Tech Tip: The Ups and Downs of Jacks – UnderhoodService
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Tech Tip: The Ups and Downs of Jacks

If we were to start assigning personalities to tools in the shop, jacks would definitely be the Rodney Dangerfield of the automotive world. These tools are asked to lift things that weigh 100 times their own weight, we complain because they are too heavy, we keep them stuffed in corners and under workbenches when not using them, they are too short, too tall, not short enough, not tall enough. We don’t use them for weeks or months at a time and then complain if they are a little slow to react, make any funny noises or leak any fluid. Sheesh! Talk about no respect!

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By Muke DuBois
Contributing Writer

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The famous actor/comedian Rodney Dangerfield was well known for his routine about respect. You couldn’t watch him for more than a few minutes before you heard his signature line: “I can’t get NO respect!” If we were to start assigning personalities to tools in the shop, jacks would definitely be the Rodney Dangerfield of the automotive world. These tools are asked to lift things that weigh 100 times their own weight, we complain because they are too heavy, we keep them stuffed in corners and under workbenches when not using them, they are too short, too tall, not short enough, not tall enough. We don’t use them for weeks or months at a time and then complain if they are a little slow to react, make any funny noises or leak any fluid. Sheesh! Talk about no respect!

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Types of Jacks
The automotive repair business has been using jacks to repair cars and trucks for as long as there have been cars and trucks. The earliest jacks were mechanical devices based on variations of scissors. These jacks relied on a large screw combined with a scissors brace and the human strength of the user.

Scissors jacks are still in use today and are original equipment on most vehicles. The advantage of these jacks is that they require no outside power source, they are extremely light and they don’t rely on hydraulic fluid to work. The disadvantage of mechanical-style jacks is that they are too slow in most cases to be used in a professional shop situation. As we all know, time is money and it could take as much as five minutes using one of these jacks just to take a wheel off a vehicle!

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Generally speaking, jacks fall in to two main groups and then there are several sub types of jacks. Jacks are first and foremost either hydraulic or non-hydraulic. Hydraulic is loosely defined as combining or applying force in combination with a non-compressible fluid such as oil to do work. In almost all cases, force is either multiplied or divided in hydraulic systems. So in plain English, by taking a tool that can hold oil via tubing, pistons and chambers, and applying force, you can lift, move, push or pull things that would other wise be impossible to move with the same amount of force. Pretty cool!

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While you might think the discovery of hydraulics is a recent thing, the fact is that both the Chinese and the Greek cultures used hydraulics as early as 600 BC!

Hydraulic jacks come in both air-assisted and non-air-assisted. This is a process where the “force” or pressure that is applied to the fluid in the jack is air instead of a manual source of pressure using a lever or handle. By using air to apply this force, the jack pressure can be increased by many times. This is especially useful on larger capacity lifts and jacks that are used to lift heavy-duty equipment. If you plan on lifting big equipment or trucks frequently, it probably makes sense for you to invest in air-assisted jacks. These will generally be 25-50% more expensive than a non-air-assisted jack, but the extra capacity is well worth the cost.

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There are several different kinds of hydraulic jacks. There are bottle jacks, floor or service jacks, and specialty application jacks. In most cases, the job will determine what kind of jack you need to use. Factors such as clearance, weight of the item you need to lift, the surface you are working on, the availability of air and how long you need to lift the item will all affect your final choice.

Bottle Jacks
Bottle jacks are a good choice when you need a lot of lifting power, but don’t have a big or open working space. Bottle jacks are extremely powerful — pound for pound they’re probably the champions. Bottle jacks are little more than hydraulic rams with no frills. They are designed to sit where you put them and go up and down. There are no bells or whistles. While some have wheels on them, most don’t. There are single-stage jacks, (one piston) or multiple-stage (more than one piston). Multi-stage bottle jacks have higher capacity.

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Air-assisted or “air/over” bottle jacks are the undisputed heavy-weight champions of bottle jacks. These relatively compact jacks are capable of lifting weights as high as 100 tons! The disadvantage of bottle jacks is that they are not terribly mobile and generally have very small contact points. This is the part of the jack that actually touches the item you are lifting. The danger is that you can damage or destroy a part of the vehicle you are trying to lift if you aren’t careful about the spot you pick on the bottom of the vehicle you are lifting.

