Hydraulic Fittings, Adaptors & Couplings
The adaptor that is holding your machine up, in stock on the van.
A significant share of the machines we are called to are not waiting on a hose. They are waiting on a five pound adaptor that nobody local has on the shelf.
Thread standards, and why they get muddled
Almost every mismatched fitting we see comes down to the same handful of confusions:
- BSP versus JIC. Similar sizes, entirely different sealing angles. BSP is a 60 degree cone, JIC is 37 degrees. Pull one up onto the other and it will seal for a while, then weep, then fail.
- BSP parallel versus BSP taper. Parallel seals on a bonded washer or an O-ring at the face. Taper seals on the thread. They are not interchangeable even though they will start to thread together.
- Metric versus BSP. Close enough in some sizes to feel right for two turns.
- ORFS. Seals on an O-ring in the face and needs the face undamaged. A nicked ORFS face will not seal at any torque.
If you are not certain what you have, send a photo of the sealing face rather than guessing. It takes a minute to identify and saves a wasted trip.
Quick-release couplings
Attachments live and die by their couplings. Two things go wrong repeatedly:
Undersizing. A coupling rated below the flow going through it gets hot, cooks its seals and starts weeping. If a coupling keeps failing on the same circuit, look at the flow before blaming the part.
Mixing types. Flat-face and poppet couplings do not connect to each other. Standardising a yard on one type is dull, cheap and removes a recurring problem.
Test points
If a machine has ever had an intermittent hydraulic fault, fitting a test point is worth doing while we are there. It costs very little and it means the next diagnosis is a gauge on a fitting rather than an hour of cracking joints to find out what pressure the system is actually making.
What is included
- BSP parallel and taper, JIC 37 degree, metric, ORFS, NPT and Komatsu.
- Flat-face and poppet quick-release couplings for attachments, with the correct sex and pressure rating.
- Test point fittings so pressure can be read next time without cracking a joint.
- Identification service: send us a photo of the thread and we will tell you what it is.
Common questions
Can you tell me what thread I have from a photo?
Often, yes, especially with something in frame for scale. BSP and JIC in particular get confused constantly because they look similar and are not remotely interchangeable. A photo of the sealing face is more useful than one of the outside of the fitting.
My new attachment will not couple to the machine. Can that be fixed?
Usually, with the right adaptor or by changing the couplings on one side. The thing to check first is the pressure and flow the attachment expects, because a coupling that physically fits is not the same as a hydraulic circuit that suits it.
Is it acceptable to use PTFE tape on hydraulic fittings?
On a tapered thread that seals on the thread itself, used sparingly, it is common practice. On a parallel thread that seals on an O-ring or a cone it does nothing useful, and shredded tape travelling into a valve block is a genuine cause of faults. If a parallel fitting is weeping, the seal or the face is the problem.
Why does my coupling leak only when the attachment is running?
Very often a flow or heat issue rather than the coupling. A quick-release coupling passing more flow than it is rated for gets hot and the seals go. Fitting a larger coupling is a real fix where undersizing is the cause.
Machine down? We can usually be with you the same day.
Tell us the machine, the hose and where you are. We will tell you honestly whether we can reach you and what it will cost before we set off.