ATF technology rises to the
challenge part 2
In Part 1 of this two part feature, The Strategy Works examined the commercial forces driving the ATF market in Europe. In part 2 we examine the technical findings from the research and assess how the ATF supply chain is responding to the needs of service managers both now and in the future.
Commercial Vehicle type impacts on ATF choice The most common vehicle types such as city buses, refuse trucks, etc. with the typical ‘stop/go’ driving profile, place their own demanding conditions on the type of ATF and its performance. The more payload the vehicle has to carry, the higher the stress the ATF within the gear unit has to sustain, often due to extremely high temperatures. These can arise from insufficient cooling due to slow speed of the vehicle and/or high ambient temperature.
Using an approved premium quality ATF extends drain intervals as long as possible and enhances transmission performance and durability in all operating environments throughout the interval.
Key Technical Requirements of ATF: • Lubrication of sliding/rolling parts • Internal cooling of gears by transporting heat to transmission housing or separate oil cooler
• Protection against corrosion, wear, deposits and foam • Durability to allow long drain intervals • Elastomer-compatibility: sealing materials must not become brittle or soft and they must not shrink or swell
• Application specific friction characteristics in clutches or brake bands for shift-comfort and torque capacity
• Torque transfer in gears and torque converter and variator (CVT)
• Viscosity optimum for cold start as well as high temperature operation
These features need to be viewed in the context of the features that Service Managers most value as indicated by the research:
Transmission Reliability and Durability This can only be achieved if the ATF itself is designed for sufficient protection against the wear & tear of the transmission hardware. The ATF anti-wear- performance, must be adjusted with the gear unit´s demand, deriving mainly from vehicle operating conditions including environmental thermal stress.
Michael Herson
Bernd Heyse
It is therefore important to decide on the right ATF as Alexander Roder, Service Manager at OVK Kirchheim, explains “The company wants to ensure that the transmissions last for 8 years. So we procure exactly the ATF recommended to us.”
This is endorsed by the technical coordinator at a leading French truck operating company: “Transmission reliability and durability is linked with the longevity of the vehicle”.
A leading bus company in Turkey stresses the importance of this feature: “Protection against wear/tear is a valuable feature for modern ATFs. Since we operate more than 200 buses in the city, so smooth operation of the buses in alignment with our routine maintenance cycles is very important for our operations.”
Oil Drain Intervals
The length of the oil drain interval is driving the operating efficiency of a vehicle or fleet. OEM’s test and approve selected ATF products for individual applications, interval length and operating conditions.
ATF suppliers have responded to transmission manufacturers (e.g. ZF EcoLife transmission box, ODI up to 240,000 km / all 4 years) by introducing leading edge products mostly based on an advanced synthetic technology, allowing extended long drain intervals for the demanding requirements of modern, full automatic, heavy duty gearboxes. Synthetic ATF products offer increased resistance to heat peaks as overheating can lead to ‘coking effects’, causing oil thickening. These types of products also offer enhanced protection against deposits and corrosion, contributing towards extended transmission life.
Corrosion; Wear & Tear; Thermal / Heat Conductivity Typical thermal stress factors are stop/start driving profiles, high loads and high external temperatures, often co-occuring. The ATF has to deflect heat from inside to outside the gear box which has a cooling effect. Beyond cracking of the oil molecular chains over the operation time can lead to viscosity change, loss of lubricity and depletion of friction properties. The oil may become thinner, leading to shifting problems and finally to increasing wear. This is confirmed by two service quotes below:
Ahmet Kucuk, Coordinator for Repairs at Ozemniyet Turizm Ltd in Turkey comments, “We value the thermal protection that comes with ATF with constant starts and stops.” Herr Doeffinger,
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LUBE MAGAZINE NO.133 JUNE 2016
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