Stainless hydraulic fittings made to drawing for defense equipment

Where are hydraulic fittings used in defense applications?

• Mobile hydraulic systems: cylinder and motor connections on vehicle-mounted lifting, ramp, hatch, outrigger and crane systems.
• Compact power units: tight-angle elbows, block connections and SAE flanges in pump, valve block and tank assemblies fitted into limited space.
• Maintenance and test benches: adapters that are frequently connected and disconnected on benches where hydraulic components undergo post-maintenance function and leak tests.
• Ground and support equipment: hydraulic lifting, handling and maintenance equipment used in the field.
• Naval platforms: deck and engine room hydraulics exposed to salt-laden environments.

From technical drawing to series production

In defense projects, the part definition usually comes with the customer's technical drawing. Before production, material grade, connection standard, critical tolerances and surface requirements are confirmed; no dimension that remains unclear is released to production.

1. Part definition: The material, the current revision of the technical drawing, the thread standard and critical dimensions are clarified before work begins.
2. Machining plan: Bore, wrench flat, thread and sealing surface operations are planned around the part's fixturing and inspection setup.
3. First article approval: The first part produced goes through dimensional inspection and is submitted for approval; series production starts after this approval.
4. Series production and final inspection: Thread fit, diameter, surface and sealing area are checked before the part is prepared for shipment.

At raw material receiving, surface, diameter and batch information are checked; a traceable batch system makes it possible to track which raw material batch a part was made from. Any additional documentation, testing or inspection requirements should be stated in writing at the quotation stage. When the technical drawing is revised, the batch from which the change applies should also be clarified in writing; two different revisions of the same part number can cause confusion in the field.

Why is dimensional repeatability critical?

In mobile systems, spare parts are often fitted in the field without re-measuring. If the length or sealing cone of an adapter in one batch differs from the previous batch, the hose route changes, assembly is forced and a leak risk arises. CNC machining makes it possible to produce the same geometry throughout a series with the same program and fixturing; dimensional inspection verifies that repeatability in every batch.

Connection standards and selection criteria

The standard used often depends on the origin of the equipment: European systems more commonly use metric 24° cone bite-type fittings and BSP ports, while US systems more often use JIC/UNF and SAE flanges. The main criteria considered in selection:

In mobile systems operating under vibration and shock, the way a connection is supported matters as much as the connection itself. Long tube runs should be clamped at suitable intervals, hoses rather than tubes should be used between sections that move relative to each other, and points where a hose rubs against the body should be protected. Overtightening fittings is as problematic as leaving them loose; the sealing surface can be damaged.

Custom geometry in compact power units

In power units installed inside a vehicle or a confined cabinet, standard elbows and adapters often do not fit. In such cases, custom transition fittings that combine two connections in a single piece, adapters with an outlet at a different angle, or blocks with SAE flange connections are designed. Production becomes more predictable when port size, connection orientation and installation clearance are defined on the same technical drawing. The assembly sequence should also be planned: if a connection can no longer be reached with a wrench once the adjacent part has been installed, this should be noted on the drawing or the part geometry adjusted accordingly. Fewer parts also mean fewer potential leak points.

Maintenance and spare parts continuity

Defense systems remain in service for many years; during that time, the original supplier of some fittings may change or a part may be discontinued. Reproduction from samples or technical drawings ensures spare parts continuity throughout the platform's service life. Planning spare sets for adapters that are frequently removed and refitted on maintenance benches keeps the test schedule on track.

Lead time

After technical drawing approval, custom-size and project manufacturing is scheduled within 10-20 business days on average. Standard catalog products are prepared within 1-3 business days depending on stock availability, and standard production items within 5-10 business days. Parts are packed separately by size and order group, with protective caps on threads and ports. Please state your drawing sharing and confidentiality requirements at the quotation stage.