3.0 TDI V6 S line Plus SUV
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£8,200
- Year/Month: 2013/0
- Stock ID: T119820
- Transmission: Automatic
- CC: 3000
- Mileage: 218693
- Fuel Type: Diesel
- 285 Views
The camshaft in Audi q7 automatic for sale is usually positioned in the head (single-shaft distribution) and is driven by the crankshaft to which it is connected by a chain or belt and with respect to which it rotates in synchronous. Depending on the number of valves per cylinder and the arrangement of the cylinders, there may be more camshafts, but usually, there are two per bank (double overhead camshaft), in this case, we refer to a double shaft distribution, typical of high-performance engines. The profile of the cams is characterized by an eccentricity, which can be more or less elevated and which is called the lift.
Possible To Adjust
By modifying the timing by means of a special variator, it is possible to adjust the valve opening time and therefore the filling of the combustion chamber, optimizing performance or consumption. Increasing the opening time results in an increase in power and torque, while with the variation in the discharge phase, the phase in which the intake and exhaust valves are open simultaneously can be extended so that the unburned gases are expelled thanks to at the entrance of the new mixture, thus keeping the combustion chamber clean. The arrangement of the valves is rather diversified from engine to engine in terms of positioning inside the combustion chamber. The control of the valves, on the other hand, can take place substantially through two methods, which are distinguished according to the positioning of the camshaft.Â
With Overhead
Please note, there can be engines with camshafts in the crankcase and others with overhead camshafts. The qualitative differences between the two solutions may appear clearer if the systems are analyzed individually. The engine with camshaft positioned in the crankcase usually appears in the configuration with rods and rocker arms. This means that in order to be able to pilot the valves that are housed in the head, these engines necessarily need a series of levers capable of transforming the rotary motion of the camshaft, and therefore of the eccentric, into the alternating rectilinear motion of the valves. Hence, a used car buyer should check the quality of the discussed parts to avail a reasonable Audi q7 automatic price. Besides, a typical distribution with rods and rocker arms consists of the following parts such as camshaft, tappets, rods, adjusting screws, rocker arms, springs and valves.Â
To Control Inertia
The disadvantage of this system is the greater mass of the organs involved. Also, take into account the fact that in any case, the spring load should be such as to be able to overcome the inertia of all the components in alternating motion. This means that in the case of rod and rocker motors there is a waste of power also because it is necessary to compress springs with higher elastic stiffness. the spring load increases as the masses with alternating motion, the number of revolutions and also the rise increase respectively. These are the reasons why in general the rod and rocker motors do not reach high rotation speeds. That being said, the enormous and not negligible advantage of being able to remove the head without touching the timing of the distribution remains in favor of the distribution by means of rods and bi-rollers. This is thanks to the fact that in the solution to rods and rocker arms the connection between the motor shaft and the camshaft does not involve the head.
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