Insane Hydraulics
Bold and audacious blog about fluid power
This is an original Rexroth seal kit p/n R902166764 for A6VE55HZ3/63 plug-in hydraulic motors. As you can see - it's... minimalistic. It is composed of a shaft seal, nine o-rings, two sealing nuts, four metric plugs (2 x M10x1, 1 x M14x1.5, 1 x M18x1.5), and a washer (61.5 x 50.0 x 3.0). That's it.
Strangely enough, it was the "official" seal kit recommendation for the two A6VE55HZ3-63W-VZL22100B hydraulic motors I overhauled the other day. The "221" version carries a port plate with an integral counterbalance valve, two cross-port relief valves, and a brake release pressure-reducing valve:
The extra caps and plugs mean the R902166764 seal kit is not enough for the 22* versions, which is why I am adding a list of supplementary seals under the original kit content (and also some important notes below the table).
| Qty | Type | Size | Obs. |
| 1 | BAFSL 1SF FKM | 45x62x7/5 | Shaft seal, R909831179 |
| 1 | O-RING NBR70 | 132.94x3.53 | Case seal, R909085366 |
| 2 | Seal Nut | M10 | R909152426 |
| 3 | O-RING FKM90 | 9.25x1.78 | R909086487 |
| 3 | O-RING FKM90 | 15.54x2.62 | R909087891 |
| 1 | O-RING FKM90 | 17.12x2.62 | R909087938 |
| 1 | O-RING FKM90 | 7.65x1.78 | Brake release hole, R909085577 |
| 2 | O-RING FKM90 | 34.59x2.62 | Counterbalance valve, R909831230 |
| 2 | O-RING FKM90 | 28.24x2.62 | Check valves, R909153839 |
| 1 | O-RING FKM90 | 10.77x2.62 | Brake pressure reducing valve, R909086765 |
| 1 | O-RING FKM90 | 18.72x2.62 | Servo-cylinder plug, R909154235 |
| 1 | O-RING FKM90 | 15.3x2.2 | Pilot spool plug, R909830860 (see note below) |
| 2 | O-RING FKM90 | 23.47x2.62 | Cross-port relief valves |
| 2 | O-RING FKM90 | 17.0x2.4 | Cross-port relief valves |
| 4 | Backup ring | 18.0x22.0x1.2 | Cross-port relief valves |
| 1 | O-RING NBR70 | 151.99x3.53 | Flange o-ring |
The 15.3x2.2 o-ring is the "official" size for this pilot spool plug:
I didn't manage to order the 2.2 o-ring, but I got a 15x2.4 one (the black o-ring in the picture), and even this one felt thin for the cavity, so I ended up using one of the 15.5x2.62 o-rings included in the original kit (the green ones in the picture) - it fit quite well.
The two cross-port relief valves (R902603806, but the cartridges were actually marked as R930071620):
This is a special cavity designated by Rexroth as "FC." It uses an M28x1 thread and a nose diameter of 22mm. The seal kit for this cavity would be the RG22R2040540100 material no: R930077562.
I would say the larger o-ring could be the 23.47x2.62 (AS568-119), but the nose seal size is a harder to pick from "stadard stuff" because the cavity is 22x18x5 mm in size, so the common 2.62 mm cross section is a bit too wide for it. If I were to require a new combination of two backup rings and an o-ring for such a valve - I would go for something like 17.0x2.4 and two 18x22x1.2 backup rings. I included these seals in the table.