The timing system comprises a primary chain operated by the crankshaft ring gear which transmits the power to two intermediate ring gears each of which, in turn, controls a secondary chain that activates the inlet and exhaust camshaft ring gears for the respective bank.The primary chain slides on two fixed guides and a moving guide that acts as a tensioner because it is connected to a hydraulic tensioner.Special oil jets lubricate the moving timing system components.The secondary chains are each guided by a fixed pad and tensioned by a moving pad thrust by a hydraulic tensioner.
Chain, gear and reference assembly for timing system
1. Reference at left inlet camshaft gear for left secondary chain2. Reference at left secondary chain for left inlet camshaft gear3. Reference at left exhaust camshaft gear4. Reference at left secondary chain for left exhaust camshaft gear5. Left secondary chain6. Reference at primary chain for left intermediate gear7. Reference at left intermediate gear for primary chain8. Left intermediate gear9. Reference at left secondary chain for left intermediate gear10. Left intermediate gear window for left secondary chain11. Primary chain12. Reference at primary chain for crankshaft gear13. Reference at crankshaft gear for primary chain14. Crankshaft gear for primary chain15. Right intermediate gear16. Reference at primary chain for right intermediate gear17. Reference at right intermediate gear for primary chain18. Reference/window at right intermediate gear for right secondary chain19. Reference at right secondary chain for right intermediate gear20. Right secondary chain21. Reference at right exhaust camshaft gear for right secondary chain22. Reference at right secondary chain for right exhaust camshaft gear23. Reference at right secondary chain for right inlet camshaft gear24. Reference at right inlet camshaft gear for right secondary chain
Timing system crankshaft gear
The gear fitted on the crankshaft has the function of transmitting power from the crankshaft to the timing system kinematic chain; it has inverted teeth and works on the main timing chain which also has inverted teeth.
1. Main chain teeth2. Crankshaft internal matching surface3. Housing for key
Camshaft drive gears
The four camshaft drive gears, with the rear view (camshaft side) and the front view (timing side) for the individual gear illustrated in the diagram, incorporate the hydraulic actuators that allow the timing of the four camshafts (two inlet and two exhaust) to be varied continuously.
The two intermediate gears have the task of receiving the drive from the crankshaft by means of the primary timing chain and transmitting it to the camshaft drive gears by means of the secondary timing chain.There are two toothed ring gears to carry out this function; the larger ring gear has inverted teeth and works on the primary timing chain (which also has inverted teeth), whilst the smaller ring gear has normal teeth and works on the secondary timing chain.
1. Main chain teeth2. Bearing cover surface3. Fixing bolt housing surface4. Crankcase side bearing cover surface5. Secondary chain teeth
Timing drive chains
The primary drive chain is made with inverted teeth and the gear on the crankshaft also has inverted teeth; the intermediate gear has inverted teeth for connection with the primary chain and a coil with standard teeth for connection with the standard type secondary chain.
A. Secondary chainB. Primary chain1. Rollers2. Mesh3. pins4. Inner meshThe timing chains have the task of transmitting the power between the various timing gears; they also have timing reference markings on the outer mesh.
Hydraulic tensioners
All the hydraulic tensioners are fitted on the crankcase or the head with a gasket in between that has the task of keeping an oil reserve inside the tensioner to ensure correct operation during starting.Primary chain hydraulic tensioner
