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Hydraulic Cylinder Dangers

Dangers Associated with Hydraulic Cylinders

Although hydraulic cylinders are a necessary and integral part of industry, there some very real dangers associated with them that could become fatal. Not least of which is pressure multiplication. Pressure multiplication in hydraulic cylinders The force applied in a hydraulic cylinder is calculated with the equation (F = P * A). In a double acting cylinder(one that is powered both in and out) the area of the piston on the bottom or cap end side is much larger than the area of the piston on the rod side. This causes an unequal pressure difference on either side because, on the rod side, the smaller area has to have more pressure pushing on it to keep the piston from being moved by the pressure pushing on the larger area of the piston on the other side. If the effective surface area of the piston on the rod side of the cylinder has half the area of that on the piston side, it will produce half the force on the piston side for the same amount of pressure. Getting back to our equation, Force = Pressure multiplied by effective piston surface Area using a 3” piston on a 2” rod and a pressure of 2000psi we get a force of 14000lb on the piston side and only 8000lb on the rod side. If, for any reason, the piston side of a double-acting cylinder is pressurized and at the same time fluid is blocked on the rod side, pressure will increase (multiply) in the rod side of the cylinder until the forces become balanced or the cylinder fails catastrophically. When we transpose the equation above to calculate the pressure produced, we get P = F/A, Pressure = Force divided by piston surface Area. Applying this to our 3” piston 2” rod and 2000psi pressure, on the piston side we get:- P = 14000 / 4 which equals 3500 psi. Considerably more than the pressure on the other side. If we take the main relief pressure of most systems of 2800psi, then our pressure goes to a staggering 4900psi which is definitely not good for your system. Depending on where the hydraulic fluid is blocked, this could result in anything from a blown hose to blowing the gland seals out or even catastrophic damage to the cylinder. Remember, at Central Qld Hydraulics, we take any old cylinders that are preserved well, replace their damaged parts to make them go on doing their outstanding work as new cylinders.
Phone us
Call us today for more information 07 4952 5621
cyl1 cyl2 cyl3 excavator
Surface area 7 inch²
Surface area 4 inch²
Cross sectional surface area 3 inch²
2000psi
Cylinder test
Find us here...
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CENTRAL QUEENSLAND HYDRAULICS

As well as selling new parts and components, we also service and rebuild all the products we sell. We have a comprehensive spare parts and exchange parts service. And all work is guaranteed.
We supply all filters from any manufacturer We have a comprehensive filter service. And all work is guaranteed.
All types of hydraulic tooling. Hydraulic cylinders of all shapes and sizes. Hydraulic fittings and hoses.
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Home Products Filtration Service & Repairs Hire Distributorships Quality & Safety Profile Contact Us headerline Flare
Copyright © 2013, Central Queensland Hydraulics Pty.Ltd. - Contact our Webmaster
Oil drop

Hydraulic Cylinder Dangers

Dangers Associated with Hydraulic Cylinders

Although hydraulic cylinders are a necessary and integral part of industry, there some very real dangers associated with them that could become fatal. Not least of which is pressure intensification.

Pressure intensification in hydraulic cylinders

The force applied in a hydraulic cylinder is calculated with the equation (F = P * A). In a double acting cylinder(one that is powered both in and out) the area of the piston on the bottom or cap end side is much larger than the area of the piston on the rod side. This causes an unequal pressure difference on either side because, on the rod side, the smaller area has to have more pressure pushing on it to keep the piston from being moved by the pressure pushing on the larger area of the piston on the other side. If the effective surface area of the piston on the rod side of the cylinder has half the area of that on the piston side, it will produce half the force on the piston side for the same amount of pressure. Getting back to our equation, Force = Pressure multiplied by effective piston surface Area using a 3” piston on a 2” rod and a pressure of 2000psi we get a force of 14000lb on the piston side and only 8000lb on the rod side. If, for any reason, the piston side of a double-acting cylinder is pressurized and at the same time fluid is blocked on the rod side, pressure will increase (intensify) in the rod side of the cylinder until the forces become balanced or the cylinder fails catastrophically. When we transpose the equation above to calculate the pressure produced, we get P = F/A, Pressure = Force divided by piston surface Area. Applying this to our 3” piston 2” rod and 2000psi pressure, on the piston side we get:- P = 14000 / 4 which equals 3500 psi. Considerably more than the pressure on the other side. If we take the main relief pressure of most systems of 2800psi, then our pressure goes to a staggering 4900psi which is definitely not good for your system. Depending on where the hydraulic fluid is blocked, this could result in anything from a blown hose to blowing the gland seals out or even catastrophic damage to the cylinder. Remember, at Central Qld Hydraulics, we take any old cylinders that are preserved well, replace their damaged parts to make them go on doing their outstanding work as new cylinders.
Phone us
Call us today for more information 07 4952 5621
cyl1 cyl2 cyl3 excavator
Surface area 7 inch²
Surface area 4 inch²
Cross sectional surface area 3 inch²
2000psi
Cylinder test
Find us here...
Danger flag