What is the purpose of a tail rod in a reciprocating compressor?
Thread Content
Our new installation has two compressors with tail rods, while the two three-stage compressors nearby do not have tail rods. Search for the keyword \"tail rod\" on the forum; there are replies saying that a tail rod is added only when the reverse angle is insufficient. What is a reverse angle? Is it the amplitude of up and down movement of the connecting rod per rotation of the crankshaft? However, the crankshaft eccentricity for both sets of different compressors is 110, the diameters of the rod ends are the same, and the center distance is also 460. This reverse angle should be the same, right?
2D small compressor, used for fresh hydrogen or recycled hydrogen, oil-free lubrication.
The reverse angle is the constant angle maintained when the piston rod is under tension or compression (tension and compression must alternate within a 360-degree range) to ensure that lubricant can flow into the side that is not under stress. If it is under tension or compression continuously, the side under stress will never receive lubrication. Final wear failure.
First of all, it is specified in API618. Compressors with tail rods must be confirmed by the user. The reason is that the capacity is too small; in a properly designed design, there is no reverse angle at the crosshead pin (over 360 degrees, the crosshead pin is subjected to compression or tension, and the duration of this compression or tension – which can be considered as time – constitutes the reverse angle). Additionally, the lubrication is insufficient. A rod with a tail is the last resort; it introduces an additional point of high-pressure leakage and sealing, and there are more support points for the piston rod shaft system, requiring higher installation precision.