GROUP MEMBER  Muhammad Abbas Akram (15-ME-50)  Leeman Hussain (15-ME-54)  Naveed Iqbal (15-ME-51)  Muhammad Bilal Ali (15-ME-49)  Hafiz Abubakar (15-ME-48) Swedish college of engineering and technology Rahim yar khan

SLIDER CRANK MECHANISM  Modification of the four bar chain  It consist of one sliding pair and three turning pairs.  Reciprocating steam engine mechanism.  Mechanism converts rotary motion into reciprocating motion and vice versa. Swedish college of engineering and technology Rahim yar khan

SLIDER CRANK ANIMATION Swedish college of engineering and technology Rahim yar khan

SLIDER CRANK MECHANISM  In a single slider crank chain, as shown in Fig. the links 1 and 2, links 2 and 3, and links 3 and 4 form three turning pairs while the links 4 and 1 form a sliding pair.  The link 1 corresponds to the frame of the engine, which is fixed. The link 2 corresponds to the crank ; link 3 corresponds to the connecting rod and link 4 corresponds to cross-head. As the crank rotates, the cross-head reciprocates in the guides and thus the piston reciprocates in the cylinder Swedish college of engineering and technology Rahim yar khan

THE MECHANISM HAS A STROKE B 1 B 2 EQUAL TWICE THE CRANK LENGTH R 2. LOCATIONS B 1 AND B 2 ARE CALLED THE EXTREME POSITIONS (LIMITING) OF THE SLIDER Swedish college of engineering and technology Rahim yar khan Slider-Crank Mechanism

THE SLIDER-CRANK MECHANISM Swedish college of engineering and technology Rahim yar khan

HELICAL GEAR Swedish college of engineering and technology Rahim yar khan Key points: Teeth cut on helical gear at an angle to the face of the gear This gradually engagement make helical gear operate more smoothly and quietly One Two such gears may be used to connect two parallel shafts in place of spur gears. The helixes may be right handed on one gear and left handed on the other. The teeth of helical gears with parallel axis have line contact, as in spur gearing. This provides gradual engagement and continuous contact of the engaging teeth

HELICAL GEAR Swedish college of engineering and technology Rahim yar khan Proportions for helical gears Though the proportions for helical gears are not standardized, yet the following are recommended by American Gear Manufacturer's Association (AGMA). Pressure angle in the plane of rotation, φ = 15° to 25° Helix angle, α = 20° to 45° Addendum = 0.8 m (Maximum) Dedendum = 1 m (Minimum) Minimum total depth = 1.8 m Minimum clearance = 0.2 m Thickness of tooth = m

FORCES COMPONENTS ON A TOOTH OF HELICAL GEAR Swedish college of engineering and technology Rahim yar khan In order to have more than one pair of teeth in contact, the tooth displacement (i.e. the advancement of one end of tooth over the other end) or overlap should be at least equal to the axial pitch, such that Overlap = p c = b tan α... tangential component (W T ) and the other axial component (W A ), W A = W N sin α = W T tan α

BEVEL GEAR Swedish college of engineering and technology Rahim yar khan Definition: When two non parallel and coplanar shaft are connected by gear these gears are called bevel gear

Swedish college of engineering and technology Rahim yar khan

Swedish college of engineering and technology Rahim yar khan

WORM GEAR Swedish college of engineering and technology Rahim yar khan Definition: A worm drive is a gear arrangement in which a worm (which is a gear in the form of a screw) meshes with a worm gear(which is similar in appearance to a spur gear). The two elements are also called the worm screw and worm wheel. The terminology is often confused by imprecise use of the term worm gear to refer to the worm, the worm gear, or the worm drive as a unit.gear arrangementscrewspur gearelements

Design of worm gearing system 1.Lead angle of the worm λ = Lead angle of the worm. We know that tan λ = m n/D w 1.Velocity ratio V.R. = T G / n 2.Centre distance D G = m.T G x = D G + D W 3.Efficiency of the worm gearing η =tan λ (cos φ - μ tan λ )/(cosφ tan λ + μ ) Wear tooth load for worm gears The limiting or maximum load for wear (W W ) is given by W W = D G. where D G = Pitch circle diameter of the worm gear, b = Face width of the worm gear, and K = Load stress factor (also known as material combination factor). The load stress factor depends upon the combination of materials used for the worm and worm gear

Swedish college of engineering and technology Rahim yar khan