How Do Office Chair Cylinders Work?
Placed at the bottom of the under the seat cushion, an office chair cylinder allows for quick and easy adjustment through a specific height range.
They do this by taking the pressure power of compressed gas and forcing it through a chamber that moves the seat to the desired location.
By pressing the lever on the chair, the gas is pushed in and out of the chamber, this force enables the office chair's seats to raise or lower down.
In this article, you will get to know:
- The different types of office chair cylinders
- Their different parts and functions
- Things to consider while installing
- How to replace them.
What are the different types of office chair cylinders?
There are two main types of office chair cylinders: pneumatic and hydraulic.
Most office chairs use pneumatic cylinders and even though they are similar, there are some key differences in the way they work.
1. Pneumatic cylinders:
Pneumatic cylinders work similarly to a bicycle pump, but instead of a simple air chamber, the pneumatic cylinder chamber is filled with pressurized nitrogen.
With these chambers being completely sealed and the high pressure stuck in there.
You can release this pressure through a gas spring; a moving part of the cylinder locked in place.
By pulling the lever, the gas spring will rise, pushing the chair upwards.
To sink the chair, you just need to unlock the spring and sit on the chair, the weight of your body will push the chair down.
But if the spring is locked in place, no amount of weight will affect it and the chair will remain in its place.
2. Hydraulic cylinder:
The hydraulic cylinder works in the same way, except for some details, such as:
- There are two pressure chambers instead of one.
- Filled with fluids instead of nitrogen.
Both chambers are connected at the bottom, one filled with high-pressure incompressible oil, and the other containing an expandable piston.
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When the lever is lifted, the valve separating the two chambers opens, allowing the fluid to enter the piston-containing chamber, the pressure of which forces the piston upwards.
Since the incompressible oil is strong enough to lift the piston, it also lifts the chair seat.
Just like in the pneumatic cylinder, the seat does not lower on its own and only does so when you pull the lever and put weight on it.
This is because they are single-acting cylinders.
Doing this will pull the piston downwards and also force the incompressible oil back in its chamber through the valve.
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What are the different parts of a gas cylinder?
Gas cylinders are seen in almost all office chairs, where the bottom goes into the wheelbase, and the top is inserted beneath the seat.
Then you can raise and lower your seat with a flick of a lever, situated at the side of the seat.
This makes it easy to adjust the chair height relative to your desk.
The standard gas cylinder is mainly comprised of the following parts:
The standpipe:
This is the main column that connects to the base of the chair, the end inserted into the wheelbase.
Although the length of the column may vary from chair to chair, the standard diameter for the most column is 2.
Piston:
This is usually a 1.1-inch diameter that connects to the base of the seat and is the part that raises and lowers to adjust the chair height.
Actuator:
This is the button that sits atop the piston that gets pushed to stimulate the lowering and raising of the chair.
Dust cover:
It is the plastic dust protector that is placed over the main column.
Retainer clip:
The tiny clip at the bottom of the piston that stops it from sliding out of the main column is called the retainer clip.
Often when buying an office chair the question that is asked is ‘what is your stroke?’.
And this, when simply put, means how much you want to be able to raise or lower your chair.
For example, according to office chair picks, the most common is the 4 stroke chair cylinder.
Can office chair cylinders become defective?
It is important to consider the weight capacity limits of your chair when buying a cylinder, with most standard chairs being able to bear the weight of about 250 lbs.
If your office chair sinks whenever you sit on it, you either bought the wrong weight capacity cylinder, or your cylinder has become defective.
If the cylinder can no longer hold your weight, this could be for a couple of reasons.
First of all, there could be a leak from a hole somewhere in the cylinder, causing the nitrogen or the oil to escape.
On the other hand, it could be that the mechanics happening in the chambers have worn out.
Due to this, the cylinder becomes too weak to hold the piston in place anymore, hence why your chair sinks whenever you sit on it.
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How to remove and replace office chair cylinders?
To revive your old office chair or fix it, you will first need to remove the defective cylinder.
Here is a video showing how to remove the old cylinder:
To do that, tip the chair over to access the wheelbase, then with a hammer, start tapping around the edge of the bottom of the cylinder.
Keep doing that until you have loosened it enough to pull the column over the base.
This releases the piston and you are left with an empty cylinder column stuck to the wheelbase.
Turning the wheelbase upside down, continue hammering the end of the column through until it is free.
To remove the piston head from the seat base, tap around the edge of its top with a rubber mallet to loosen it.
Once loosened you will be able to detach it from the base.
When finding the replacement, it is important to have it at the same diameter and length as the previous cylinder.
Consider weight capacity and check if the cylinder is rotating or non-rotating to meet the needs of your chair.
