GEAR TRAINS | TYPES | T.O.M. | MECHANICAL ENGINEERING

GEAR TRAINS

Introduction :-

                              " Geal train is the combination of gear wheel which is used to transmit motion and power from one shaft to another shaft"

"गियर ट्रेन में दो या अधिक gears का संयोजन होता है जिसके द्वारा एक सबसे दूसरे साथ में पावर ट्रांसमिशन की जाती है | "

Classification of gear trains :-

1. Simple gear train

2.  Compound gear train

3. Epicyclic gear train 

4  Reverted Gear train

1.Simple gear train :-

                                          When there is only one gear on each shaft .it is known as simple gear train. The gears are represented by their pitch circles.

 इस प्रकार की गियर ट्रेन में प्रत्येक सॉफ्ट पर एक ही गियर लगा होता है तथा प्रायः ड्राइवर एवं ड्रिवन gears के बीच एक या अधिक आइडलर गियर होते हैं |

Simple gear train

Let, 

N1 = Speed of gear 1(or driver) in r.p.m.,

N2 = Speed of gear 2 (or driven or follower) in r.p.m.,

T1 = Number of teeth on gear 1, and

T2 = Number of teeth on gear 2.

Since the speed ratio (or velocity ratio) of gear train is the ratio of the speed of the driver to

the speed of the driven or follower and ratio of speeds of any pair of gears in mesh is the inverse of Their number of teeth, therefore 

 

Speed ratio  :-    N1/N2  = T2 / T1

2. Compound gear trains :-

                          When there are more than one gear on a shaft,. it is called a compound

train of gear. 

 इस प्रकार की गियर ट्रेन में एक ही सॉफ्ट पर दो या दो से अधिक गियर दृढ़ता पूर्वक लगे होते हैं  इसलिए से कंपाउंड गियर ट्रेन कहते हैं| 

In a compound train of gears, the gear 1 is the driving gear mounted on Shaft A, gears 2 and 3 are compound gears which are mounted on shaft B. The gears 4 and 5 are also 

compound gears which are mounted on shaft C and the gear 6 is the driven gear mounted on shaft D.

Let 

N1 = Speed of driving gear 1,

T1 = Number of teeth on driving gear 1,

N2 ,N3 ..., N6 = Speed of respective gears in r.p.m., and

T2 ,T3...., T6 = Number of teeth on respective gears.

Speed ratio :- 

 N1/N2 × NE/N4 ×N5/N6 = T2/T1 ×T4/T3× T6/T5

OR   N1/N6  =  T2/T1 ×T4/T3× T6/T5

 3.Epicyclic gear trains:- 

                                                  the axes of the shafts, over which The gears are mounted, may move relative to a fixed axis. Are known as epicyclic gear train. 

इस प्रकार इस प्रकार की गेर ट्रेन में गियर प्रकार लगे होते हैं कि वे एक दूसरे के सापेक्ष घूम सकें | इस प्रकार की गेर ट्रेन का use high velocity ratio के लिए किया जाता है 

Here below the table of some conditions of motion of Epycyclic gear train. 

4.Reverted gear train:-

                  

  When the axes of the first gear (i.e. first driver) And the last gear (i.e. last driven or follower) are co-axial,  then the gear train is known as reverted gear train.