Gear Train is an important topic from GATE viewpoint and every year there is at least 1 question asked from this topic. To cover this topic, Gate - PrepLadder has shared this blog to help the candidates with this topic.

This article will cast light on the important sub topics to prepare under Gear Trains/What to prepare from Gear Train for Gate 2017 in order to answer most of the questions asked from Gear trains.


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The combination of meshing of two or more gears in order to transfer power from one shaft to another is called Gear Train.

Important Topics From Gear Train / What to prepare for GATE 2017 

Now the things /important topics  that you should prepare from Gear trains for GATE 2017 are mentioned as follows.

  • You should prepare the types of gear trains viz. Simple gear train, compound gear train, Reverted Gear train and epicyclic gear train.
  • Prepare the numericals based on the above mentioned types of gear trains. Numericals are generally based on the Speed Ratio, Train Value, Number of teeths, etc.
  • Next is the design of spur gear which is very important topic. Same as the previous point prepare numericals based on this topic.

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  • Reverted gear train should also be prepared whole heartedly.
  • Epicylic gear train is another major topic and numericals based on this are mandatory if you wish to score well in the exam. Velocity ratio based numericals are important.
  • The next one is related to the Epicyclic gear train viz. Compound Epicyclic gear train. Numericals are imortant.
  • Torques acting in epicylic gear train and epicyclic train with bevel gears are further subtopics of Epicyclic gear train.

If these topics are prepared for GATE 2017 in the gear trains, then it is more than sufficient to answer all the related questions.

Following are the solved questions based on the Gear trains asked in the previous GATE exam papers to give you an idea about the types of questions asked.

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Solved Questions From GATE FROM GEAR TRAIN

Question 1.


As shown in the figure of an epicyclic gear train, The sun gear (2) on the input shaft is a 20 teeth external gear. The planet gear 3 is a 40 teeth external gear. The ring gear 5 is a 100 teeth internal gear. If the ring gear 5 is fixed and the gear 2 is rotating at 60 rpm ccw. 

Then what will be the rotating speed of arm attached to the output shaft?

(A) 10 rpm ccw

(B) 10 rpm cw

(C) 12 rpm cw

(D) 12 rpm ccw


Answer  A


Solving (1) and (2), we get


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Question 2

A compound gear train has four gears namely P, Q, R and S having the number of teeth 20, 40, 15 and 20 respectively. Gear Q and R are mounted on the same shaft. The diameter of the gear Q is twice that of gear R. if the module of the gear R is 2 mm, then what is the centre distance in mm between gears P and S. Refer to the fig. Given below



(A) 40

(B) 80

(C) 120

(D) 160

Answer B



Explanation :

Module of meshing gear pair are equal.



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