Dugald Clerk developed the first two cycle engine in 1879. It used a separate cylinder which functioned as a pump in order to transfer the fuel mixture to the cylinder.6
In 1899 John Day simplified Clerk's design into the type of 2 cycle engine that is very widely used today.13 Day cycle engines are crankcase scavenged and port timed. The crankcase and the part of the cylinder below the exhaust port is used as a pump. The operation of the Day cycle engine begins when the crankshaft is turned so that the piston moves from BDC upward (toward the head) creating a vacuum in the crankcase/cylinder area. The carburetor then feeds the fuel mixture into the crankcase through a reed valve or a rotary disk valve (driven by the engine). There are cast in ducts from the crankcase to the port in the cylinder to provide for intake and another from the exhausst port to the exhaust pipe. The height of the port in relationship to the length of the cylinder is called the "port timing."
On the first upstroke of the engine there would be no fuel inducted into the cylinder as the crankcase was empty. On the downstroke the piston now compresses the fuel mix, which has lubricated the piston in the cylinder and the bearings due to the fuel mix having oil added to it. As the piston moves downward is first uncovers the exhaust, but on the first stroke there is no burnt fuel to exhaust. As the piston moves downward further, it uncovers the intake port which has a duct that runs to the crankcase. Since the fuel mix in the crankcase is under pressure the mix moves through the duct and into the cylinder.
Because there is no obstruction in the cylinder of the fuel to move directly out of the exhaust port prior to the piston rising far enough to close the port, early engines used a high domed piston to slow down the flow of fuel. Later the fuel was "resonated" back into the cylinder using an expansion chamber design. When the piston rose close to TDC a spark ignites the fuel. As the piston is driven downward with power it first uncovers the exhaust port where the burned fuel is expelled under high pressure and then the intake port where the process has been completed and will keep repeating.
Later engines used a type of porting devised by the Deutz company to improve performance. It was called the Schnurle Reverse Flow system. DKW licensed this design for all their motorcycles. Their DKW RT 125 was one of the first motor vehicles to achieve over 100 mpg as a result.14
What to buy a gift for fans of the automotive industry?
Buying a gift can be a problem, especially if we want to make a gift without obligation, but still quite meaty and really interesting for the recipient. What buy a fan of the automotive industry? Certainly a nice gift idea for such a person is choosing a book in this field. However, one should check if the person you want to give away no longer has such a home. Available on the market, however, is much different proposals in this regard, that will certainly find something suitable, as well as inexpensive. The book is a very good gift idea for people of all ages, and entered at the start of commemorative dedication certainly will constitute a kind of souvenir. So let's decide on the choice of books, if you are looking for an idea for a gift for a fan of the automotive industry.
Driving the bus
Buses are one of the most important means of communication. Thanks to them we can quickly get to a certain place without thinking about parking and so on. To become a bus driver it is necessary to invest in a special driver's license. Although at this rate it differs significantly from the "normal" driving license, license for driving cars, if only because of the size of the vehicle, which we, however, provides a number of people interesting experiences. Driving license this category is much less common than the traditional license category B, so that we can greatly increase your chances for example in the labor market, when put in their application documents mention of such a document.