ONE APPLICATION OF THE INTERNATIONAL TERMINOLOGICAL

Proceedings of the 6th International Conference on Mechanics and Materials in Design,

Editors: J.F. Silva Gomes & S.A. Meguid, P.Delgada/Azores, 26-30 July 2015

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PAPER REF: 5691

ONE APPLICATION OF THE INTERNATIONAL TERMINOLOGICAL

STANDARD BDS ISO 10825 FOR THE DAMAGE IDENTIFICATION

ON THE TEETH OF GEAR TRANSMISSIONS

Valentin Abadjiev1, Georgi Dimchev

2, Emilia Abadjieva

1,3(*), Dimitar Karastoyanov

3

1Institute of Mechanics, Bulgarian Academy of Sciences, Bulgaria

2Technical University of Sofia, Bulgaria

3Institute of Information and Communication Technologies (IICT), Bulgarian Academy of Sciences, Bulgaria

(*)Email: [email protected]

ABSTRACT

Extremely dynamical development of the contemporary political processes of the

international integration demands on an adequately progress of the international scientific and

industrial collaboration. Hence, the question for introduction of the uniform, European and on

the international level terminology in the field of the basic characteristics of the engineering

resources is very important. This work treats one application of the international

terminological standard BDS ISO 10825 “Gears. Wear and Damage to Gear Teeth.

Terminology”, for solving a judicial dispute. The objective conclusion of the technical

specialist’s report, designated by the court, is defined.

Keywords: terminology standard, gear teeth damage, gear transmission.

INTRODUCTION

Some terms and definitions for standardization

The specific thematically orientation of the current work requires to define in advance the

following basic terms and definitions related to the term "standardization" and adequate its

derivatives (BDS EN 45020:2007, 2007):

• Standardization. Activity of establishing, with regard to actual or potential problems,

provisions for common and repeat use, aimed at the achievement of the optimum

degree of order in a given context.

• International standardization. Standardization in which evolvements is open to

relevant bodies from all countries.

• Standard. Document, established by consensus and approved by a recognized body,

that provides, for common and repeated use, rules, guidelines of characteristics for

activities of their results, aimed at the achievement of the optimum degree or order in

given context.

• International standard. Standard that is adopted by an international

standardizing/standards organization and made available to the public.

• Regional standard. Standard that is adopted by a regional standardizing/standards

organization and made available to the public.

• Basic standard. Standard that has a wide ranging coverage or contains general

provisions for one particular field.

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Tribology, Gears and Transmissions

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• Terminology standard. Standard that is concerned with terms, usually accompanied by

their definitions, and sometimes by explanatory notes, illustrations, examples, etc.

The introduced terms and definitions are oriented to the specifics of the accomplished bellow

expert assessments of the wears and damages of the studied transmission, when analyzing its

operational suitability.

Essence of the problems

The extremely dynamic development of the contemporary political processes, which are

connected with the enlargement of international political, military and economical unions,

determine a natural dynamic of the international scientific and industrial collaboration

processes. These processes also determine an extremely active economical exchange between

different in their technical and technological level business structures. Therefore the question

for the introduction of a uniform not only on a European but also on an international level,

terminology in the field of the basic aspects of the engineering resources is very important.

Such elements of that group of engineering resources are all types of gears. Hence a uniform

world terminology in the field of gears geometry, firmness, manufacture technology, gears

damages and wearing out should be introduced in the national standardization documents.

For decades structures like Council for Mutual Economic Assistance (former economical

structure of the East European countries), ISO, national standardization institutions and

private certification organizations have worked and still work in the area of terminological

unification. The approaching method, which basically is a development and approval of the

national terminological standards, is inconsistent with the development of the European and

world integration processes in the scientific, technical and manufacture areas (Arnaudov,

1990).

The process of using a uniform terminology in every single direction of science should be

treated as an element of strategy. This strategy is connected with the European and world

integration processes.

The mentioned method eliminates problems, which are local in character and are due to the

linguistic specificity and national terminological traditions in the particular engineering area.

This work is dedicated to the application of ISO 10825 “Gears. Wear and Damage to Gear

Teeth. Terminology” in the solution of a court dispute, concerning the damage of the

mechanical transmission elements of a tractor model URSUS 1634. The tractor has been used

only during its guarantee period. (Abadjiev, 2004)

An expert’s report was made, which is a base for the court solution of the mentioned case.

