Kinshofer KM602 / KM622 Valve Stem Adapter – Machined From Solid Hex Bar

A Kinshofer valve stem adapter connects the hydraulic tube to the load-holding and flow-control valve block on a Kinshofer KM602 or KM622 grab bucket cylinder. Simply Welding machined a replacement valve stem adapter for a Kinshofer grab bucket cylinder from solid hexagonal bar in our workshop, and we always keep Kinshofer valve stem adapters in stock, ready for same-day dispatch or fitting.

Job Description

We machined a valve stem adapter to bridge the hydraulic tube and the load-holding and flow-control valve block on a Kinshofer grab bucket cylinder.

Material Used

24mm hexagonal solid steel bar.

Operation One – Cutting and Facing

The hexagonal bar was cut to approximate length, set in the lathe and both ends were faced.

Operation Two – Turning the Threaded End

We turned the threaded end down to nominal size, leaving a landing flange to face-seal with a Dowty (bonded) washer. A thread relief was machined, a hole was drilled through the centre for oil flow, and all sharp edges were chamfered.

Operation Three – Machining the Valve Stem

The part was turned round in the lathe chuck and set to run true using a dial test indicator (DTI). We then machined the valve stem, the end that inserts into the bottom of the valve block, to the set diameter and length, and chamfered the port inlet and outlet.

Operation Four – Single-Point Thread Cutting

The part was turned round again and re-checked for runout. Once it was within tolerance, the BSP (British Standard Pipe) thread was single-point cut on the lathe.

Final Prep

All dimensions were checked, and the port inlet and outlet were polished to give a good seal against the lip seal in the valve block.

Result

The adapter fitted first time and the cylinder was back in service the same day.

Frequently Asked Questions

Why does the joint between the valve stem and valve block leak?

A leak at this joint on a Kinshofer grab bucket cylinder is usually caused by one of two things. Either the seal in the valve block has deteriorated, or the wall of the valve stem adapter has worn thin.

Do you keep Kinshofer valve stem adapters in stock?

Yes. We always keep Kinshofer KM602 and KM622 valve stem adapters in stock, so a leaking grab bucket cylinder can be back at work quickly.

What thread is on a Kinshofer valve stem adapter?

The adapter has a BSP (British Standard Pipe) thread, which was single-point cut on the lathe after the part had been re-checked for runout. The threaded end has a landing flange that face-seals with a Dowty (bonded) washer.

Why are the port inlet and outlet polished?

The valve stem end of the adapter inserts into the valve block and seals against a lip seal. Polishing the port inlet and outlet gives a good seal against that lip seal, helping to stop leaks at the joint.

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Need a hydraulic adapter or one-off fitting made? Call 07747 682451 or send us some photos via WhatsApp.