UNION

738 034 20 FITTING is one of those bits that just connects things up, usually hydraulic lines or sometimes air, depending on where it’s fitted on the rig. It’s not fancy, but it’s crucial for getting fluid or air from point A to point B without a mess. Think about your feed cylinder lines or even some of the smaller hammer circuits; this UNION makes sure that connection holds tight under pressure, letting the system do its job without blowing apart. It’s basically a reliable junction point.

When these start going bad, you’ll usually notice it pretty quick. The most common thing is a weep or a full-blown leak. If it’s on a hydraulic line, you’ll see oil around the fitting, and depending on the pressure, it might just be a slow drip or a steady stream. That means pressure loss in that circuit, which can lead to sluggish functions, maybe a bit of drift in your feed, or just generally inconsistent operation. Sometimes, if it’s a swivel type, you might feel some binding or resistance in the connected component, but typically, it’s the leak that screams for attention.

Replacing one of these isn't usually a huge job, but you gotta make sure you clean the area thoroughly before you put the new one in. Any grit or old seal material left behind can mess up the new seal and you’ll be doing the job twice. Always check the threads on both ends – the UNION itself and whatever it’s screwing into – for damage. A common mistake is overtightening, which can strip threads or deform the sealing surface, so get the torque right. And don't forget to inspect the mating surfaces for scoring or corrosion; sometimes the problem isn't the UNION, but what it's connecting to.