This expert’s report was worked out with the application of the identical Bulgarian edition of

the normative document – BDS ISO 10825. The Bulgarian edition of the latest document,

which is prepared by the first two authors of this study, was published in 1995.

THE BASIC CHARACTERISTIC OF THE STANDARD BDS ISO 10825

The basic characteristics of this document are shown in its rubric “Area of application” (BDS

ISO 10825, 1997). The BDS ISO 10825 determines the terms, which are used for description

of the flanks of the teeth or the description of the damages, which could be observed on the

gear mechanisms.

It is given the short and exact description for every term. This description includes the

important features of the tooth surfaces of the gear for identification of the shown wear or the

damage.



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Every classified external view of a wearing or a damage of the teeth is illustrated with one or

more pictures, which are typical examples of one or several teeth. At some cases are shown a

several illustrations of the concrete tooth or the type damage, which show the existence of

possible variants or differences, which can exist for the different teeth geometry. Every

illustration is accomplished with a comment to facilitate an explanation.

This international standard is only terminological. It is worked out to assist for identification

the type’s damages and to determine the condition of the gears, after a period of exploitation.

To achieve this goal, the standard doesn’t contain any information for the possible reasons

and а prevention methods for the established conditions. But the general conditions are well

known only by the specialists due to their accumulated operational experience.

APPLICATION

The complete standard document, which treats the different types of wear and damages to the

gear mechanisms, did not exist in Bulgaria till 1997. Some basic damages, related to strength

calculation of the gears are partially mentioned in (BDS 17108-89, 1991). The presence of the

BDS ISO 10825 fills the gap in the field of standardization of gear mechanisms and it is used

in designer’s practice and in student’s training. Besides purely engineering application, this

standard is important for jurisprudence for classification of observed damage caused

mechanism’s crashes.

Such is the case for the technical expert’s report preparation. The report refers to the occurred

crashes in mechanical transmissions of two tractors brand URSUS 1634, import from Poland.

This expert’s evaluation, which is elaborated for the needs of the court, contains the following

classification of the established damages on the teeth of the gears of the studied transmissions:

Planet cylindrical gears (Fig. 1, Fig. 2)

Fig. 1 - Planet carrier with spur cylindrical gear from the tractor URSUS 1634 transmission

� Indentation (BDS ISO 10825, pp. 27, 1997). The large numbers of depressions on the tooth

flanks are caused by a passing through the mesh region foreign bodies during the meshing

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period. The classification of the damages into this category is based on their type and on

the fact that the different groups of depressions are situated in vicinity of a plane,

perpendicular to the geometrical axis of the cylindrical gear. (Fig. 3)

Fig. 2 - Planet cylindrical gears from the tractor URSUS 1634 transmission

Fig. 3 - Indentation (BDS ISO 10825, pp. 27, 1997): The depressions in the active tooth flanks are caused by the

foreign bodies (metal particles) during the meshing

� Plastic deformation (BDS ISO 10825, pp. 28, 1997). The observed dents on the teeth and

the displacement of the material can be explained with the exploitation under high loading

and friction conditions.

� Overload breakage (BDS ISO 10825, pp. 51, 1997). The breakage of the teeth of the

planet cylindrical gears is characterized with fracture surface of damage. On the page 53,

of BDS ISO 10825, it is illustrated the breakage of the small cylindrical gear. The fracture

structure dues of to the damage. This damage is in result of high alternating load (brittle

fracture) (Fig. 4).



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Fig. 4 - Ductile fracture (BDS ISO 10825, pp. 53, 1997): The breakage, as a result of the overload of the teeth of

the small gear. There are simultaneously brittle fracture (BDS ISO 10825, pp. 52, 1997) and ductile fracture

Central cylindrical gear

� Indentation (BDS ISO 10825, pp. 27, 1997) and broken after a plastic deformation (BDS

ISO 10825, pp. 51, 1997). The indentations are accomplished with plastic deformations.

