction of trees, brush, or parts of trees on site with a grinding or shredding action, leaving the resulting
material on the forest or worksite floor
[SOURCE: ISO 6814:2009, 2.16, modified to add: or worksite]

3.1.4
mulching equipment
mulching attachment carrier (3.1.1) equipped with a mulching attachment (3.1.2)
Note 1 to entry: Mulching equipment can be classified by how they are configured (for example, drive type, rotor type,
tool type, mount type) and combination of these types. See 3.4
3.2 Terms related to mulching attachment carrier
3.2.1
undercarriage
base of the mulching equipment (3.1.4) that provides mobility
Note 1 to entry: An undercarriage typically has endless tracks or wheels, or a combination of both.
3.2.2
maximum ground speed
maximum forward speed able to be obtained on level ground based on the nominal design capacity of the
mulching attachment carrier (3.1.1) with tyres or endless tracks
Note 1 to entry: The tyre size will be the largest diameter drive tyres as specified by the mulching attachment carrier
manufacturer for the mulching attachment carrier (3.1.1).
3.3 Terms related to to mulching attachment
3.3.1
rotor
rotating component with tools (3.3.2) that strikes and reduces material it comes in contact with
Note 1 to entry: The rotor typically has an axis that is either horizontal (drum type) or vertical (disc type).
3.3.2
tool
material engaging element mounted to the rotor (3.3.1) that grinds, shreds, tears, or cuts material
EXAMPLE Tooth, hammer.
3.3.3
anvil
reaction element or elements located close to the rotor (3.3.1) which restrains engaged material while it is
struck and reduced by the tools (3.3.2)
3.3.4
rotor housing
enclosure containing the rotor (3.3.1) and reactionary elements which limit and direct material discharge
3.3.5
debris sizing door
adjustable element mounted on the rotor housing (3.3.4) that contributes to material reduction and directs
material discharge
3.3.6
push bar
pushover bar
rigid or adjustable structure mounted on top of the rotor housing (3.3.4) for manipulating and directing
material that is standing or on the ground
3.3.7
skid shoe
adjustable or rigid mounted element mounted at the bottom of the mulching attachment (3.1.2) outside of the
rotor housing (3.3.4) that regulates distance between the cutting element and the ground

3.3.8
mount
mechanical interface that connects the mulching attachment (3.1.2) to the mulching attachment carrier (3.1.1)
typically by welding, bolting, or pinning
Note 1 to entry: Quick couplers and quick attach systems are
...