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How Hydraulic Jacks Work
Any kind of jack has only one use, which is to lift heavy loads. Almost anyone involved with automotive would have used a jack at least once. Jacks can be divided into two categories: hydraulic jacks and mechanical jacks.
The word ‘hydraulic’ means to have something to do with liquid moving under pressure in a confined space. Hydraulic jacks do exactly this. Instead of using machinery to lift a heavy object, they depend on the physics of pressure.
A hydraulic jack moves the oil within them between two cylinders contained within the jack. This is done through the use of a pump plunger, which draws back and opens a suction valve. This draws oil into the pump chamber.
When the plunger gets pushed down, the oil gets pushed into the cylinder chamber through an external discharge valve. When the suction valve closes, pressure starts to build up in the chamber, and this makes the piston in the chamber rise and push your heavy object up.
By repeating this process, the object you are trying to lift can be pushed up higher.
Hydraulic jacks can generally lift up heavy objects higher than mechanical jacks can.
Types of Hydraulic Jacks
There are two main kinds of hydraulic jacks.
Also called floor jacks, trolley jacks are the most common type of hydraulic jack. They are usually used in professional environments, but also very commonly found in homes since their design makes them quite helpful.
A trolley jack comes with wheels so you can roll the jack around at any spot under your car and uses a long pump handle to release it so that the vehicle can be lifted. It is most commonly used for automotive mechanics but also frequently used in other industries.
The trolley jack is excellent for high ground clearance vehicles, and for lighter construction projects.
Trolley jacks also come in different types.
Extra-low trolley jacks
Used for raising vehicles that are similar to the jack in that they are also low. That is, vehicles with low chassis or reduced clearance will need this kind of jack. It comes with a foot pedal that helps the user lift the saddle up towards the load so they can lift it.
High-lift trolley jacks
Used for most 4x4s but they are also good for any vehicles that need a higher clearance.
Like the name suggests, they work with a scissoring mechanism that winds a bar in or out to lift the load. Scissor jacks are cheaper so they can be easier to acquire and sometimes they also come with a vehicle.
Extra large trolley jack
It has a lifting capacity of about 3 tons, and has a steel forged saddle that can last a long time. It is comparable to the high lift jack, except that it is larger and has a greater load capacity.
Long body trolley jack
It’s even better than the extra-large jack due to its greater load capacity. It can lift up to 5 tons, and is a bit longer than the extra-large model. It has excellent strength and stability and keeps very heavy vehicles lifted above the ground while you do your work.
10 ton long body trolley jack
This is a further upgrade from the 5-ton model. As expected, it can lift up to 10 tons, and can lift your regular vehicle about 57 cm off the ground. However, it is not perfect for all types of vehicles.
These jacks are all designed for different types of cars, so picking the right trolley jack for your vehicle would involve understanding what you need your jack for and how much load you want to lift. Based on this, you would be able to find the right trolley jack for yourself.
Trolley jacks are not just used for the vehicles themselves, but also to lift and maneuver components of vehicles around, such as the fuel tank.
A bottle jack is another common type of jack used in automotive work. It looks like a bottle, as the name suggests, and being shaped like a bottle, stands taller than a trolley jack. This means that even the lifting range of a bottle jack is much higher than a floor or trolley jack – from around 8-15 inches. This makes them unsuitable for lifting cars with lower ground clearance.
Bottle jacks are best for vehicles that have already raised a reasonable amount, such as jeeps or SUVs.
Instead of a lift arm like you’d find in a trolley jack, a bottle jack has a lifting rod. The mechanism behind it is very simple: you pump the arm and the piston will rise.
Bottle jacks can lift much heavier loads than most trolley jacks – up to 50 tons. They are often used for raising houses in groups in construction. When used on vehicles, bottle jacks will often have a block of timber to cushion the impact of the jack on the car’s body.
While bottle jacks aren’t great for lifting lower vehicles, their height range is not as great as a garage jack. One advantage is that bottle jacks, due to their vertical structure, take up a lot less space, and can also take more weight safely.
Are Trolley Jacks Better Or Bottle Jacks?
The kind of hydraulic jack you need depends on multiple things.
The most obvious one is the load capacity, since this is the main purpose. Trolley jacks can easily lift heavy weights, but their load capacity is much lower than that of bottle jacks. However, if the load you need to lift is lower and can be done with a trolley jack, you can consider the other factors.
One of these is the comfort level. Since bottle jacks have a higher height range than a trolley jack, they are not suitable for vehicles with low ground clearance, while trolley jacks can fit under them easily.
Another major point to consider is the base compression. Because trolley jacks have a longer base, they can distribute the weight of the object they are lifting across the base. This makes them much more stable than bottle jacks.
Trolley jacks also come with wheels so if you need to move it around, this is easily done. Bottle jacks have a smaller base and also do not have wheels. This makes them difficult to move around, and are unstable.
Bottle jacks are easier to store, however, since they don’t take up much space. They are also easier to carry around, but not easy to move when on the floor.
There are some clear differences between the two types of jacks, even though they perform the same function. Depending on which of these factors is more important for you, the type of hydraulic jack you go for may be different.
Since most people tend to have cars with lower clearance, trolley or floor jacks are much more common in automotive than bottle jacks.
About The Author
I've spent many years selling cars, working with auto detailers, mechanics, dealership service teams, quoting and researching car insurance, modding my own cars, and much more.Read More About Charles Redding