(SEM V) THEORY EXAMINATION 2017-18 KINEMATICS OF MACHINES

Kinematics of Machines (NME-502)

Section-Wise Important Questions & Study Notes

SECTION–A

(Attempt all questions | 2 × 10 = 20)
This section checks definitions, short explanations, and basic concepts.
Write 2–3 lines, no long theory.

Lower Pair & Higher Pair
Lower pair has surface contact (slider-crank), higher pair has line/point contact (cam, gears).

Mobility / Degree of Freedom
Number of independent inputs required to define the motion of a mechanism.

Space Centrode & Body Centrode
Locus of instantaneous centres in fixed frame is space centrode; in moving frame is body centrode.

Coriolis Component of Acceleration
Additional acceleration when a point slides on a rotating link, acting perpendicular to relative velocity.

Slip & Creep in Belt Drive
Slip is relative motion between belt and pulley; creep is due to elastic stretch and recovery.

Straight Line Mechanism (Hart Mechanism)
Mechanism that generates exact straight-line motion without guideways.

Uniform Wear & Uniform Pressure
Conditions used in clutch and brake design to distribute frictional effects.

Brakes vs Dynamometers
Brakes absorb power; dynamometers both absorb and measure power.

Cam Terminology
Base circle, pitch circle, pressure angle, stroke—define briefly with sketch idea.

Law of Gearing
For constant velocity ratio, the common normal at the point of contact must pass through pitch point.

SECTION–B

(Attempt any THREE | 10 × 3 = 30)

Velocity, acceleration, brakes, gears – mix of theory & numericals.

1. Crank and Slotted Lever Quick Return Mechanism

Given dimensions → find cutting stroke, return stroke, time ratio, link length.
Always draw configuration diagram first.

2. Velocity & Acceleration Analysis (Fig. 2 / Fig. 3 Type)

Find:                                                                      Velocity of ram

Acceleration of ram                                              Acceleration of sliding block
Use velocity polygon & acceleration polygon.

3. Pivot Bearing Friction Loss

Calculate power loss using given load, speed, coefficient of friction, and geometry.

4. Band Brake (Uniform Pressure / Wear)

Find braking torque or effort using lever equilibrium and friction relations.

5. Instantaneous Centres (Four-Bar Mechanism)

Locate all ICs using Kennedy’s theorem and find angular velocities.

SECTION–C

(Attempt any ONE | 10 × 1 = 10)

3(a) Toggle Press Mechanism

Find velocity/force at slider and pressure at ram.  Explain mechanical advantage near toggle position.

OR

3(b) Aronhold–Kennedy Theorem             State and prove the theorem; explain significance with examples.