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# Essay: Hydraulic jacks

• Subject area(s): Engineering essays
• Published: 8 October 2015*
• File format: Text
• Words: 1,071 (approx)
• Number of pages: 5 (approx)

## Text preview of this essay:

Hydraulic jacks are widely used in the automotive industry to lift and support vehicles to facilitate repairs .Hydraulic jacks are also found in a variety of specialized application including lifting racing cars ,semi-trucks ,airplanes and forklifts .This jack are widely used across the globe and have outweighed the use or application of screw jacks in a variety of engineering industries .Hydraulic jacks are typically used for shop work ,rather than an emergency jacks to be carried with vehicle in case of a flat tire. They use a fluid, which is incompressible .Oil is used since its self-lubricating
In history the first hydraulic jack was patented by Richard Dudgeon in 1851. Prior to its invention the hydraulic jacks job was performed by screw jacks .Screw jacks require a lot of time and effort to be used by the operator to raise and lower a load compared to hydraulic jacks
Hydraulic jacks use Pascal principal in order to perform the required job. The principal is named after Blas?? Pascal who lived in the 17 century that is between 1623-1662 .The paschal principal or Pascal law states ‘in a fluid at rest in a closed container, a pressure change in one part is transmitted without loss to every portion of the fluid and to the walls of the container .Pressure is equal to the force divided by the area on which it acts .According to Pascal principle, in a hydraulic system, a hydraulic system being a system containing a fluid in high pressure and In motion ,a pressure exerted by a piston produces an equal increase in pressure on another piston in the system. If the second piston has an area ten times that of the first, then the force on it is ten times greater, though the pressure is the same as that of the first piston .This effect is exemplified by the hydraulic jack or the hydraulic press
Types of hydraulic jacks
2.2.2.1 Bottle jack
A bottle jack or whiskey jack is a hydraulic jack which resembles a bottle in shape .It has a cylindrical body and neck from which the hydraulic ram emerges .In a bottle jack the piston is vertical and directly supports a bearing pad that makes contact with the object being lifted .With a single action piston the lift is less than twice the collapse height of the jack making it suitable for vehicles with a relatively high clearance
Bottle jacks are expensive and advanced than scissor jacks; they use an advanced hydraulic system to lift up several tons. These jacks have a cylinder with a plunger and pup filled with hydraulic oil. When the plunger is lifted up and down with a small handle pressure build up inside the cylinder ,lifting the top post and the car resting on it .They are rated by the amount of weight they can support without collapsing and have the benefit of taking very little physical effort to adjust .They are also versatile since they can be placed in tight spots and provide good leverage .They have in recent years been used in search and rescue mission ,as result they are now standard equipment in fire stations and rescue teams
Bottle jacks are also used for spreading, bending, pushing or straightening requirements. Newer versions have undergone some slight design changes, including chromed pump, piston and ram to provide for added resistance to rust. The base and cylinder of bottles jacks are electrically welded for strength, and all models are capable in working upright, angled or horizontal positions
Standard bottle jacks have an attached pressure gauge that allows the read the amount of pressure they use .They come in 12, 20,30 and 50 ton models .The 30,50 ton versions have a port tapped into the in order to make them interchangeable .In this way ,the user can select the tonnage needed and adjust accordingly .Other versions are geared only towards the tonnage they are made of .Bottle jacks have a common release valve assembly .The stem release valve is created for easy access and release in case of an emergency to avoid serious accidents.
Fig 1.8 hydraulic bottle jack
1. The jacks simple design minimized cost ,size and weight so it ca be stored easily
2. Does not relay of electricity
1. Operating the jack can be difficult
2. Requires the operator to be near ,practically underneath the car to operate
3. The product does not offer stability from the sides
2.2.2.2 Floor jacks
Floor jacks also known as trolley jacks are hydraulic jacks designed for greater lift and improved stability .They range in weight from 2 ton to 4 ton and have additional control option such as breaking control and jack locks .They are safe to use on gravel and dirt because they have a wider base and are less likely to collapse or shift out of place. They are the only jacks that are safe to leave under the car without jack stands while the car is being serviced
Fig 1.9 floor jack
1. They have wheels which allow the operator to move it anywhere within the garage .The average off height for floor jack is six inches to a foot of the ground
2. They also come with safety features that will help keep the operator safe when working on a vehicle .The most safety feature is an overload system which does not allow the jack to lift if the capacity is over the limit for it
1. They are complex compared to other jacks
2. They are expensive since they require more power to compress
3. Leaks can pose a safety hazard because they can Cause a fire or corrosion
4. Air treatment before makes it expensive
2.2.3 Pneumatic jacks
A pneumatic jack is a type of hydraulic jack that is actuated by compressed air instead of oil. This eliminates the need of for the user to actuate the hydraulic mechanism .Saving effort and potentially increasing speed, such jacks are also able to be operated by normal hydraulic actuation method thereby retaining functionality even if a source is compressed air is not available
Fig 7 pneumatic jack
1. Require simple maintenance care
2. A loaded light vehicle can be easily be lifted
3. Checking and cleaning is easy since the main parts are screwed up
4. Handling is easy
5. Manual power not required
6. Repairing is easy and
7. Replacement of parts is also easy
1. Expensive when used continuous
2. Variation in the load it can handle
3. Noisy thus require a silencer