What Is Crank And Slotted Lever Mechanism?

Crank and Slotted Lever Mechanism is a type of single slider crank chain mechanism inversion and four-bar mechanism. Crank and Slotted Lever Mechanism is one of the two types of Quick Return Mechanism (whereas; the Whitworth mechanism is another type of quick return mechanism). Crank and Slotted Lever Mechanism is also called Crank and Slotted Quick Return Mechanism. 

Every machine and machine tool works with a principle to perform the a specified action. Few actions are reciprocating and few are rotary type, which sourced by Electrical Motor. As we know that the quick return mechanism is a type of mechanism, where the return stroke of the ram is quicker than the forward stroke. So, this type of mechanisms (Crank And Slotted Lever, Whitworth Quick Return Mechanisms) will be used to convert the rotary motion of the Motors into required action and operation.

Parts of Crank And Slotted Lever Mechanism:

The parts of the crank and slotted lever mechanism are limited. Its construction is simple and plays an important role too. The crank and slotted lever mechanism do consists of four links and pairs because it is a single slider crank chain. Three of the four pairs are turning pairs, and the remaining one is a sliding pair. A typical crank and slotted mechanism do consists of the following parts.

• Ram or Lever: It is the sliding pair that moves in to and fro motion.
• Crank: The Crank is the rotary part (turning pair) that will help the whole construction to convert the rotary motion of gear into the sliding motion of the ram.
• Gear: The gear is the rotary part (one of the turning pair) that is connected to the motor. (the source)
• Slotted Bar: The slotted bar is one of the three turning pairs, where it is connected to the gear. It is the connector between gear and crank that helps to convert the rotary motion of the gear into sliding motion with the help of its to and fro motion.

Also Read

• Whitworth Quick Return Mechanism – Whitworth Mechanism Working, and Advantages
• Basic Concepts of Theory Of Machines

Working Of The Crank And Slotted Lever Mechanism:

The working of the crank and slotted lever mechanism looks the same as the Whitworth mechanism. The crank and slotted mechanism do work with the help of a motor. The gear is connected to the Motor; as the motor rotates, the gear will rotate. The slotted bar is connected to the gear with the help of a slot. The slotted bar will move in to and fro motion due to the rotation of the gear. The slotted bar movement will make an angle of alpha as shown below.

As the slotted bar turns, the crank will rotate and helps the ram to achieve the sliding movement.

Advantages of Crank And Slotted Lever Mechanism:

The advantages of crank and slotted lever mechanism are as follows

• Crank and Slotted Mechanism is used to converting the rotary motion of the motor to the reciprocating motion.
• The construction is very simple and even the operating process is easy.
• No need for high maintenance costs.
• The working of the crank and slotted mechanism is also simple.

Application Of Crank And Slotted Lever Mechanism:

• The main application of the crank and slotted lever mechanism can be seen in Shaper Machine. To understand the crank and slotted mechanism let us elaborate the Shaper internal mechanism. (Read about the Shaper).

The shaper consists a tool that fixed to a Ram (which is a slider link); we can say that the ram is the part that will machine the workpiece. But the internal mechanism that allows the ram to move is the Crank and Slotted Lever Quick Return Mechanism. A gear is connected to the motor; the connecting rod and crank will turn in a way to achieve the sliding motion of the ram.

In the quick return mechanism (whether crank and slotted or Whitworth), the backward movement of the ram is faster than the forward movement of the ram. Forward Movement is slower because the slow machining will give good finishing. The machining time of the crank and slotted lever mechanism can be taken as the ratio of time of cutting stroke (or forward stroke) to the time of return stroke (or backward stroke).

• Crank and Slotted Lever Mechanism is used in Slotting machines for performing the slots on the workpiece.
• In addition to these, the application of crank and slotted lever mechanism in rotary type internal combustion engines also plays an important role.

Conclusion:

If we observe the shaper machine internal mechanism closely, the shaper internal mechanism is the combination of the crank and slotted lever mechanism and the Whitworth mechanism because both mechanisms are the types of quick return mechanisms. As the name crank and slotted lever mechanism indicate, the applications do consist of a crank and slotted lever as its parts. The crank is a rotary type and the slotted lever is a to and fro type but both can be counted as the turning pair.