70.1.2 REMOVAL AND REASSEMBLY OF THE PISTON AND LOCKING RING

REMOVAL

Locking ring 2

Stem 1 Piston 4

Nut 5 Screw 6 Piston 7

- Place the stem in a vice fitted with false jaws.

- Tighten so as to stop it turning.

- Loosen nut 5 (Fig. 1) and unscrew it completely using a box wrench. Or, depending on the version, remove locking screw 6 (Fig. 1) using a hexagonal wrench.

NOTE : Locking ring 6 (Fig. 1) is fitted using Loctite, then blocked by striking it with a chisel.

Locking ring 2

Piston 4 Stem 1

Locking ring 2

Stem 1

- Remove piston 4 (Fig. 2) by pulling it out manually or, depending on the version, by unscrewing piston 7 (Fig. 1) using a hook wrench.

- Remove locking ring 2 (Fig. 3) by sliding it along the stem.

INSPECTION

Comparator

- Check that the stem is straight over its whole length, using a comparator (Fig. 4).

- Check that the stem is not scaling, corroded or scratched.

Locking ring 2

- Reassemble locking ring 2 (Fig. 5) on stem 1 (Fig. 5).

- Reassemble piston 4 (Fig. 1) on the stem.

- Screw and lock nut 5(Fig. 1) using a box wrench and a torque wrench. See the table for the tightening torque (Fig. 6). Or, depending on the version, screw piston 7 (Fig. 1) using a spanner wrench (see tightening torque Fig. 6) and block it with locking screw 6 (Fig. 1).

NOTE : •

1. The locking screw should be fitted using Loctite 243, see section 70.1.5

2. Tightening torque for the screw : 20 Nm.

3. Strike with a chisel to drive the screw into the metal.

70.1.3 REMOVAL AND REASSEMBLY OF THE PISTON SEALS AND RING

NOTE !

Never use cutting or sharp tools (screw drivers, blades, etc.) when assembling and removing seals. Ensure that there are no chippings on the work bench.

REMOVAL

- Remove the piston seals and ring (Fig. 1 or 2).

- Take care not to damage the edges or the bottom of the grooves.

INSPECTION

- Degrease and clean the piston.

- Check that the groove bottoms and sides are smooth, and without scratches.

- There should be no extraneous bodies in the grooves.

REASSEMBLY

- Fit the seals and ring as in Fig. 1 or 2.

- When fitting the outside seals, open them sufficiently to slip them into the grooves while ensuring that they do not break.

- The inside ring should be fitted by hand.

70.1.4 REMOVAL AND REASSEMBLY OF THE SEALS AND RINGS ON THE LOCKING RING

NOTE !

Never use cutting or sharp tools (screw drivers, blades, etc.) when assembling and removing seals. Ensure that there are no chippings on the work bench.

REMOVAL

- Remove the locking ring seals and rings.

- Take care not to damage the edges or the bottom of the grooves.

INSPECTION

- Degrease and clean the locking ring.

- Check that the groove bottoms and sides are smooth, and without scratches.

- There should be no extraneous bodies in the grooves.

- Thread the bare ring on the stem and slide it over its whole length.

- The gap should not be excessive, but it should not grip either.

REASSEMBLY

- Fit the seals and rings as in Fig. 1. The lips of the stem seal should face the pressure side.

- When fitting the stem seal, first introduce it in the groove, holding it back either with your thumb or a bit (item 1) with no sharp edges (Fig. 2).

- Push it into the groove with the other hand or a smooth die (item 2) (Fig. 3). If the seal is too tight, dip it into hydraulic oil heated to 50°C.

- Fit scraper ring 4 (Fig. 1) using a plug and a mallet. O-rings 1 and 3 (Fig. 1) and extrusion proof ring 2 (Fig. 1) will be fitted by hand.

70.1.5 APPLICATION OF THE THREAD LOCKING MATERIAL

Characteristics

Light thread locking material (Loctite 222)

Application on the locking ring threads. Without activation agent

Use time ( Placing of the cylinder under pressure)

Medium thread locking material (Loctite 243)

Application on the M8 screws to lock the pistons. Without activation agent

REMOVAL

If the parts fitted with locking material cannot be removed using standard tools, we recommend heating the glued area to T = 250°C, preferably using a hot air pistol rather than a blow pipe.

REMARK

If the temperature is near 0°C, we recommend using a Loctite activation agent for the assembly, in addition, this will limit the polymerisation time.