In the previous article, we have discussed what is the kinematic chain and the important types of kinematic chains. The Single Slider crank mechanism is one of the important kinematic chains. Let’s discuss the different inversions of the Single Slider crank.
Single Slider Crank Chain Mechanism
The Single Slider Crank Chain mechanism is nothing but the modified Four Bar mechanism. Unlike all the four turning pairs in the four-bar mechanism, The Single slider crank chain will consist of the three turning pairs and one sliding pair.
As you can see the 1.crank, 2.connecting link 3. fixed base as the fixed link 4. position moving in the crosshead are the four links. and the piston and the crosshead are making the sliding pair and the rest are making the turning pairs.
All the reciprocating Engines will be running on this mechanism only. This mechanism will convert the reciprocating motion into the rotary motion as well as the vice versa.
What is meant by the Inversion of a mechanism?
When we fix a Kinematic link in the Kinematic chain will make a mechanism, The Inversion of the mechanism is nothing but obtaining more mechanisms by fixing different Kinematic links in the kinematic chain.
Inversions of Single Slider Crank Chain Mechanism
There are different possibilities to make inversion for a Single Slider Crank Chain Mechanism. But for now, we will be discussing the most important inversions of Single Slider Crank Chain. Following are the different Inversion.
- Bull Engine (Pendulum pump)
- Oscillating cylinder engine
- Rotary internal combustion engine
- Crank and slotted lever quick return mechanism
- Whitworth Quick return mechanism
Bull Engine (Pendulum pump)
In this mechanism, the inversion can be obtained by fixing the sliding pair.
As you can see the schematic representation of the bull engine or the pendulum pump above. When the crank rotates then the connecting rod oscillates about the pivot point A. The piston attached to the piston rod will reciprocate.
Oscillating cylinder engine
Another Inversion of the single slider crank chain mechanism can be obtained by fixing the turning pair.
As you can see the schematic representation of the oscillating cylinder which is one of the inversions for the single sliding crank mechanism. In this oscillating cylinder engine, the connecting rod which makes the turning pair is fixed, instead of this connecting rod oscillation, the cylinder will oscillate when the crank rotates and is connected by the piston rod.
Rotary internal combustion engine
A rotary engine consists of the 7 cylinders in one plane and all revolve about the fixed centre as you can see in the below schematic representation.
These steam engines were used in the aviation engines back then. Nowadays most aviation engines are gas turbines. As you can see this type of inversion of the Single Slider Crank also one turning pair is fixed, but the turning pair is associated with the crank. But in the above oscillating engine, we have fixed the connecting rod instead. That is the difference between the oscillating cylinder engine and the rotary internal combustion engine.
This mechanism transmits the Reciprocating motion into rotary motion.
Crank and slotted lever quick return mechanism
In this type of Inversion of Single Slider Crank Mechanism also one turning pair is fixed as shown in the below fig.
This mechanism is used mostly in shaping machines and slotting machines and rotary internal combustion engines. As you can see from the above schematic representation of the crank and slotted lever mechanism, there will be a slotted bar which is fixed at one and at A. And also connected to the crank by the slider at B. As you can see the other end(P) of the slotted bar is connected to the ram of the machine where the tool post holds the tool. As the crank rotates, the slotted bar starts to oscillate forward and backwards. The name quick returns represent that when the slotted bar moves backward direction, it will be quicker than the forward movement. As it should travel the angle α while backward movement instead of the forward movement β. In the quick return mechanisms always α < β.
This mechanism transmits the rotary motion to the linear motion.
Whitworth Quick return mechanism
It is also used in the shaping and slotting machines as a quick return mechanism. Following is the schematic representation of the Whitworth Quick return mechanism.
In this mechanism also there will be a slotted bar that is fixed at point D and connected to the crank by a slider and at the other end connected to the connecting rod connected to the ram of the tool post. Here also the backward movement is quicker than the forward movement.
This mechanism also transmits the rotary motion to the linear motion.
These are the Inversions of Single Slider Crank Chain Mechanism.
We have discussed what is a Single Slider Crank Chain Mechanism. We have also discussed what are the Inversions of the Single Slider Crank Chain Mechanism. If you have any further thoughts on this topic, let us know in the comment section below.