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21/03/2018
New UNI 11691 standard: "Tire demounting and mounting machines for vehicles - Safety requirements"

The tire specialist

 

On October 31, 2017 the new UNI 11691 standard was published as part of the national regulatory body, which specifies that "this standard provides safety requirements and their verification to the design and manufacture of tyre demounting and mounting machines for vehicles in order to obtain a correct assembly of tyre on the wheel under safe conditions".

Donaldo Labò

The relentless technical evolution in the automotive field, with increased performances, greater safety, new designs and growing environmental awareness has, over the years, focused on two vital safety components, wheels and tires. As types and sizes, technical characteristics and the combination of such elements keep multiplying, very specific operations need to be followed in order to ensure the best final result in full compliance of existing safety requirements.

On October 31, 2017 the new UNI 11691 standard was published as part of the national regulatory body, which specifies that "this standard provides safety requirements and their verification to the design and manufacture of tyre demounting and mounting machines for vehicles in order to obtain a correct assembly of tyre on the wheel under safe conditions".

As always, CUNA - Technical Unification Commission in the Automotive sector, a UNI federated body – was responsible for elaborating the new standard on behalf of manufacturers of garage equipment, tires, vehicles and other interested entities such as INAIL, etc.

 

All significant hazards and conditions of use related to these types of machines when used in accordance with the manufacturer's instructions or under conditions of reasonably foreseeable misuse, according to the principles contained in the Machinery Directive 2006/42/EC, are covered. The appropriate technical measures are therefore defined to eliminate or reduce all possible risks or dangerous conditions during transport, work and maintenance operation. As established in the EN ISO 12100: 2010 regulation, this is a type C standard, which indicates the detailed safety requirements applicable to single machines, or groups of specific machines. When the provisions of a type C Standard differ from the more general ones indicated in type A or B standards, the former have the priority over others.

 

As far as the field of application, the regulation specifies that this first standard covers equipment for tire demounting and mounting operations on vehicles belonging to international categories such as M1, M2, N1, O1, O2, L4 and L5, i.e. cars , buses, lorries, trailers up to a total mass of 3.5 t, in addition to trolleys, quadricycles, motorcycles, mopeds and agricultural machines where the dimensions of the tires are compatible with the maximum dimensions indicated in the instruction manuals.

 

The Definitions chapter, right at the beginning, confirms that the definition "specialist", as reported in other technical standards, refers to "a person qualified to perform the operation within an enterprise equally qualified to carry out such activity". The following chapter deals with a list of significant hazards grouped by type: mechanical, electrical, noise, ergonomics, etc. Describes dangerous situations and events, from the crushing of upper or lower limbs, to impacts, pressurized fluid ejections or explosion of tire/rim/wheel assembly due to improper mounting. At this point, one would have to refer to the corresponding safety requirements and/or protection measures described in the successive chapter, from control devices, types and positions, to protections and additional measures. Both the operating space and danger zone are identified in plan and front view. The maximum speeds of linear displacement and angular rotation of moving parts are also indicated, as well as the presence of pressure relief valves both for the tank and for the setting phase with the relative values, and the presence of a pressure gauge in compliance with UNI EN 12645 standards.

In the chapter "instructions for use", we are reminded that these are an integral part of the machine's supply package, and must include text, words, signals, symbols or diagrams in terms of marking, operating instructions and specific demounting/mounting instructions. Appendix A - disclosure - shows some classification examples of these machines in the table. Appendix B - disclosure - includes examples of protection against accidental operation. Appendix C – disclosure – provides examples of pictograms to be used on the equipment and on the instructions for use of the equipment itself, with references to the current ISO standards.

Appendix D - standards - discloses the information that the manufacturer must include in the instructions for use and maintenance for the correct demounting / mounting operations on UHP (Ultra High Performance) and RFT (Run-Flat) tires. UHPs are the most recent and advanced high performance products, with greatly reduced profiles. Run-flats are also defined as "self-supporting", i.e. able to run even at zero pressure for many kilometres, albeit at low speed (normally max 80 km/h), guaranteeing the safest possible control of the vehicle. They must be originally supplied as standard equipment and have led to the creation of the TPMS pressure control system. In both cases the reduced flexibility of the sidewalls require precautions in the positioning and use of tools to limit tensions on the beads and on the sides, in addition to protecting the sensors.

The new UNI 11691 therefore constitutes a precise reference for the sector, whether manufacturers, users or repairers.

The Machinery Directive in force lists, in the 2nd Annex, the content of the EC declaration of conformity of a machine. In particular, it specifies that, if necessary, reference can be made to other rules and technical specifications if applicable. With this standard, tire-changer’s manufacturers can now, if the provision have been implemented right from the designing phase,  add the marking "standards and technical specifications used: UNI 11691 October 2017".

Mounting and safety issues, the underlining motivations behind the new standard, are obviously present not only on our national territory, given the circulation of vehicles. Since there is no similar standard in other European countries, a formal request has already been made to the competent Technical Committee of the CEN (European Standardization Committee) to extend such measures at European level.

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