Functional explanation
　In 4 cycle engines and 2 cycle engines, as for method of being effective the engine brake being different it is thought that method of consenting it is many, but before explaining “with crankcase internal pressure control valve”, just we would like to touch a little concerning the phenomenon where the engine brake of 2 cycle engines is weak. With inhalation process of 2 cycles the occasion where the piston moves to top dead center, from the carburetor the fuel and the air when in the crankcase gathering and falling, passing by the air-supplied port, it is sent by the combustion chamber, being compressed burns, it continues by the fact that process is repeated and turns. Namely, when the accelerator is closed, the fuel and the air in the crank case mean not to be sent. Therefore in the crank case or, the air which it should compress does not exist (only it is in the combustion chamber) for the sake of the engine brake (compression resistance) is a little weak. Vis-a-vis this, the crankcase of 4 cycle engines through the breather pipe, has led inside air and [eakurinabotsukusu], because always the air exists inside the case, resetting the throttle in the same way as 2 cycles, the air inside the case being compressed, this resistance becomes the engine brake. When you rephrase, the engine brake already exists from at the time of engine starting, the inside of travelling pushing away the engine brake, means to advance. Therefore, maintaining the crankcase internal pressure low brings friction decrease, running becomes good, the vibration decreases, the merit such that fuel economy becomes good is borne.
  The engine where the internal pressure is easy to rise, like L type and V type etc as seen in type and 360 degree twin and the boxer etc which share one crankcase, it becomes the engine and the like where 2 pistons move to the same direction simultaneously. When the bore it raised the small aerodynamic volume displacement with the single engine and the like, being pressured resistance of the amount where the piston area increased (Pascal's principle) joins, furthermore becomes the engine whose revolution rise is slow. This phenomenon appears becoming the phenomenon where the pickup of the class where the aerodynamic volume displacement is large even with the similar type engine is sluggish. One more in the same way, in the engine and the engine of separation oil supply type of mission, the amount where air volume of the mission part which it can utilize as the saucer of compression to that is gone, furthermore this phenomenon appears remarkably, when 200 - 500 revolutions and idling revolution rises depending upon the type it is.
  Actually, great pressure, it is the kind of phenomenon which cannot be thought, but isn't probably that either the people who the phenomenon where the engine becomes heavy depending upon the oil level which was inserted at the time of motor oil exchange too much, bodily sensation are done are not few? In addition, also those where the response feels well when the oil level immediately before the exchanging has decreased are the same phenomenon. This way if it tries thinking, it understands that it is influenced by very little air volume.

  It is the device to which action of the [buroohu] valve, being proportionate to speed, when resetting the throttle to the occasion where you use the engine brake at control and the high-speed travelling time of the BOX internal pressure which to excessively becomes high, lets escape the BOX internal pressure which rises in the highest pressure, maintains at optimum state. Therefore, there is no merit which is installed other than the RAM pressure specification vehicle.
The state of STD
 In the blow-by pipe the penetration prevention valve (in this case, the crankcase internal pressure control valve) when it is not, during high-speed travelling the pressure which loses the destination when the throttle is closed, as for rising the crankcase internal pressure easily is not difficult in the imagination.
  When this is analyzed, throttle off -> travelling wind pressure loses the destination, -> penetration -> [enbure] becomes hard inside the crankcase, -> deceleration -> revolution -> start of acceleration -> the inside of the crankcase becomes decompression -> the Don attachment, with. Namely the internal pressure which held down the revolution of the engine mandatorily starting turning with throttle Xu opening because it is discharged, the engine selfishly, the Don attachment is induced. It is not the skill which can form the power which is abundant never.
  In the same way also the combustion chamber, about the engine which is tuned high-level dislikes excessive supply. As a concrete harmful influence, other than the aforementioned throttle turning off if road intersection method is observed, when the speed which is not problem” is exceeded”, also combustion chamber pressure rising simultaneously with crankcase internal pressure rise, abnormal combustion (detonation) it becomes easy to induce the trouble which it occurs. In the world of race/lace about the engine which is proud of high output with the bench, with actual travelling to handle it changes to the engine quality where setting is difficult to come out difficult. When (with the low gear the engine turns with high revolution, it is not this limit. )
  When another expression is done, the pneumatics which record high output with the bench (atmospheric pressure) under condition other than, 0 element becomes many. When turbo pressure is taken as example, as for the engine which increased pressure too much because high output cannot be obtained, the [uesutogeto] valve which lets escape surplus pressure is used. The compression ratio which is too high and, the charging efficiency which is too high it becomes conversely compression resistance.
  When resetting the throttle, there is a type which uses the mechanism where the RAM duct passage is cut off is closed in the opposite car, but with complete airtightness structure even idling of the engine the passage is cut off with imperfect state because it becomes impossible, by all means. As a result, the pressure which creeps in from the opening causes crankcase internal pressure rise in the same way and causes trouble.
  When the viewpoint is changed, if it is the usual wave which occurs in the sea, it can make pass to go, but it prevents the external pressure which does not have during the being cut off like the tidal wave the way it is not. For example because the passage is closed, not to be, portion of the passage (example: Portion and the like of the bottom of conduit) being raised, when the passage is closed, you can say that the one where the open part which is discharged to air simultaneously appears is desirable. … In state of the highest speed as for the same hand it means not to be able to use.
  As for the back torque limiter by the fact that intense torque is cut off, easing the engine brake, as for problem such as fundamental quality and fuel economy of engine side it cannot solve. Lastly, as the pressurizer without considering RAM SYSTEM, it decreases inhalation resistance and as the expedient which increases charging efficiency the one which is considered it can obtain gentler engine quality. Because by the way, RAM bodily sensation is possible even speed per hour 40Km/h.