The character of these deformations can be explained with the fact, that the central

cylindrical gear is meshed at the same time with three planet cylindrical gears. That is

why; there are a bigger number of foreign bodies, which passes between conjugate tooth

surfaces in the processes of work meshing. The discussed here damages are not illustrated.

Conic pinion and crown (Fig. 5, Fig. 6)

Fig. 5 - Conical pinion and crown from the tractor URSUS 1634 transmission

� Indentation (BDS ISO 10825, pp. 27, 1997). The damages classified in this group are

characterized by the same reasons, which are defined in the cylindrical gears’ section.

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Fig. 6 - Conical pinion from the tractor URSUS 1634 transmission

� Breakage (BDS ISO 10825, pp. 56, 1997). The broken edges of the teeth of the conic

pinion and the crown can be explained with bearing inaccuracy. These type spatial gear

mechanisms are sensitivity to the bearing inaccuracy (hypoid and conical gears with spiral

teeth). This cause edge contact and non-uniform loading between meshed teeth (Fig. 7).

Fig. 7. Breakage (BDS ISO 10825, pp. 56, 1997): The both illustrations show, that from all teeth of the gears are

broken edges or parts, that are close to the tips of the teeth. Those two gears are damaged due to inaccurate

assembling, that caused non-uniform loading of the meshed teeth



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CONCLUSIONS

The realized study covers the analysis of the gears robust and the lubrication of the gear

mechanisms:

� The central gear measured robustness on the gear flanks is 60-62Rc, and in the base of the

gear is 50-59Rc. Planet gear obtains robustness from 50-52Rc at its gear flanks, and in

the core of the gear is 49-50Rc. The measured robustness is an ordinary for the gear

flanks of these type gear mechanisms. This robustness confirms the fact, that the gear

mechanisms are elaborated from low carbon lubricated steel. After that they are

adequately thermo-chemically treated.

� The lack of damages, which are classified accordingly BDS ISO 10825 “Sliding wear”

(pp. 5-7), “Polishing” (8pp.), and “Scratching (scoring)” (pp. 12-13), are evidence, that

the spreading of the gear mechanisms, is accomplished with optimal oil for operational

gear transmission.

The classification of the damages of the studied gears helps to define the objective conclusion

about the reason of damage appearance. These gears are part of the structure mechanical

transmissions of two tractors URSUS 1634.

The final expert conclusion is: “The documented damages are result of considerable overload.

This overload causes the defined breaks. The defined damages are in result of non-uniform

loading of the meshed teeth, which is caused by inaccurate assembly of the gear pair. The

other reason for the damages is occurring of the foreign bodies between teeth of the gears.

This foreign bodies impact over the tooth flanks in the process of the work meshing”.

ACKNOWLEDGMENTS

The authors gratefully acknowledge the funding by project AComIn: Advanced Computing

for Innovation of the FP7 Capacity Programme, Research Potential of Convergence Regions,

FP7-REGPOT-2012-2013-1

REFERENCES

BDS EN 45020:2007. Standardization and related activities - General vocabulary (ISO/IEC

Guide 2:2004), Publishing House “Standardization Print Co”, Available from 2007-09-28. 63

pp.

Abadjiev V, Dimchev G, Abadjieva Е. An application of ISO 10825 in the solution of the

court dispute, 12 International Scientific Conference CO-MAT-TECH 2004, 14-15 October

2004, Trnava, Slovak Republic, 2004, Published on CD.

Arnaudov K, Minkoff K, Parushev P, Bojdev V, Takov I. On the problem of an unique

international terminology in the gear mechanisms Area. Vestnik Mashinoctroeniq (Monthly

Journal for Science, Techniques and Manufacture), № 12, Mashinostroenie, Moscow, 1990, p.

14 – 17.

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BDS ISO 10825. Gears-wear and damage to the gear teeth .Terminology. Publishing House

“Standardization Print Co.”, № 17, Sanction on 1996-07-31, Available from 1997-01-01. 64

pp.

BDS 17108-89. Cylindrical, involutе gear mechanisms with external meshing. calculation of

the robustness of the gear teeth. Publishing House “Standardization Print Co”, № 529,

Sanction on 1989-12-29. Available from 1991-01-01. 124 pp.

Documents

ONE APPLICATION OF THE INTERNATIONAL TERMINOLOGICAL