Fracture of piston teeth in AT pneumatic actuator
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As can be seen from the diagram, the outermost teeth of the piston often break; the material is cast aluminum, while the rod is made of nickel-plated alloy steel. It seems to be because there is no spring installed at the piston
It seems that this valve needs to be disassembled and cleaned before use,,,,, Isn’t this maintenance work too sloppy? Lol It must be cleaned thoroughly, and the lubricant used during reinstallation must be free of impurities and uncontaminated! ! !
Are the outermost teeth too thin, or is there sticking at the outermost teeth?
At first glance, it might be a problem with the material strength, but other issues could also be involved. 1. The strength of the material decreases during machining, and since the last tooth is located at the very edge of the entire piece of material, the situation may be even worse. 2. Problems with mechanical limits. Without appropriate mechanical limits, overtravel can occur either due to the force exerted by gas or by a spring; in the first case it is the struggle between air pressure and the force of the last tooth, while in the second case it is the collision between the two pistons driven by the spring. 3 Design Problems
The mechanical limit is a round nut with a larger and a smaller end; I really hadn’t noticed the limit mechanism before. Look back! But there is no spring on the piston! The 19 in Figure 2 does not exist in reality! Is it inappropriate?
Personally, I think this is possible, but in that case, it would be logical for the break to occur on the piston on the side without a spring. In practical terms, it seems that addressing the issue of mechanical limits is necessary. When used as a two-position actuator, once it reaches the end of its travel under air pressure, the mechanism’s limits will take over from the end rack to counteract the force exerted by the air pressure, thereby protecting the end rack. Without such limits, spring force would have to be used for balancing (protection), but whether spring force alone can suffice for this purpose is a question Looking at the picture, I think you might be a field service technician for the manufacturer, but given your mention that there are no springs on one side, I’m not so sure about that? Anyway, I still think there may be issues with the design of this product (1. material strength, 2. stroke design; it would be best if, throughout the entire stroke, the end rack is not under stress, or the end structure does not place the end rack at the very edge of the structure). Also, what’s the deal with no spring on this side?
To be honest, I don’t like this design with spring rebound, because one side of the spring is always in contact with the atmosphere; in humid environments, oxidation of the cylinder wall may occur.
It’s not that there’s no spring on one side; it’s that there are no springs on both pistons. The drawings I found online showed springs present. I am a technical staff member at a petrochemical company; all the clients are from that industry.
In that case, it means the cylinder heads with intake air on both sides of the piston, paired with two-position five-way solenoid valves, which is also a common configuration. In principle, this has nothing to do with damage to the rack. The rack at the edge is a weak point that needs protection (mechanical limits should be installed to replace this rack in order to counteract the pneumatic thrust). If this is not done, with the actuator remaining in this state for an extended period, the rack will be under continuous stress and is prone to problems