Diagnosis & Overhaul - JATCO 3N71B, E4N71B, JM600, L3N71B & L4N71B: Description

JATCO 3N71B and L3N71B transmissions are 3-speed units, consisting of 3-element torque converter and 2 planetary gear sets. The E4N71B and L4N71B are 4-speed units, consisting of 3-element torque converter and 3 planetary gear sets.

The L3N71B and L4N71B models use lock-up type torque converter. Model 3N71B uses conventional type converter. Model L4N71B is based on L4N71B and provides electronic control of converter lock-up in all forward gears.

The E4N71B model uses microcomputer to select shift pattern ("standard" or "power") depending upon rate at which accelerator is depressed. Shift pattern programs are set in lock-up control unit depending upon vehicle speed and throttle position.

To provide friction elements required to obtain desired function of planetary gear sets, 3N71B and L3N71B models utilize 2 multiple disc clutches, 1 multi disc brake, 1 brake band and 1-way clutch. On E4N71B and L4N71B models, multiple disc clutches, 1 multi-disc brake, 2 brake bands and 1-way clutch are used.

On all models, hydraulic system, pressurized by gear-type pump, provides working pressure required to operate friction elements and automatic controls.