Introduction
Mechanical monkey
A jack is a mechanical device used to lift heavy loads or apply great forces. Jacks employ a screw thread or hydraulic cylinder to apply very high linear forces.
A mechanical jack is a device that lifts heavy equipment. The most common form is a car jack, floor jack or garage jack that raises vehicles so that maintenance can be performed. Car jacks often use mechanical advantage to allow a human to lift a vehicle with manual force alone. More powerful jacks use hydraulic power to provide more lift over greater distances. Mechanical jacks are generally rated for maximum lifting capacity.
scissor jack
Scissor jacks are simple mechanisms used to drive large loads over short distances. The power screw design of a common scissor jack reduces the amount of force required by the user to actuate the mechanism. by a power screw. A scissor jack is operated by simply turning a small crank inserted into one end of the scissor jack. This crank is usually “Z” shaped. The end fits into a ring hole mounted on the end of the screw, which is the object of force in the scissor jack. When this crank is turned, the screw turns and this raises the jack. The screw acts as a gear mechanism. It has teeth (screw thread), which rotate and move the two arms, producing work. Just by turning the screw thread, the scissor jack can lift a vehicle that weighs several thousand pounds. The power screw on a scissor jack is the basis of the entire scissor jack mechanism.
scissor jackProblem statement:
The most common problem encountered when using a scissor jack is the instability of the jack when jerking to loosen the wheel nut. Furthermore, the common jack with a small base cannot provide adequate support on uneven surfaces, especially off-road, and no tilt on that jack is tolerable.
Goal:
The project is related to the design of a simple scissor jack and its analysis, along with structural improvements to create a modified jack that is very stable and can withstand sufficient load on uneven surfaces, with some tilting also permitted.
The project also aims to design and find stresses, efficiency and expected life of the screw. We strive to develop a screw jack that is economical, has a long life and can be handled roughly.
Road map:
Here, we outline the timeline for completing various aspects of the project. The schedule is set so that the project is completed in phases. Phase I is market research, Phase II consists of the design process, Phase III involves PRO-e design modeling and simulation in ANSYS software, and the final aspect of the project is the presentation and work that has been done for that.
Scissor jack:
Specifications
The term “scissor jack” describes a wide variety of tools that follow the same principle: using crossbeams to lift something. They do this by acting on the object they are lifting diagonally; the elevator on the right side lifts the object on its left side and vice versa. This allows the user to store the jack when not in use (with the diagonal beams flat) and expand it when needed.
Set
A scissor jack has four main metal parts and two base ends. The four metal pieces are all connected at the corners with a screw that allows the corners to rotate. A screw thread runs through this assembly and the corners. As the screw thread is turned, the jack arms travel through it and collapse or come together, forming a straight line when closed. Then, going back to the other side, they climb up and join together. When opened, the four metal arms contract, coming together in the middle, lifting the jack. When closed, the arms move away again and the jack closes or flattens again.
Working
A scissor jack uses simple gear theory to obtain its power. As the screw section is turned, the two ends of the jack move closer together. As the screw gears push the arms upward, the amount of force applied is multiplied. It takes a small amount of force to turn the crank, but this action causes the belt arms to slide together.
As this happens, the arms extend upward. The gravitational weight of the car is not enough to prevent the jack from opening or the screw from turning, as it does not apply force directly to it. If you pressed directly on the crank, or supported your weight against the crank, the person would not be able to turn it, even if your weight is a small percentage of the cars.
Components
• Frame
• Power screw
• Rivets
• Coupling nut
• Hand crank
Download
DESIGN AND ANALYSIS OF SCISSOR JACK FULL REPORT.pdf
File size: 800 KB
