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SSC JE Mechanical study materials
SSC JE Mechanical study resources

SSC JE Mechanical: Part-B: General Engineering (Mechanical)

SSC JE Mechanical · Work through your exam, one topic at a time.

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Part-B: General Engineering (Mechanical)

Part-B General Engineering (Mechanical)

Part-B (Paper-II) goes deeper into mechanical engineering applications: design of machine elements, heat transfer, refrigeration and air conditioning, CAD/CAM, metrology, industrial engineering, and advanced manufacturing. Questions are still objective but require multi-step reasoning and familiarity with standards.

Core rules and concepts

  • Design: use ASME/ISI codes for keys, couplings, bearings; check for bearing stress, shear stress, and factor of safety. For a shaft, combine bending and torsion: τ_max = (16/πd³)√(M² + T²).
  • Heat transfer: Fourier's law Q = −kA dT/dx; Newton's law Q = hA(T_s − T_∞); Stefan–Boltzmann Q = εσA(T⁴ − T_∞⁴); LMTD for heat exchangers.
  • Refrigeration: COP = refrigeration effect / work input; for Carnot refrigerator COP = T_L/(T_H − T_L); know vapor-compression cycle components.
  • Metrology: least count of vernier = 1 MSD − 1 VSD; micrometer least count = pitch/divisions; tolerance stack-up.
  • Industrial engineering: work study, time study, EOQ = √(2DS/H), PERT/CPM critical path.
  • CAD/CAM: G-codes, M-codes, CNC interpolation, and rapid prototyping.

Worked example

A Carnot refrigerator operates between −5°C and 27°C. Find its COP. Reasoning: Convert to kelvin: T_L = 268 K, T_H = 300 K. COP = T_L/(T_H − T_L) = 268/(300 − 268) = 268/32 = 8.375.

Traps that cost marks

  • Using Celsius instead of kelvin in Carnot COP.
  • Forgetting to add atmospheric pressure when using gauge pressure in heat transfer.
  • Mixing up LMTD with arithmetic mean temperature difference for large ΔT.
  • In metrology, reading the main scale and vernier scale in the wrong order.