Clutch Released 1 Clutch housing 2 Clutch discs separated 3 Clutch apply pressure port (no pressure) 4 Apply piston When no clutch apply pressure is applied to the piston, the springs hold the piston away from the plates. This prevents the plates from meshing together and allows them to rotate freely with no drive transmitted from the hub to the housing. Clutch Applied 1 Clutch apply pressurised fluid 2 Apply piston 3 Clutch discs forced together 4 Clutch apply pressure port (Apply pressure present) M44 1771 2 3 4 1 M44 1772 4 3 1 2
AUTOMATIC TRANSMISSION – GM LE DESCRIPTION AND OPERATION When hydraulic apply pressure from the applicable shift valve is initially applied to the piston, the pressure overcomes the spring force and moves the piston into contact with the plates. This initial movement takes up any clearance between the plates. As the pressure behind the piston rapidly increases, the rapid pressure rise is damped by the appropriate accumulator, allowing the piston to apply force to the plates gradually. This provides a smoother clutch take up. With the plates meshed together, the housing can now be driven with the hub or the hub can beheld stationary.