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Floor/Service Jacks
The terms “floor jack” and “service jack” are often used interchangeably. Both names make sense if you think about it. These jacks are used to service vehicles, and for us old guys, they were used at service stations!

They roll across the floor of the shop and are used to work on cars that are on the ground (floor). So whichever name you choose is probably OK. As the tonnage on these jacks goes up, it’s more likely you will hear them referred to as service jacks. This type of jack is offered in a wide range of capacities from as little as one-half ton up to as much as 100 tons for lifting really big stuff like military, industrial and agricultural equipment.

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Special Features/Application Floor Jacks
You NASCAR fans out there might recognize the date February 15, 1948. This was when the first sanctioned race in the new league was run at Daytona Beach, FL. As the new league started to gain momentum, racers started getting more serious about how they could gain competitive advantage. Early on, everyone figured out that races are won and lost in the pits. Shortly, guys started tinkering with the heaviest and slowest thing in a pit stop, the floor jack.

The advancements made on Sunday afternoons have helped improve the floor jacks we use today. Today there are floor jacks made specifically for racing that are able to lift a car in a few short pumps and weigh less than the wheel and tires of the early race cars. Using metals such as aluminum and alloy blends, these are not only extremely light, but exceptionally strong as well. The same features that make these jacks a good choice for the racecar driver make them a great choice for the technician and the DIY user as well. Nobody likes carrying a heavy jack and the improved speed to raise a car makes it beneficial to the professionals as well.

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There are two features to look for when thinking about time savings: first is: “pumps to load.” This means how many times you have to pump the jack to get it to touch the bottom of whatever you are raising. This is one of the biggest time killers when using a floor jack. The latest jacks have special valving that raises the lifting saddle in just a few strokes. Some high-end jacks will reach the load in one to three pumps as opposed to 15 to 20 on the older-style jacks.

The other feature, which is just as important, is the number of pumps required to lift the jack to its highest point. Again, by using special valves and compound action, the high-tech racing jacks can lift a car in just a few strokes. If you are a racing fan, you know that every tenth of a second costs money, it’s like that with floor jacks too! For every stroke reduction and time savings offered, you can expect to pay more for the jack.

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Some models of floor jacks now have two main cylinders instead of the traditional single ram. This effectively doubles the amount of fluid that can be pumped on each stroke, which cuts the number of strokes required. Again, expect to pay more for double ram jacks, but the time savings may be worth it to you.

Specifications/Construction Details
When deciding on a jack, there are several specifications and measurements you want to think about. The obvious is capacity. This is the first number that manufacturers will always tell you. Expressed in tons, this will usually be a whole number. Like any numbers game, always check the fine print. Sometimes specs will get rounded up. This usually is only a problem on non-name-brand economy products. The larger suppliers are very conservative and will usually understate, not overstate, the capacity of their lifting equipment. It’s just not worth it to a good manufacturer to take the risk and fudge the capacity of their jacks. If someone was to ever get hurt and it turned out that the supplier had misstated capacity, it could cost the company everything.

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In the last several years, the low height measurement of jacks has become more important. This is the height of the jack with the lifting saddle in the down position. As low rider vehicles became more and more popular in the early ’90s, low height measurement became more critical. As is always the case, street designs found their way into the OEMs, and now it’s common to see brand new cars with 50 series tires and ground effects. For that reason, you need to pay attention to the low height of that next potential jack.

The high height is not critical to everyone, but you should think about it if you work on trucks. Even stock two-wheel-drive trucks are now coming with 16” wheels that can make them challenging to lift with some jacks.

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Another detail to think about is handle configuration. Handles for floor jacks come in either one- or two-piece designs. Manufacturers like to ship in two pieces because they can use a smaller box and save shipping cost. Higher quality jacks tend to use the one-piece design; it seems to hold up better and there’s no chance of the handle ever coming apart!
As you can see, there is quite a bit to think about when deciding which jack you are going to buy.

One thing is for sure, if you spend some time thinking about those things before making your buying decision, you won’t be saying you can’t get no respect!

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