F2B ENGINE 113 T RAKKER E URO 4/5 Print 603.93.641 Base q November 2006 Actuator Figure 223 71834 1. Air inlet - 2. Gasket - 3. Piston - 4. External spring - 5. Internal spring control disc - 6. Internal spring - 7. O-ring - 8. Spring holder - 9. Limit stop - 10. Dust seal - 11. Control rod Figure 224 [bar] Stroke [mm] 72421 a Gradient characterized by the effect oftheexternal spring (4, Figure 223). b Gradient characterized by the effect of the external (4, Figure 223) and internal (6) springs.
Working principle (See Figure 223) The actuator piston, connected to thedrive rod, is controlled with the compressed air introduced through the air inlet (1) on the top of the actuator. Modulating the air pressure varies the movement of the piston and turbine control rod. As the piston moves, it progressively compresses the external spring (4) until the base ofthe piston reaches the disc (5) controlling the internal spring (6). On further increasing thepressure, thepiston,via the disc (5), interferes with the bottom limit stop (10).
Using two springs makes it possible to vary the ratio between thepiston strokeand the pressure.Approximately 85%ofthe stroke of the rod is opposed by the external spring and 15% by the internal one. Solenoid valve for VGT control This N.C. proportional solenoid valve is located on the left-hand side of the crankcase under the turbine. The electronic control unit, via a PWM signal, controls the solenoid valve, governing the supply pressure of the turbine actuator, which, on changing its position, modifies the cross-section of the flow of exhaust gases onto the blades of the impeller and therefore its speed. The resistance of the coil is approx. 20-30 Ohms.
REPAIRING ACTIONS NOTE If anomalous engine operation is found, which is due to the boosting system, it is advisable that you check the efficiency of seal gaskets and the fastening of connecting sleeves prior to carrying out the checks on the turboblower. Also check for obstructions in the sucking sleeves, air filter. If the turbocharger damage is due to a lack of lubrication, check that the oil circulation pipes are not damaged. If so, change them or eliminate the cause. After carrying out the above mentioned checks, check the turbocharger operation with an Engine Test by using IVECO diagnosis equipment (Modus - IT 2000 - E.A.SY.) according to the relevant procedure.
NOTE The test must beperformedin following conditions: - engine coolant temperature >50 ºC; - battery up (voltage >22V) for compression test; - efficient recharging system. If values beyond tolerance are detected, check the efficiency of: - shut-off valve; - pressure sensor; - engine cable pressure sensor connection (if oxidised, clean with a specific product); - lack of electrical defects in solen oid valve VGT (continuity connection); - actuator moved by active diagnosis as described in relating chapter, in case of locking, grease bushing with lubricant Kernite (for high temperatures); if the trouble persists, replace the actuator; - sliding sleeve:
it must slide freely when operated manually. If locked and if the bush check is not sufficient or effective, or no faults are detected in the other points, upon authorization ofthe yHelp Desky market operator, change the turbocharger according to the standard procedures.