Slider Crank Mechanism

Slider Crank Mechanism. MAYURESH DHOTRE ANUJ DHUMAL DIPTI DHURI PRANAV DIKONDA DURVANK DEWALE.

INTRODUCTION. slider crank mechanism, arrangement of mechanical parts designed to convert straight-line motion to rotary motion, as in a reciprocating piston engine, or to convert rotary motion to straight-line motion, as in a reciprocating piston pump. A slider-crank linkage is a four-link mechanism with three revolute joints and one prismatic, or sliding, joint.The rotation of the crank drives the linear movement the slider, or the expansion of gases against a sliding piston in a cylinder can drive the rotation of the crank. Slider-crank chain inversion arises when the connecting rod, or coupler, of a slider-crank linkage becomes the ground link, so the slider is connected directly to the crank. This inverted slider-crank is the form of a slider-crank linkage that is often used to actuate a hinged joint in construction equipment like a crane or backhoe, as well as to open and close a swinging gate or door..

There are two types of slider-cranks:. In – line : An in-line slider-crank has its slider positioned so the line of travel of the hinged joint of the slider passes through the base joint of the crank. This creates a symmetric slider movement back and forth as the crank rotates. Offset : If the line of travel of the hinged joint of the slider does not pass through the base pivot of the crank, the slider movement is not symmetric. It moves faster in one direction than the other. This is called a quick-return mechanism..

WORKING PRINCIPLE. A slider-crank is a four-bar linkage that has a crank that rotates coupled to a slider that the moves along a straight line. This mechanism is composed of three important parts: CRANK SLIDER CONNECTING ROD.

As the slider moves to the right the connecting rod pushes the wheel round for the first 180 degrees of wheel rotation. When the slider begins to move back into the tube, the connecting rod pulls the wheel round to complete the rotation..

Different mechanism by fixing different link of slider crank chain are as follows : First inversion This inversion is obtained when link 1 (ground body) is fixed. Application- Reciprocating engine, Reciprocating compressor etc. Second inversion This inversion is obtained when link 2 (crank) is fixed. Application- Whitworth quick return mechanism, Rotary engine, etc. Third inversion This inversion is obtained when link 3 (connecting rod) is fixed. Application- Slotted crank mechanism, Oscillatory engine etc. Fourth inversion This inversion is obtained when link 4 (slider) is fixed. Application- Hand pump, pendulum pump or Bull engine, etc..

0497 95.74• 93.74' 04. . Inverted slider crank mechanism.

ADVANTAGES. Low cost Reduced number of parts Reduced weight Less wear and clearance.

DISADVANTAGES. When the crank is driven by the connecting rod, a problem arises when the crank is at top dead centre (0°) or bottom dead centre (180°). At these points in the crank's cycle, a force on the connecting rod causes no torque on the crank. Therefore if the crank is stationary and happens to be at one of these two points, it cannot be started moving by the connecting rod. For this reason, in steam locomotives, whose wheels are driven by cranks, the connecting rods are attached to the wheels at points separated by some angle, so that regardless of the position of the wheels when the engine starts, at least one connecting rod will be able to exert torque to start the train..

APPLICATION. Reciprocating Engines/Pumps : The slider-crank mechanism which converts straight-line motion to rotary motion and vice-versa, this principle is used in reciprocating engines/pumps. Combustion Engines : Slider-crank mechanism is used in piston cylinder assembly in combustion engines and converts reciprocating motion into circular motion and vice-versa. Rotary Engines : Fixing the crank in the Slider-crank mechanism it can be used to form rotary engines. Rotary engines are used in cars. Oscillating cylinder Engine : Fixing the connecting rod in the Slider-crank mechanism it can be used to form oscillating cylinder engines. Hand Pump : Fixing the slider in the Slider-crank mechanism it is use to form hand pumps..

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