Quick Return Mechanism 3 Types, Working, Pros, Cons [PDF]

In this article, we shall be studying the definition, types, working principles, applications, advantages, and disadvantages of the Quick Return Mechanism. We have also provided a PDF for the same.

What is the Quick Return Mechanism?

A quick return mechanism is used in the shaper and slotter machine in which the circular motion is converted into a reciprocating motion so that the slider moves forward and backward. In the forward direction, the cutting process occurs while in return there is no such cutting.

Quick Return Mechanism Types

There are three types of quick return mechanisms which are as follows

  • Whitworth Quick Return mechanism
  • Crank and Slotted Link Mechanism
  • Hydraulic Drive

Whitworth Quick Return Mechanism

Here the rotary motion is converted into the oscillatory motion. In this mechanism, the bull gear is used and it has a crank pinion. The sliding block slides over the Crankpin and slides inside the slot of a crank plate and the connecting rod connects the pin at one end and ram at the other end.

The electric motor shaft drives the pinion and rotates the gear. Now the bull gear is also rotating along with the crankpin and the sliding block slides on the slot provided on the crank plate. So this process makes the ram move up and down by the connecting rod.

Whitworth Quick Return mechanism
Whitworth Quick Return Mechanism Diagram, Learn Mechanical

This mechanism was invented by Whitworth in the 1800s. The mechanism consists of a slider, crank, fixed link, slotted lever, connecting rod, and ram. The crank is connected to the slider and fixed link. When the cranks start rotating the connecting rod pushes forward and backward the ram.

Here the motion is converted into linear motion from rotary motion. To understand it clearly please see the diagram. The crank and slotted link mechanism are widely used in shaping machines like slotter machines, and shaper Machines for producing flat surfaces on the workpiece. The return stroke is much faster than the forward stroke in this mechanism.

Crank and Slotted Link Mechanism
Crank and Slotted Link Mechanism Diagram, Learn Mechanical

Hydraulic Drive

In the hydraulic drive, there is a piston inside the hydraulic cylinder that reciprocates. The piston rod is connected between the ram and the piston. Therefore ram reciprocates with the piston.

In the diagram, you can see there are two entries at the end of the cylinder. And below a control valve is attached which has four passes. Two entries from the cylinder to the control valve and the remaining two are connected through a reservoir.

hydraulic drive mechanism
Hydraulic Drive Mechanism Diagram, Learn Mechanical

Quick Return Mechanism Working Principle

Quick Return Mechanism Working Principle
Quick Return Mechanism Working Principle, Learn Mechanical

As you can see in the diagram there are four links and those are Slider, Crank, Frame, and Slotted Lever. Also it is connected through pairs which are as follows

  • Frame and Slotted lever: Turning Pair
  • Now Frame and Crank: Turning Pair
  • Crank and Slider: Turning Pair
  • Now Slider and Slotted lever: Sliding Pair

There are three turning Pairs and one sliding pair. It is also known as the Inversion of the Single slider crank chain mechanism. The connecting rod is fixed here.

  • The slider is free and it can slide in the slotted lever the upper end of the slotted lever is attached to the ram of the shaper machine through a linkage.
  • The crank and the slotted lever is fitted to the frame at point A and B respectively.
  •  Through a slider, the crank and slotted lever are connected.

Now when the power is supplied, the crank starts rotating and the motion is transmitted to the slider which is fitted inside the slotted lever therefore it starts oscillating. Now ram moves forward and it makes an angle of beta which is noted and In return, it makes an angle of alpha which is also noted. From the diagram, you can see that the beta angle is more than the alpha. So we can say that cutting strokes takes more time than returning strokes.

Advantages of Quick Return Mechanism

  • The process is automated.
  • The construction of the mechanism is not complicated.
  • It can perform operations like cutting, flattening, and slotting the workpiece.
  • The idle time is reduced because of the fast returning stroke.

Disadvantages of Quick Return Mechanism

  • In the returning stroke, there is no contact with the work so no cutting takes place hence the process takes much time to complete.
  • The forward stroke takes much time compared to the return stroke.
  • It takes more power to perform operations.
  • There is friction between the slider and the Piston.
  • Continuous it won’t work because of heat generated inside the piston and wear and tear can happen.
  • Balancing of linkage is also a major problem as this device is also linked to linkages.

Applications of Quick Return Mechanism

  • It is used in the shaper Machine for flattening the workpiece.
  • The same is used in the Slotter and Planer Machine.
  • It is also used in the Screw press, Mechanical actuator, and Rotary combustion Internal Engine.

Quick return mechanism animation

Video By EngineOn

Conclusion

In conclusion, the Quick Return Mechanism is a type of mechanical linkage that transforms rotary motion into reciprocating motion. It is widely used in various industrial applications such as shaping machines, stamping machines, and cutting machines. The Quick Return Mechanism has several advantages such as high efficiency, precise control, and low maintenance cost.

However, it also has some limitations such as the need for frequent lubrication, complex design, and limited stroke length. Overall, the Quick Return Mechanism is crucial in the manufacturing industry that plays a significant role in the automation and efficiency of various processes.

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