The material most used in the manufacture of culassas es aluminum alloys are relatively easy to work, light and good thermal conductivity. The engines used mainly old cast iron.
As aluminum has poor surface quality, it is necessary to provide the culassa several false in order to improve their strength and longevity. The most important are those of the valve seatmade of high strength steel to resist coke out (at the time of closing) in the difficult conditions of high temperature and reactive gases (escape).
With the introduction of unleaded gasoline were lost, the lubricating properties of this element, so that the valve seats projected to run on this fuel had to be even tougher. Other inserts may be the guides of the valves, supports the camshaft and rocker arms and screw the candle, although some of these may be machined directly on the aluminum culassa. The indirect injection diesel engines still have the pre-combustion chamber as fake.
There are engines in the engine block and culassa are merged on the same piece. With this can save up to n'vel production (fewer parts to manufacture and mount), but still has the advantage of providing a lower emission hidrocarbonetosnão burned.
Culassa in the grip of the cylinder can be used screws, but the use of bolts is most common. The force (torque) and the order of tightening is recommended by manufacturers, in order to avoid permanent deformation when the culassa opreração assembly. Before the 80 "run" the engine that allowed the different parts are accommodated each other, which meant that the strain of tightening culassa forced to downsize and tighten their after 500 miles. Currently bolts are manufactured in a material with uni limit lending, with control of its elongation extremely sophisticated. Thus, it becomes unnecessary to tighten, because the settings of several pieces during the filming signitificativamente are lower than the initial elongation of the bolts
No comments:
Post a Comment