Governors MCQ Quiz in मराठी - Objective Question with Answer for Governors - मोफत PDF डाउनलोड करा

Explanation:

Isochronous Governor: 

• A governor is said to be isochronous when the equilibrium speed is constant (i.e. range of speed is zero) for all radii of rotation of the balls within the working range, neglecting friction. 
• The isochronism is the stage of infinite sensitivity.
• A spring-loaded governor can only possibly be an Isochronous governor.

Hunting: 

• If a governor is too sensitive, a small variation of speed causes large change in the sleeve movement. Thus, a governor is said to be hunt if the speed of the engine fluctuates continuously above and below the mean speed.

Stability: 

• A governor is said to be stable when for each speed within the working range there is only one radius of rotation of the fly-ball at which the governor is in equilibrium.

Concept:

For the governor to be stable, the controlling force (FC) must increase as the radius of rotation (r) increases.

The relation between the controlling force (FC) and the radius of rotation (r) for the stability of spring controlled governors is given by the following equation

FC = a.r – b

Concept:

Coefficient of detention is given by:

\(\frac{{Friction\;force\;at\;sleeve}}{{Weight\;of\;ball}}= \frac{f}{{Mg}} \)

Calculation:

Given:

Weight of the ball = 50 N, Friction force (f) = 10 N.

Coefficient of detention \(=\frac{{Friction\;force\;at\;sleeve}}{{Weight\;of\;ball}}= \frac{f}{{Mg}} \)

Coefficient of detention \(= \frac{{10}}{{50}}\)

Coefficient of detention = 0.2

Explanation:

Controlling force:

Controlling force is equal and opposite to the centrifugal force and acts readily inward. It is supplied by:

• The gravity of the mass of ball in case of watt governor.
• The gravity of the mass of ball and deadweight of the sleeve in case of porter and proell governor.
• The gravity of ball masses and spring force in Hartnell and Hartung governors.
• Controlling force curve for spring-loaded governor.

In the diagram, line III and IV both come under a stable governor but line IV is more stable than line III, so option IV is the correct answer.

Concept:

Power of Governor: The power of a governor is the work done at the sleeve to change its equilibrium condition for a given percentage change of speed. It is the product of the mean value of the effort and the distance through which the sleeve moves.

Power = Mean effort × lift of sleeve

\(P=\frac{E}{2}\times Lift~of~sleeve\)

Concept:

For watt governor

\(h = \frac{{895}}{{{N^2}}}\;metres\)

Calculation:

\({h_2} - {h_1} = 895\left( {\frac{1}{{N_2^2}} - \frac{1}{{N_1^2}}} \right) = 895\left( {\frac{1}{{{{25}^2}}} - \frac{1}{{{{50}^2}}}} \right)\)

h2 – h1 = 1.074 mm

Concept:

The function of a governor is to maintain the speed of an engine within prescribed limits for the various altering load conditions.

Governors are classified as:

• Centrifugal Governor
• Inertia Governor

Centrifugal Governors are classified as:

• Dead Weight Governors:
  • Porter governor
  • Proell governor
• Spring controlled governors:
  • Hartnell governor
  • Hartung governor
  • Pickering governor

Terms used in Governor

• Height of Governor: Vertical distance from the center of the ball to a point where arms intersect on the spindle axis.
• Sleeve lift: Vertical distance with the sleeve travels because of a change in equilibrium speed.
• Equilibrium speed: The speed at which the governor balls, arms are in complete equilibrium and the sleeve does not tens to move upwards or downwards.
• Sensitiveness: The sensitiveness is defined as the ratio of the difference between the maximum and minimum equilibrium speeds to the mean equilibrium speed. 
• \({\rm{Sensitiveness = }}\frac{{{\rm{Range}}\,{\rm{of}}\,{\rm{Speed}}}}{{{\rm{Mean}}\,{\rm{Speed}}}} = \frac{{{\omega _{\max }} - {\omega _{\min }}}}{{{\omega _{{\mathop{\rm m}\nolimits} ean}}}}\)
• Hunting Governor: When the speed of the governor continuously fluctuates above or below the mean speed this type of governor is known as hunting governor.
• Stable Governor: When there is only one radius of rotation of governor ball for all speed within the working range this type of governor is known as stable governor.
• Isochronous Governor: If a governor is having the same radius of rotation for all the rotational speed then it is known as isochronous governor.

Concept:

Governors are classified as:

• Centrifugal Governor
• Inertia Governor

Centrifugal Governors are classified as:

• Dead Weight Governors:
  • Porter governor
  • Proell governor
• Spring controlled governors:
  • Hartnell governor
  • Hartung governor
  • Pickering governor

Explanation:

Governor: It is a device used for maintaining a constant mean speed of rotation of the crankshaft over long periods during which the load of the engine may vary. Governor maintains constant speed by controlling the supply of working fluid as the load varies.

Governors are classified as:

• Centrifugal Governor
• Inertia Governor

Centrifugal Governors are classified as:

• Dead Weight Governors:
  • Porter governor
  • Proell governor
• Spring controlled governors:
  • Hartnell governor
  • Hartung governor
  • Pickering governor

Hence except proell governor all other options are spring controlled governor.

Concept:

For watt governor

\(h = \frac{{895}}{{{N^2}}}\;metres\)

Calculation:

\({h_1} - {h_2} = 895\left( {\frac{1}{{N_1^2}} - \frac{1}{{N_2^2}}} \right) = 895\left( {\frac{1}{{{{50}^2}}} - \frac{1}{{{{51}^2}}}} \right)\)

h1 – h2 = 13.90 mm