When an automatic transmission fails, more often than not the problem can be traced to the clutch plates. Why does an automatic transmission have a clutch and how does it work? Is there differences in steel clutch plates and if so, what are they?
Why use clutch plates?
It’s simple, without them the vehicle would go nowhere. Steel clutch plates and clutch bands are those components that assist the transmission of power in a controlled fashion. They are applied gradually as the vehicle engine speed increases; this gradual application of pressure softens the provision of power to the drive shaft, rear end and wheels.
Clutch plates are normally made from very durable but quite thin steel. Once they have been stamped out and de-burred they are coated with a special material that allows them to “bite” but not to the point where they would wear out prematurely. The assembly is quite complex, the clutch plates are mounted in a drum, the assembly method is one plate, one disc, one plate, one disc etc until the correct assembly is completed. The number of disc/plate assemblies depends on the automatic transmission design.
Pressure, which is applied via hydraulics, is used to compress the disks and steel clutch plates causing the special material to grip. The drum and center shaft turn independently until pressure is applied by the hydraulic pistons.
Failure:
When the automatic transmission fails it cause is often the discs. Once the small grooves in the disc surface are gone, the discs must be replaced. When the discs fail, in other words when they no longer engaging the transmission, it is steel clutch plate against steel clutch plate, the transmission will simply slip without any friction material between the plates. It is imperative that repairs be carried out quickly as metal could be shaved from the plates resulting in total transmission failure.
Raybestos Powertrain is one of the largest distributors of transmission-related friction products in the world. Get in touch with them.
