This article deals with common basic concepts to kept in mind for

New GATE examination Pattern : GATE 2014

**theory of machine/Dynamics of Machine**subject.New GATE examination Pattern : GATE 2014

- A kinematics chain needs a minimum of 4 link and 4 turning pairs.
- If the frequency of oscillation on earth is n then the frequency of oscillation on the moon will be n/√6.
- The biflar suspension method is used to find out moment of inertia.
- The total number of instantaneous centers for a mechanism of n link is equal to n(n-1)/2.
- In case of an elliptical trammel two pairs turn and two pairs slide.
- A shaft revolving in a bearing forms a lower pair.
- For kinematic chains formed by lower pair the relation between the number of link L and the number of joint J is given by L = 2/3 (J+2).
- The mechanism used to enlarge or reduce moments for reproducing drawings to different scales is called pantograph.
- The number of links in a pantograph is to 4.
- If a practical of a link has a velocity that changes both in magnitude and direction at any instant, then it must have two components of acceleration e.g., centripetal. And tangential.
- The Klein’s method of construction for reciprocating engine mechanism utilities a quadrilateral similar to the diagram of mechanism for reciprocating engine.
- In elliptical trammels have two pairs turning and two pairs sliding.
- When a ship travel in a sea, the effect of the pitching is more dangerous.
- If ф is angle of friction, the limiting value of tan ф will be µ.
- Multiple collars are provided on a flat collar pivot bearing to distribute the axial load due to limiting bearing pressure on a collar.
- Slip in belt drive is different between the linear speed of the rim of pulley and the belt on it.
- In case of flat belt drive the length of belt in case of gross belts depends on the sum of the diameters of pulleys.
- A pantograph is a mechanism having lower pairs.
- Kinematic pairs are those pairs that have two elements that allow relative motion.
- A cam with a roller follower would constitute higher pair.
- Peaucellier mechanism has eight links.
- Hart mechanism has six links.
- For a kinematic chain to be considered as mechanism one link should be fixed.
- The cam angle is the angle of rotation of the cam for a definite displacement of the follower.
- Klein’s construction is used to find out acceleration of various parts.
- For a stable governor there is one radius of the governor weight for each equilibrium speed.
- In case of a governor isochronous is only one equilibrium which is constant for all radii of rotation of the bells within the working range.
- Module can be expressed in mm.
- The bipolar suspension method I used to find out moment of inertia.
- Instantaneous centre of rotation of a link in a four bar mechanism lies on a point obtained by intersection of extending adjoining links.
- A reverted gear train is one in which the first and last gear are on the same shaft.
- In case of spur gears the flank of the tooth is the part of the tooth surface lying below the pitch surface.
- In case of cross helical worm the axes of two shafts are non parallel-non-interesting.
- In case of gears the addendum is given by one module.
- Gears for watches are generally manufactured by stamping.
- A cam where in the follower reciprocates or oscillates in plane parallel to the axis of the cam is called cylindrical cam.
- Rope break Dynamometers uses no lubricant.
- Tesla fluid friction dynameters used for power measurement when the speed is high and the viscous force is small.
- Hydraulic Dynamometers is widely used for absorption of wide range power at wide range of speed.
- The secondary disturbing force
because of inertia of reciprocating mass is given by W/g ω
^{2}r/n cos θ. - In a balancing machine the units for unbalance measurements are gm-cm.
- In a hartnell governor if the stiffness of spring is increased the governor will become less sensitive.
- The supply of working fluid to the engine to suit the load conditions can be controlled by governor.
- The governor used in gramophone is of pickening type.
- A porter governor could be classified as dead weight type governor.
- The function of a governor is to adjust variation of speed by varying the input to the engine.
- If D and T be the pitch circle diameter and no. of teeth of a gear, then its circular pitch p = π D/T.
- If D
_{1}and T_{1 }be the diameter and no. of teeth of gear 1 and D_{2}and T_{2}the corresponding value of other gear in mesh, then ratio N_{1}/N_{2}, will be equal to D_{2}/D_{1}. - A scott-russel mechanism is made up of sliding and turning pairs.
- Ackerman steering gear is made up of turning pairs.
- A sliding crank chain is made up of three turning and one sliding pairs.
- A motor car takes a bend of certain radius in right hand direction when moving at some speed. If engine rotates in a clockwise direct when viewed from front, then because of centrifugal force reaction on outside wheel is increased and on inside wheels decreased.
- If δ be the static deflection of shaft under the gravity load, then natural frequency of the system in case of the longitudinal and transverse vibration is equal to 1/2 π √g/δ.
- Cold working increased the fatigue strength.
- Coaxing is the procedure of increasing fatigue limit by overstressing the metal by successively increasing loadings.
- The notch angle of the Izod impact
test specimen is 45
^{0}. - In vicker’s hardness testing, the
pyramid indentor apex is 40
^{0}.

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