AutoFocus #13, December 2010
DuPontTM VespelŪ SP-21 thrust washers replace metal, cut weight, space and friction in the latest JATCO 7-speed automatic transmission
Automotive engineers cannot afford to take chances with materials used for vehicles in commercial production. Longer warranty periods, the severe cost penalties of component failure and model recalls have made automotive materials specifiers highly risk-averse. That's why, when a component is selected for use on production models, it has survived exhaustive testing and comparisons to alternatives.
DuPontTM VespelŪ parts are perfect examples of components that have earned the trust of many demanding automotive engineers and designers, following years of service in thousands of applications. As a result, VespelŪ thrust washers, seal rings, bushings and other vital friction and load bearing parts are widely specified by the automotive industry.
VespelŪ SP-21 thrust washers located between the aluminum die cast case and second clutch at right of JATCO 7-speed automatic transmission, replace larger, heavier metal thrust needle bearings to save weight and space, and enhance fuel efficiency.
When JATCO Ltd., of Shizuoka, Japan, a key supplier of powertrain systems to Nissan, Renault, Suzuki and other major auto manufacturers, looked for polymer thrust washers to replace larger and heavier metal thrust needle bearings for its latest 7-speed automatic transmission (AT), the company chose VespelŪ parts.
VespelŪ SP-21 thrust washers are thinner and lighter than comparable metal thrust needle bearings. In addition, they can rotate directly against the aluminum housing, allowing a reduction in the number of parts, and easier assembly. These advantages helped engineers at JATCO reduce the overall size and weight of the AT unit.
Weight and space saving were not the only reasons. VespelŪ SP-21 parts can withstand pressure velocity (PV) loads of up to 40 MPa m/s in lubricated applications, and offer an exceptionally low coefficient of friction, leading to lower friction losses than alternative polymer solutions.
The current 7-speed AT from JATCO is fitted to the Nissan Fairlady Z, Skyline, Fuga, and the Infiniti FX50 and EX37, enhancing the driving pleasure for these luxury rear drive vehicles. The light, compact unit occupies little more space than a 5-speed automatic transmission, while delivering improved fuel efficiency by reducing friction. Its multi-staged gear ratios and increased transmission ratio range offer improved startup and mid-range acceleration, plus enhanced smoothness and quietness at high speeds.
VespelŪ SP-21 thrust washers.
VespelŪ SP-21 thrust washers have been proven for decades in transmissions for cars, buses and agricultural machinery, where they can provide unmatched reliability and durability. Key benefits include:
- No melting point - the washer will not melt.
- High limiting PV value (an indicator of resistance to wear) - superior to other engineering resins.
- Low wear rates - exceptional wear resistance in contact with lubricated aluminum components, even with foreign matter in the oil.
- Custom-designed oil grooves - allow precise control of oil flow, and further enhance resistance to wear.
- Very low coefficient of friction - oil film forms easily on washer surface, leading to low friction losses, low wear, lower heat generation.
- Superior heat resistance - VespelŪ parts can easily handle typical transmission operating temperatures of -40°C to +180°C.
Visit here - http://www2.dupont.com/Vespel/en_US/assets/downloads/energy/Vespel_thrust_washers_in_JATCO_automatic_transmission.pdf to view a PDF of the case study, and visit www.vespel.dupont.com and www.tryvespel.dupont.com for information on how VespelŪ parts can solve your automotive wear, friction or sealing challenges.