Aftermarket Check Valve Outlet Fitting for Lincoln 504-30344-4
This page describes an aftermarket check valve outlet fitting that cross-references Lincoln part number 504-30344-4. The fitting is designed for use with SSV progressive metering devices and related blocks. Lincoln is a trademark of its respective owner. This is an aftermarket fitting, not manufactured, sponsored, or endorsed by Lincoln. Lincoln part numbers are for cross-reference identification only.
The part is a screw-in outlet fitting with an integrated check valve and a clamping ring for 6 mm tube. It is used at each lubrication point on a progressive divider block. The check valve controls the direction of lubricant leaving the metering device and entering the line to the bearing or point. This helps maintain line prime between lubrication cycles and reduces the chance of backfeed from one outlet into another. Confirm the thread size and outlet configuration before ordering if you are uncertain about your SSV block revision.
What the Fitting Does
The integrated check valve keeps lubricant from flowing back into the metering device after a cycle ends. When the pump stops and system pressure drops, the line between the fitting and the point remains filled. This is important for long lines, elevated lines, and points that must receive grease immediately on the next cycle. The check valve also helps prevent backfeed between outlets on the same divider block. Backfeed is a common cause of uneven metering and missed points on progressive lubrication systems.
Because flow is unidirectional, each outlet supplies only its intended point. The fitting is not a two-way valve and does not relieve pressure in reverse. The NBR seal helps contain lubricant at the thread interface, but the check function is mechanical. The clamping ring holds the 6 mm tube in place after insertion, allowing the line to remain connected under normal operating pressure and vibration. The M10 x 1 male thread screws into the standard female outlet port of an SSV divider block.
Specifications
The table below lists declared specifications for this aftermarket fitting. These values are based on the cross-reference part number and the rated SSV or SSVD metering device. Do not apply values from other thread sizes or fitting styles. Confirm the outlet size on SSVM blocks before ordering.
| Part number | 504-30344-4 |
| Type | Outlet screw-in fitting with integrated check valve |
| Clamping ring tube size | 6 mm OD |
| Thread | M10 x 1 male |
| Tube type | 6 mm OD plastic or metal tube |
| Body material | Steel body |
| Finish | Black chromated finish |
| Seal material | NBR seal |
| System max operating pressure | 350 bar (5,076 psi) per SSV/SSVD metering device rating |
| Operating temperature | -25 to +70 C |
| Flow direction | Unidirectional |
| Fits | SSV, SSV-E, SSVD metering devices |
Which Metering Devices It Fits
This fitting is designed to fit SSV, SSV-E, and SSVD progressive metering devices with M10 x 1 outlet ports. The outlet port thread and the 6 mm clamping ring match common progressive block configurations. Always check your block drawing or markings before installing. Some older or special blocks use different outlet geometries, even when the Lincoln base number appears similar.
For SSVM compatibility, confirm the outlet size on SSVM blocks before ordering, since some SSVM assemblies use a 4 mm fitting. Do not assume that the 6 mm fitting will work on every SSVM block. If your SSVM block has 4 mm outlet ports, this fitting is not correct. The SSV-E designation has the same outlet interface as SSV for most block widths, but you should still verify the outlet thread and tube size on your specific assembly. A useful reference for block identification and replacement details is the SSV divider valve replacement guide.
Installation Steps
Depressurize the lubrication system before removing any fitting from an SSV block. Residual pressure in the line can cause sudden discharge of grease. After the system is fully depressurized, remove the old outlet fitting and clean the port area. Hand-tighten the new fitting into the outlet port until the thread seats against the block. Then torque to the metering device specification. Do not use a value from this page because no torque value is declared here.
Insert the 6 mm tube fully into the clamping ring until it stops. The tube must be cut square and clean before insertion. A short or angled cut can prevent the ring from gripping correctly. After tightening, pull gently on the tube to confirm it does not move outward. Run a manual or test lubrication cycle and watch the outlet for leakage at the thread or the tube. Replace the fitting if the check valve does not hold prime after several cycles. For a broader view of progressive block operation and layout, see the progressive lubrication systems guide.
Tube Retention and Inspection
The clamping ring holds the 6 mm OD tube against the fitting body without a separate nut or ferrule arrangement. This setup is easy to connect and disconnect, but it requires re-inspection after pressure cycles. During initial operation, check each outlet for signs of tube creeping or ring loosening. If the tube moves under pressure, depressurize and reseat the tube. Do not reuse an old clamping ring after disassembly unless you are certain it is still round and undamaged.
Plastic tube can change slightly with temperature, so a connection made at -25 C may need a second check at +70 C. Metal tube is less affected by temperature but can deform if pulled sideways. The black chromated finish protects the steel body from superficial corrosion, but it does not change the clamping behavior. The seal material in the body should be compatible with common soap and oil lubricants. For details on different fitting types and how they affect line behavior, review the grease fitting types guide. If you need a quote for this part or a full set of outlets, contact the team with your metering device model.
Frequently Asked Questions
When do I need a check valve outlet instead of a plain outlet?
You need a check valve outlet when lubricant drains back after a cycle and the line loses prime. This is common on long lines, elevated points, or points with low backpressure.
Will this fitting fit my SSV block without modification?
It fits most SSV blocks with an M10 x 1 outlet port and a 6 mm tube connection. Check your block drawing and the existing fitting thread before ordering.
Does this fitting work on an SSVM block?
It depends on the SSVM outlet size. Confirm the outlet size on SSVM blocks before ordering, since some SSVM assemblies use a 4 mm fitting.
Can I use 6 mm plastic tube and 6 mm metal tube with the same ring?
The clamping ring accepts 6 mm OD plastic or metal tube. Cut the tube square and fully insert it into the ring.
Can I reuse the old clamping ring when I replace the fitting?
You can reuse it only if it is clean, round, and not deformed. Replace the ring after disassembly for reliable grip.
Does the check valve hold pressure in both directions?
No, the check valve is unidirectional and allows flow only from the metering device to the lubrication point. It does not hold pressure in both directions.
Is 350 bar the fitting rating or the system rating?
The 350 bar value is the system max operating pressure per the SSV and SSVD metering device rating. The fitting is used on systems rated to that pressure.
What is the thread size for the outlet fitting?
The thread size is M10 x 1 male, which screws into the metering device outlet port. The clamping ring accepts 6 mm OD tube.
Why do I need to re-inspect after pressure cycles?
The clamping ring can shift slightly after repeated pressure cycles, especially with temperature changes. Re-inspect each outlet to confirm the tube is still fully seated and the ring is tight.
Who builds this fitting, and how do I get a quotation?
IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, builds and supports every unit. Email inquiry@isohitech.com for specifications and a quotation.
Contact the team with your metering device model.
