3.-Pegas-Edited2
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SPRING (PEGAS)
Pegas dapat digolongkan atas dasar jenis beban yang dapat diterimanya yaitu :• Pegas Tekan• Pegas Tarik• Pegas PuntirSedangkan jika dipandang dari segi bentuk, maka pegas dapat dibedakan menjadi lima bagian, yaitu :o Pegas Voluto Pegas Dauno Pegas Piringo Pegas Cincino Pegas Batang Puntiro Pegas Spiral atau Pegas jam
KLASIFIKASI PEGAS
Types of springs
1. Helical springs2. Conical and volute springs3. Torsion springs4. Laminated or leaf springs5. Disc or bellevile springs
1. Helical Spring
A helical spring is made up of a wire coiled in the form a helix
- Circular- Square- Rectangular-Compression helical springs
-Tension helical spring
Helical Springs Closely Coiled HS
Open Coiled HS
1. Helical Spring
1.Fungsi : a. Menyimpan gaya yang selanjutnya dikonversikan menjadi energib. Peredam
2. Penggunaan : a. Persenjataanb. Sistem suspensic. Pembatasan Gaya (pada pengepresan)
Compression Spring (Pegas Tekan)
Pegas Tarik (Tensile Spring)
1.Fungsi : a. Penyiman gayab. Penyimbang
2. Penggunaan : a. Timbanganb. Standrtc. Tromol
1. Helical Spring
2. Pegas Kerucut (Volute Spring & Conical spring)
1.Fungsi : a. Memberi reaksi dan mengatur tekanan
2. Penggunaan : a. Penutup cup mobileb. Pembersi kaca di mobil
2. Pegas Kerucut (Volute Spring & Conical spring)
Conical Spring
Volute Spring
2. Pegas Kerucut (Volute Spring & Conical spring)
The characteristic of volute / conical spring is sometimes utilised in vibration problems where springs are used to support a body that has a varying mass.
1.Fungsi : a. Menerima beban dan memberi reaksi puntiranb. Penyeimbangc. Suspensi
2. Penggunaan : a. Handle mobilb. Penjepit
3. Torsion Springs
1. Helical Torsion Spring
2. Spiral torsion spring
3. Torsion Springs
Helical Torsion Spring
Spiral Torsion Spring
The Analysis of Compression Springs
1. Solid Length When the coils contact with each other2. Free Length The normal condition of compression springs3. Spring Index Ratio of mean diameter of the coil & the diameter of the wire4. Spring Rate The load required per unit deflection of the spring5. Pitch the axial distance between adjacent coils in uncompressed state. (P)
Equilibrium under the action of two forces (W) and the Twisting moment (T)
D = Mean diameter of the spring coild = Diameter of the spring wiren = Number of active coilsG = Modulus of rigidity for the spring materialW = Axial load on the spring fs = Shear stress induced in the wire due to the twisting momentC = Spring index = D/dp = Pitch of the coilsδ = Deflection of the spring, as a result of an axial load.
Ot only shear stress induced in the wire, the following stresses also act on the wire :1. Direct shear stress due to the load W2. Stress due to curvature of wire.
The Analysis of Compression Springs
The Analysis of Compression Springs
The direct stress due to the load W = Load / Cross-sctional area of the wire
The maximum shear stress
Substituting D/d=C
- Direct Shear- Curvature of the
wire
A shear stress factor (K) / Wahl Stress factor
The effect
Dimana K yaitu :
The Analysis of Compression Springs
The values of K for a given index C
Wahl’s stress factor oncreases very rapidly as the spring index decreases. In machinery the mostly used spring index above 3.
The Analysis of Compression Springs
The standard size of the spring wire may be selected from the following table
The Type of End Connections for Helical Springs
Plain ends
Ground ends
Squared ends
Squared & Ground ends
The Characteristic of End Connections for Helical Springs
1. Inactive Coils The part of the coil which is in contact with the seat does not contribute to spring action.
2. Active Turns The part of the springs that action.
The Connections of Tensile for Helical Springs
- Large stress concentration is produced at this point.
- Attaching device of tension spring
The Connections of Tensile for Helical Springs
A Compression Spring Tensile Spring
Deflection of helical springs of circular wire
Axial deflection of spring
Spring Rate / Stiffness of the Spring
Constant
Energy stored in helical springs of circular wire
Asumtion load is applied gradually
V = Volume of the spring wire
If : P = loadh = height
Stress and deflection in helical springs of non-circular wire
Helical Torsion Springs
- The ends are shaped to transmiit torque.- Bending stress- The radius of curvature of the coils
changes when the twisting moment is applied
Bending Stress
Total Angle of Twist /
Angular Deflection
Deflection
Flat SpiralSprings
Long thin strip of elastic material wound like a spiral.- Watches - Gramaphone
Since the radius of curvature of every spiral decreases when the spring is wound up, therefore the material of the spring is in a state of pure bending.
