What is SU Carburetor?

Here is the complete guide about SU Carburetor. Here we provides SU Carburetor working principle, types and Advantages ect.

SU carburetor is an example of a constant vacuum type of carburetor. It consists of a single jet in which a tapered needle operates. The area of the throat is varied by means of a piston which slides up and down. The tapered needle is connected to the accelerator.

SU carburetor full form is Skinners Union carburetor. Skinners Union is a carburetor company established in London in 1910. SU carburetor is a constant depression or constant vacuum type of carburetor. It has an automatic variable choke rather than a simple choke.

SU Carburetor

SU carburetor full form is Skinners Union carburetor. Skinners Union is a carburetor company established in London in 1910. SU carburetor is a constant depression or constant vacuum type of carburetor. It has an automatic variable choke rather than a simple choke. We are going to see the construction and working of SU carburetor which completely different from the choke type carburetor.

Working of SU carburetor:

  • SU carburetor consists of a float chamber, piston, piston rod, piston rod guide, helical spring, suction disc, suction chamber, accelerator, taper jet needle, and jet.
  • A suction disc is nothing but a flat portion above the piston. A piston rod is connected to the taper jet needle at rock bottom side. Taper jet needle is inserted into the most jet which is connected to the float chamber. The up and down movement of the piston and piston rod controls the air duct .
  • The air duct is connected is to the air chamber with the assistance of suction air entrance as shown within the figure. The suction chamber is situated above the suction disc. An air rectifier hole is used to provide atmospheric air to the suction disc.
  • The air-fuel ratio within the SU carburetor is controlled by the up and down movement of the piston.
  • Pressure within the suction chamber is directly proportioning to the opening of a butterfly type accelerator whereas the pressure at suction disc is atmospheric.
  • SU carburetor contains just one jet. there’s no separate acceleration pump or an idling jet-like Solex carburetor and Carter carburetor.

Starting of SU carburetor:

  • At the time of starting the engine, an upscale mixture of air and fuel is extremely important. This mixture are often obtained by pulling the jet during a downward direction with the assistance of a lever. Opened accelerator allows more air to flow under more suction causes the piston moves upward direction and increases the jet area in SU carburetor.
  • This increased jet area allows more engine fuel to flow into the mainstream. Therefore, within the SU carburetor, a continuing air-fuel ratio maintained at different engine speeds, unlike other modern carburetors.

Types of SU Carburetor

SU carburettors were provided in several “throat sizes” in both inch and millimetre measurement. These carburetors are identified by letter prefix which indicates the float type. “H”, “HD”, “HS”, “HIF”, “HV”, “OM” and “KIF”.

“H” types have float bowl with an arm cast into its base. it’s mounted to rock bottom of the carburetor with a hollow bolt. Fuel passes in carburetor body through the arm. “HD” it’s the float bowl with its arm fastening directly below, and concentric with the jet. The arm features a flange that tightened with four screws at rock bottom of carburetor. A sealed rubber diaphragm is integral with the jet. “HS” the most body is roofed with rubber, fuel is supplied by an external pipe to the jet.

“HIF” it’s horizontal Integral Float. “HV”, “OM” and “KIF” types less commonly used.

Vehicles using SU carburetor:

SU carburetor is another type of modern carburetor that is widely used in Bentley, Austin, Jaguar, Rover, Rolls-Royce, Saab automobiles and Volvo.

Advantages

The main advantage of SU carburetor is that the rapid response during accelerating. Hence it’s fitted with racing cars and in most of the scooters and motorcycle.

SU Carburetors were widely utilized in automobile vehicles from much of the 20 th century. These also are utilized in aircraft engines including the first versions of the Rolls Royce.

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