My HW90 ram pressure gage started to bind and got progressively worse until it froze.
Normal operation of the Weihrauch gage is to press down on the top of the gage. That telescopes the gage closed and forces a small pin out of the end, which contacts the schrader valve in the back of the piston, letting air pass from the piston to the gage and you get a reading. The pressure then kicks the gage back to full extension.
In this case the gage head would depress but would not come back up, even when reading a fully charged ram.
To disassemble, drive out the retaining spring pin (see arrow). Use a punch with a clean, sharp edged, flat tip. The gage just pulls apart.
The problem was a burr on the stem. It was easy to remove with a fine file and some 400 grit paper. It may have been caused during assembly; the retaining pin caught the edge of the stem and created a burr.
The gage works perfectly after removing the burr. But without the internal friction of the burr, the gage springs out almost too easily. I toyed with the idea of applying a knurl to the stem to increase the diameter and friction a little. LOL.
Here are the o-ring measurements.
Large o-ring. ID = 5.5mm. Thickness = 1.75mm.
Small o-ring: ID = 4.0mm. Thickness = 0.75mm.
Normal operation of the Weihrauch gage is to press down on the top of the gage. That telescopes the gage closed and forces a small pin out of the end, which contacts the schrader valve in the back of the piston, letting air pass from the piston to the gage and you get a reading. The pressure then kicks the gage back to full extension.
In this case the gage head would depress but would not come back up, even when reading a fully charged ram.
To disassemble, drive out the retaining spring pin (see arrow). Use a punch with a clean, sharp edged, flat tip. The gage just pulls apart.
The problem was a burr on the stem. It was easy to remove with a fine file and some 400 grit paper. It may have been caused during assembly; the retaining pin caught the edge of the stem and created a burr.
The gage works perfectly after removing the burr. But without the internal friction of the burr, the gage springs out almost too easily. I toyed with the idea of applying a knurl to the stem to increase the diameter and friction a little. LOL.
Here are the o-ring measurements.
Large o-ring. ID = 5.5mm. Thickness = 1.75mm.
Small o-ring: ID = 4.0mm. Thickness = 0.75mm.