Hydraulic Struts - Basic Principals

I thought that this month I would take the opportunity to go back to basics and give a brief insight into how Groundforce propriety equipment operates and to try and explain what is actually going on within the struts when you get to work on the hand pump, or when you simply flick the lever on the labour saving motorised pump. The best way to explain this is to firstly show you a 3D representation of what it looks like on the inside of one of our high capacity double acting struts. Most of our hydraulic rams have 1.0m of stroke (hydraulic adjustment). As shown above, the ram itself is housed within the inner sleeve section of the strut casing whilst the piston rod is connected to the outer sleeve which is free to slide along the innersleeve as the ram is pumped in or out. In order to pump out, or extend the length of the strut, hydraulic fluid is pumped into the full bore side of the piston (shown in red). This causes the piston to move from left to right as you look at the sketch above which in turn causes fluid to be displaced from the area behind the piston or annulus side (shown in blue) back into the pump reservoir, and since this is connected to the outer sleeve of the strut, causes the strut to increase in length. To get the strut to retract back in it is simply a case of reversing the flow on the pump. To (hopefully) simplify this, I have shown two schematic circuit diagrams below, one for extend and one for retract.