Tyre manufacturer Mitas is breaking new ground with development of a rapid central tyre inflation system, designed to make operation much more convenient. Jane Carley reports.
Developed initially for Fendt’s 900 Vario series tractor, tyre sizes offered will be Mitas’ 710/75 R42 SFT and 710/70 R42 SFT.
Choosing the correct tyre pressures for a particular task can increase efficiency considerably, as well as cutting tyre wear and boosting safety. However, it is not always practical to alter tyre pressures between jobs, when ground conditions change or even between field and road.
Over the years manufacturers have dabbled with on-board tyre inflation systems – notably Mercedes Benz with the Unimog – but such systems can to be costly to fit and slow to operate.
To overcome this, tyre manufacturer Mitas has taken the technology into the tyre itself with AirCell, a new inner tyre design which enables the inflation of large agricultural tyres by +/- 1 bar (from 0.8 bar to 1.8 bar) within half a minute - more than 10 times faster than the current method of inflation.
The system is located on the rim inside the tyre and occupies about 30 per cent of the volume of the tyre. It has been designed initially for the Mitas 710/75 R42 SFT and 710/70 R42 SFT tyre model with other sizes to follow.
AirCell is continuously inflated to a maximum of 8 bar during the tyre’s use, releasing some of the pressure on demand enabling a rapid increase of pressure into the tyre itself, and adjusting the pressure in seconds rather than minutes.
Hans-Ulrich Klose, head of the automotive engineering at Mitas says; “AirCell was developed to reduce tyre filling waiting time, cut fuel costs, protect the soil, increase the life of the tyre and improve handling characteristics during on-road transportation.”
“Farmers and contractors who need to change pressures quickly from low inflation during field work to higher pressure for better fuel efficiency during on-road transportation and vice versa will see real benefits.”
Cutaways of the Mitas AirCell show the inner tyre, essentially a reservoir of pressurised air, which is released on demand into the cavity of the normal tyre.
An important characteristic of AirCell is that it not only enables rapid tyre inflation but it also helps to release the pressure just as fast again as the volume of the outer tyre is reduced by up to 30 per cent, the company points out.
The AirCell unit is not in contact with the tyre itself and so it does not create any additional friction or heating. It is made from sturdy rubberised materials and is designed to retain its shape even when inflated to high pressures, syas the manufacturer, so the volume of the outer tyre does not depend on the inflation of AirCell.
Currently, AirCell is initially only available as as an option for the Fendt 900 Vario tractor, equipped with Mitas 710/75 R42 SFT tyres from November 2016. Partnered with Fendt’s VarioGrip Pro tyre inflation management system, it allows operators to alter tyre pressures on the move.
Tyre pressure is set using the Fendt Varioterminal and the air pressure can be adjusted for each individual wheel. Additional safety is provided through continuous monitoring of tyre pressure. For example, damage to the tyre can be quickly detected through a drop in air pressure.
The sensor system and valve assembly of the VarioGrip Pro tyre pressure regulation system are attached directly to the wheel, so control commands, sensor data and electric energy are transferred between the wheel and tractor body without contact, and thus without wear, says Fendt.
Mitas sales and marketing director Andew Mabin comments: “AirCell was developed together with Fendt and is an integrated component of Fendt VarioGrip Pro. The full utilisation of advantages of AirCell can only be realised with a tyre inflation management system such as the Vario Grip Pro. But in general, all types of tyre inflation systems could be supported by AirCell.”
Fednt previously offered the VarioGrip system which used the tractor’s own air system to inflate or deflate standard tyres on the move, but the new development offers considerable time savings over its predecessor.
In contrast with the previous Vario Grip system, engine speed does not need to be increased to achieve the shorter filling times, saving fuel and reducing noise emissions.
Mitas AirCell is mountable on standard tractor rims using standard tools and can be repaired with kits used for bias tyres in the event of a puncture. Wheels can also be ballasted using weights attached to rims, but the design is not suitable for water ballasting.
The tyre is to be manufactured at Mitas’s factory in the Czech Republic and a decision on how much of a premium over a standard tyre cost will be charged has not yet been finailsed, says the company.