Mechanical Engineering - Machine Design - Discussion

9. 

The application of third type levers is found in

[A]. handle of a hand pump
[B]. hand wheel of a punching press
[C]. lever of a loaded safety valve
[D]. a pair of tongs

Answer: Option D

Explanation:

No answer description available for this question.

Patel said: (Mar 17, 2013)  
What is mining of tongs?

Pavankumar said: (Jul 9, 2013)  
A lever is a simple machine that makes work easier for use; it involves moving a load around a pivot using a force. Many of our basic tools use levers, including scissors (2 class 1 levers), pliers (2 class 1 levers), hammer claws (a single class 2 lever), nut crackers (2 class 2 levers), and tongs (2 class 3 levers).

In a Type 1 Lever, the pivot (fulcrum) is between the effort and the load. In an off-center type one lever (like a pliers), the load is larger than the effort, but is moved through a smaller distance.

In a Type 2 Lever, the load is between the pivot (fulcrum) and the effort.

In a Type 3 Lever, the effort is between the pivot (fulcrum) and the load.

Rajesh Kumar said: (Jul 11, 2015)  
Pictures can make clear understanding.

Ameet said: (Sep 28, 2015)  
Pair of tongs comes under 1st class of levers.

Pinninti said: (Feb 18, 2016)  
A pair of tongs comes under the first type, because fulcrum is at middle, load and efforts are either end. Depending upon its design its mechanical advantage varies from <1 to >1.

Jeeve said: (Jun 10, 2016)  
If it is sugar tongs the answer given above is correct.

For welding tongs it would be Type 1.

Bhanu Teja said: (Oct 22, 2016)  
The 3rd class lever means pivot at the end, load at other end and effort is in the middle. For example, our human arm. Bicep is effort palm is where you take the load.

Shubham Gupta said: (Nov 27, 2016)  
There are two types of tongs one comes under type 1 and other one comes under type 3. If load is applied in between fulcrum and resistance then that type of tong is type 3 tong and if fulcrum is in between effort and resistance then it is of type 1 (scissors is the similer example of type 1 tong).

Akash said: (Jun 29, 2017)  
Answer is C (in safety valve effort is at mid of load and hinge).

Reddy said: (Jul 15, 2018)  
Answer 'C' is correct, agree @Akash.

Soustabh said: (Jul 19, 2021)  
Tong is not Third class lever.

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