D. Total Operation USA Starting Model Year 1981
OPERATION EXHAUST GAS RECIRCULATIOND. Total operation USA starting model year 1981
EGR begins above approx. 40 °C/104 °F coolant temperature after free travel of free travel rod is eliminated, EGR takes place in total partial load range.
Starting at a coolant temperature of approx. 40°C / 104°F the thermovalve (36) opens. The vacuum, at idle 350-500 mbar, moves to switchover valve (64a(.
If the control linkage is at idle speed stop, the EGR valve (60) is vented externally. There is no EGR.
If the throttle linkage is opened so that the free travel in the free travel rod is eliminated, the switchover valve (64a) is switched over by the cam of guide lever (68). The vacuum now moves via the two switchover valves (64a and 64b) to EGR valve and opens the valve completely. This results in max. possible EGR.
At increasing load, the vacuum is gradually decreased via vacuum control valve (65). This also reduces the amount of recirculated exhaust gas. Shortly before reaching full load position, the switchover valve (64b) is vented to atmosphere via the cam of guide lever (68). The vacuum is completely removed, there will be no EGR.