Insane Hydraulics
Bold and audacious blog about fluid power
Here you have a Rexroth A6VE55HZ3/63W-VZL22100B plug-in hydraulic motor. This model is special because it uses a port plate with an integrated counterbalance valve, two cross-port relief valves, and a brake release valve that supplies reduced pilot pressure through an internal channel straight to the hole located on the face of the front flange:
The shop I currently operate in is tiny, and we don't have a "proper" hydraulic motor bench that can interface to a motor and brake it, so when I want to test an overhauled unit, I usually just connect it to our pressure/flow bench and run it to check for external leaks, control function, and abnormal noise. As you can imagine, the open and actively pressurized hole on the face of the mounting flange poses an additional challenge when you want to take such a motor "for a quick run." So, in this post, I want to showcase an accessory for plugging and reading pressure in the flange-face-located brake release port of a plug-in hydraulic motor.
The idea is to have a plate that can be compressed against the flange face with a bolt through one of the mounting holes, and then have a threaded hole in it aligned with the brake release hole so that a test fitting can be threaded in and pressed against the face with a copper or a USIT washer under it for a sealed connection. All you need to make this plate is a sliver of 10-mm steel sheet and basic metalworking skills. Let me show you what I mean. First - you make a paper stencil for the three holes that the plate will require:
The 17-mm hole is aligned with the mounting hole of the flange, the 11.8-mm hole is aligned with the brake-release hole and tapped with 1/4'' BSPP thread (because I have tons of Minimess 1/4''G test fittings), and the 6.8-mm hole is located right next to the flange edge and is tapped with M8 thread. This third hole is for a bolt that will be inserted under the plate to keep it compressed against the flange. It is not mandatory because the 10 mm thick plate is already rigid enough by itself, and the reduced pressure in the brake port is relatively low - about 25 bar - so the compressing force required for a sealed connection is not that big, but I still made it for additional safety.
Now - all you need to do is place the plate on the flange face, align the brake release hole with the threaded hole, tighten the M16 bolt and the safety M8 bolt from the other side (I used a random M8 bolf with a couple of washers welded to its head for an "extra-wide" bite).
And for the sealed connection - you drop a washer seal of your liking into the threaded hole - in my case, it's an M6 USIT seal that perfectly aligns inside the G 1/4'' hole, and then compress it with a test fitting screwed on top of it, like so:
And now you can run all your "wet tests" at will:
And there you have it, folks - another piece of scrap metal just got transformed into a useful test accessory!