The LCN 4030-3048 is the OEM head and tube assembly for the LCN 4030 Series door closer - Item 8 in the LCN Closers and Automatic Operators Parts Manual (doc 111167). This is the hydraulic body itself. Not the arm, not the cover, not the shoe. The cylinder assembly has the fluid, the spring, the piston, the pinion, and all the adjustment valves. When that assembly fails, this is what you replace. Finish must be specified at order.

One thing to confirm before ordering: the 4030-3048 is the standard version. If the installed closer uses a long hold-open arm (4030-3049L), the correct head and tube is the 4030-3048L - a different, longer assembly. They're not interchangeable. The standard arm gets 4030-3048. Long hold-open arm gets 4030-3048L.

What's Inside the Head and Tube Assembly

The "head" is the end cap where the hydraulic adjustment valves live - sweep speed, latch speed, and backcheck. Those three valves are what the service technician turns to calibrate the closing cycle on any LCN closer.

Sweep speed controls how fast the door moves through the main arc of closing, from full open down to about 10 degrees from shut. Latch speed takes over for that last 10-degree snap into the frame. Backcheck is the resistance the closer applies near full-open to cushion the door before it hits the stop. When any of these valves strip or won't hold a setting, the head assembly is compromised and the whole unit needs replacing.

The "tube" is the cylinder body where the fluid, piston, and spring sit. Opening the door compresses the spring and pushes the piston through the hydraulic fluid. The fluid has to work through the adjustment valves - that's what slows the door down on close. When the spring breaks or the fluid leaks out, the door either slams or doesn't close at all.

The cast iron body on the 4030 houses all of this. Cast iron because it handles thermal expansion better than zinc or aluminum, and because it holds up in high-cycle environments where lighter materials would wear at the pinion bore. The piston inside is 1-1/8" diameter. The pinion journal is 1/2" diameter, single, heat-treated. LCN uses a full complement bearing around that pinion - every roller in the set is in contact, so the load distributes evenly across the full bearing race rather than concentrating at a few contact points. That's what gives these closers their cycle life in moderate to heavy traffic applications.

LCN 4030 Series: What You're Working With

The 4030 is LCN's surface-mounted closer for moderate traffic doors. Non-sized cylinder (the 4031) adjusts size 1 through 4 - exterior doors up to 36" wide, interior doors up to 48". It mounts three ways: hinge pull side, push side top jamb, and push side parallel arm. Non-handed, so it works on left and right swing without ordering differently.

ANSI A156.4 Grade 1 certified. UL and cUL are listed for self-closing doors. ADA compliant - less than 5 lbs of opening force on a 36" door is achievable with this series.

The 4030 Parts Diagram: Where 4030-3048 Sits

In the LCN 4030 parts diagram, the head and tube assembly (Item 8, 4030-3048) is what every arm attaches to. The regular arm (4030-3077), H arm (4030-3049), light duty arm (4030-3077LD), long arm (4030-3077L), and the arm-and-forearm assembly (4030-77) all drive the pinion on this assembly. The arm screws (4030-159 and 4030-83) secure the arm to the pinion. Rod and shoe (4030-79) handles the track arm slide.

When you're replacing the head and tube, check the existing arm and shoe before ordering new ones. If they're not damaged, they reinstall on the new assembly without issue.