Flat SpiralSprings
Bending Moment
B at max distance from the application of P Bending Moment Max
Maximum bending stress
Deflection (angular) Asumtion : both ends of the spring are clamped
Deflection
Strain energy
stored in the spring
4. Pegas Daun / Leaf Spring (laminated or carriage spring)
Application :For heavy vehicles, they have the advantage of spreading the load more widely over the vehicle's chassis, whereas coil springs transfer it to a single point.Thereby saving cost and weight in a simple live axle rear suspension.
4. Pegas Daun / Leaf Spring (laminated or carriage spring ) Flat spring
Deflection :
4. Pegas Daun / Leaf Spring (laminated or carriage spring )
Bending Stress Full length
graduated
Nipping Equalised Stress
Stress in full length = 50% Stress in graduated
Should be equal
The Steps :1. Making full length smaller thickness than the graduated leaves.2. Given greater radius of curvature to the full length than graduated.
4. Pegas Daun / Leaf Spring (laminated or carriage spring )
Nipping The Value of initial Gap (Nip C)
The Load on the clip bolt Wb
Final Stress = Stress in the full length due to applied load minus the initial stress
1. The final stress equal to graduated due to applied load plus initial stress.2. The deflection due to applied load is same as without initial stress
4. Pegas Daun / Leaf Spring (laminated or carriage spring )
The lenght of the leaf spring leaves
The effective
Band is used
U-Bolts is Used
The length of leaves
Smallest leaf
Next leaf
Length of (n-1)th leaf
4. Pegas Daun / Leaf Spring (laminated or carriage spring )
Length of master leaf d = diameter of eyet = thickness of master leaf
Standart sizes of automobile suspension springs
1. Standart nominal widths : 32, 40*, 45, 50*, 55, 60*, 65, 70, 80, 90*, 100 & 125mm.
2. Standart nominal thickness : 3,2; 4,5; 5; 6; 6,5; 7; 7,5; 8; 9; 10; 11; 12; 14; & 16mm
3. The recommended eye bore diametrs : 19, 20, 22, 23, 25, 27, 28, 30, 32, 35, 38, 50, & 55mm.
4. The diameter of centre bolts:
4. Pegas Daun / Leaf Spring (laminated or carriage spring )
5. Clip section and sizes of rivets & bolts
4. Pegas Daun / Leaf Spring (laminated or carriage spring )
Materials for leaf springs
1. Automobiles : 50Crl, 50Crl V23,55Si2 Mn90 (Hardened & Tempered)
2. Rail road C 55 (water – Hardened), C 75 (oil – Hardened), 40 Si2 Mn 90 (Water – Hardened), 55Si2 Mn90 (oil – Hardened)
3. All values are for oil quenched condition and for single heat only.
B. Bahan Pegas (Material) Depends on what they are used
1. Severe service2. Average service3. Light service
Severe service Rapid continous loading Ratio of minimum to maximum load is one half Automotive valve springs
Average service Intermittent operation loading Ratio of minimum to maximum load is one half Engine - Governor springs
Light service Very infrequently varied Load Safety valve springs
B. Bahan Pegas (Material)
B. Bahan Pegas (Material)
B. Bahan Pegas (Material)
B. Bahan Pegas (Material)
-The material treatment of helical springs both Cold Formed or Hot Formed.
-The material treatment depends on the size of the wire.
-Wires : < 10 mm Cold > 10 mm Hot
- The Srength size- Small size have greath strength & less ductility cold working
http://www.masterspring.com/spring-wire-form-products/custom-springs/torsion-springs/http://www.enginehistory.org/Propellers/Governors/hydgov.shtmlhttp://www.automotiveillustrations.com/tutorials/how-to-draw-a-car.htmlhttp://www.islandnet.com/~westisle/History/steam2.htmlhttp://www.tanhov.com/ProductShow/Pressure-Safety-Valve/Balance-Bellows-Safety-Valve-With-Jacket.htmlspringsandthings.comalibaba.com
Sumber
A semi-elliptical laminated vehicle spring to carry a load....kg is to consist of seven leaves .....cm wide, two of the leaves extending the full length of the spring. The spring is to be 110 cm in length and attached to the axle by two U-bolts .... Cm apart. These bolt hold the central portion of the spring so rigidly that they may be considered equivalent to a band having a width equal to the distance between bolts. The leaves are to be silico-manganese steel. Assuming an allowable stress of 3500 kg/cm2, determine :a. Thickness of the leavesb. Deflection of the springc. Diameter of the eyed. Length of the leaves e. Radius to which leaves should be initially bentAssume modulus of elasticity as 2,1x10^6 kg/cm2