ISO 14635-2:2023

INTERNATIONAL ISO
STANDARD 14635-2
Second edition
2023-07
Gears — FZG test procedures —
Part 2:
FZG step load test A10/16, 6R/120
for relative scuffing load-carrying
capacity of high EP oils
Engrenages — Méthodes d'essai FZG —
Partie 2: Méthode FZG A10/16, 6R/120 à paliers de charge pour
évaluer la capacité de charge au grippage des huiles à valeurs EP
élevées
Reference number
© ISO 2023
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Failure criteria .2
5 Brief description of method . 4
5.1 General principle . 4
5.2 Precision . . . 4
6 Test materials . 4
6.1 Test gears . 4
6.2 Cleaning fluid . 4
7 Apparatus . 4
7.1 FZG spur-gear test rig. 4
7.2 Heating device . 6
7.3 Revolution counter . 6
7.4 Balance . 6
8 Preparation of apparatus .8
9 Test procedure .8
10 Reporting of results .9
Annex A (informative) FZG A10-type gear tooth face changes (flank damages) .11
Annex B (informative) Typical FZG test report sheet .13
Annex C (informative) Checklist for maintenance of FZG gear test rig .14
Bibliography .19
iii
Foreword
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electrotechnical standardization.
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 60, Gears, Subcommittee SC 2, Gear
capacity calculation.
This second edition cancels and replaces the first edition (ISO 14635-2:2004), of which it constitutes a
minor revision. The changes are as follows:
1)
— ISO 1328-1:1995 has been dated as this document uses accuracy grade which is numerically
different than tolerance class in ISO 1328-1:2013;
— replacement of ISO 4287 which has been withdrawn and replaced by ISO 21920-2;
— replacement of ISO 4964 which has been withdrawn and similar information can be found in
ISO 18265;
— replacement of some bibliography entries which were withdrawn, and changes from dated to
undated references;
— subclause 6.2, wording harmonized with the ISO 14635 series;
— Table 2, description "pitch diameter circumferential speed (v )" has been replaced by "circumferential
w
velocity at the pitch line" to harmonize the wording with the ISO 6336 series;
— Table 5, insertion of line "Test lubrication volume" to conform to the information in the ISO 14635
series;
— Figure A.1, addition of the figure title.
A list of all parts in the ISO 14635 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.
1) Cancelled and replaced by ISO 1328-1:2013.
iv
Introduction
The types of gear failures which can be influenced by the lubricant in use are scuffing, low-speed
wear and the gear-surface fatigue phenomena known as micro- and macropitting. In the gear design
process, these gear damages are taken into consideration by the use of specific lubricant and service-
related characteristic values. For an accurate, field-related selection of these values, adequate lubricant
2)
test procedures are required. The FZG test procedures specified in this document, ISO 14635-1 and
ISO 14635-3 can be regarded as tools for the determination of the lubricant-related characteristic
values to be introduced into the load-carrying capacity calculation of gears.
FZG test method A/8,3/90 for the relative scuffing load-carrying capacity of oils described in
ISO 14635-1 is typical for the majority of applications in industrial and marine gears. This document
is related to the relative scuffing load-carrying capacity of oils of very high extreme pressure (EP)
properties, as used for the lubrication of automotive driveline components. Other FZG test procedures
for the determination of low-speed wear, micro- and macropitting load-carrying capacity of gears are
intended to be added to the ISO 14635 series as further parts.
2) FZG = Forschungsstelle für Zahnräder und Getriebebau, Technische Universität München (Gear Research
Centre, Technical University, Munich).
v
INTERNATIONAL STANDARD ISO 14635-2:2023(E)
Gears — FZG test procedures —
Part 2:
FZG step load test A10/16, 6R/120 for relative scuffing
load-carrying capacity of high EP oils
1 Scope
This document specifies a test method based on a FZG four-square test machine to determine the
relative load-carrying capacity of high EP oils defined by the gear surface damage known as scuffing.
This test method is useful for evaluating the scuffing load capacity potential of oils typically used with
highly stressed cylindrical gearing found in many vehicle and stationary applications. It is not suitable
for establishing the scuffing load capacity potential of oils used in highly loaded hypoid bevel gearing
applications, for which purpose other methods are available in the industry.
NOTE This method is technically equivalent to CEC L-84-02.
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.
3)
ISO 1328-1:1995 , Cylindrical gears — ISO system of accuracy — Part 1: Definitions and allowable values
of deviations relevant to corresponding flanks of gear teeth
ISO 14635-1, Gears — FZG test procedures — Part 1: FZG test method A/8,3/90 for relative scuffing load-
carrying capacity of oils
ISO 18265, Metallic materials — Conversion of hardness values
ISO 21920-2, Geometrical product specifications (GPS) — Surface texture: Profile — Part 2: Terms,
definitions and surface texture parameters
ASTM D 235, Standard Specification for Mineral Spirits (Petroleum Spirits) (Hydrocarbon Dry Cleaning
Solvent)
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) Cancelled and replaced by ISO 1328-1:2013.
3.1
scuffing
particularly severe form of gear tooth surface damage in which seizure or welding together of areas
of tooth surface occur, owing to the absence or breakdown of a lubricant film between the contacting
tooth flanks of mating gears, typically caused by high temperature and high pressure
Note 1 to entry: Scuffing is most likely when surface velocities are high. It can also occur at relatively low sliding
velocities when tooth surface pressures are high enough either generally or, because of uneven surface geometry
and loading, in discrete areas.
3.2
scuffing load-carrying capacity
〈of a lubricant〉 maximum load which can be sustained under a defined set of conditions
Note 1 to entry: It is the minimum load stage at which the failure criterion given in Clause 4 is reached. See
Table 1.
3.3
FZG test condition A10/16,6R/120
test condition where A10 is the particular tooth form of the test gears, according to Tables 2 and 3,
16,6 is the speed at the pitch circle, in metres per second, “R” indicates the reverse direction of rotation
(wheel drives pinion) and 120 is the initial oil temperature in degrees Celsius, from load stage 4 onward
in the oil sump
3.4
failure load stage
load stage reached when the sum of the damage to the 16 pinion teeth exceeds 100 mm in total area
damaged
Note 1 to entry: See Clause 4 and Table 1.
3.5
high EP oils
lubricants containing chemical additives appropriate for improving
...