Hydraulic cylinder properties, like stroke, force… and what material?
The planning started with data gathering. After I could start the drawing and planning.
I thought about the parts so many times and -as I thought- the easiest parts were the arm components (boom and arm). Based on pictures and specifications, I made a draft version booth of the arm parts. (I use CAD software for drawing and planning.)
During this work I had to calculate with the hydraulic parts, so my next thought was the hydraulic cylinder size. Ohh yes, this was a big task! The cylinders are one of the important part of the hydraulic system, so I wanted to plan strong cylinders, which are sized to the scaled model.
There are two “problems”:
– If the cylinder is enough little, the force will be lowest as the necessary.
– If the cylinder is enough strong, the dimension will bigger then the scaled one.
That was a big trip in the hydraulic and static world to find “gold way”.
Finally the fifth version has the right one.
To reach this version, I made an excel file with all arm dimensions (rotation fulcrums, suspension points…) and angles. If I change a parameter, workbook will be calculates the current forces in the working points.
Force calculator
Pressure and tube’s wall thickness were the most important things.
The tube and piston material is bronze because of the corrosion. The rod is a stainless steel.
I thought and read about the dimension and the construction…
I saw some cylinder which are frequently pop up on the web markets. The most simple structure contains just two or three o-rings, and an end-seal.
It’s OK, but the stability is in question… I’m not an expert, so this is just my opinion.
The hydraulic cylinder – in my case – is a comlex one. There have to be piston seals, rod and piston drivers, seals in the head and a dust extractor.
My piston diameter is 18mm, the tube wall thickness is 2mm and the rod diameter is 8mm. Naturally the force is depend from the pressure, so the maximum force is between 640N(OUT) and 510N(IN) if the pressure is 25Bar (2500000Pa)
If I can, I would like to use 35-40Bar pressure, because of my calculation the forces and moments will be enough big (really big) between this pressure level.
Now I search a proper hydraulic pump…
