Overhaul Kit Cord Cylinder Lely A3/A4 BLACK + Piston Rods

Overhaul Kit: Cord Cylinder BLACK + Piston Rods (Lely A3/A4)

This comprehensive overhaul kit is designed for the "New Type" Black Cord Cylinders used in Lely Astronaut A3 and A4 milking robots. Unlike a basic seal kit, this version includes both the internal seals and the replacement piston rods (short and long), ensuring a total restoration of the retraction mechanism.

Product Identification & Components

Why Replace the Piston Rods?

In many cases, simply replacing the rubber seals is not enough to fix a leaking or sticking cylinder.

• Surface Scoring: Over millions of cycles, fine grit can scratch the surface of the rods. These scratches act like "knives," quickly cutting through new seals and causing leaks to return within weeks.
• Bending: If a cow kicks a teat cup or the arm experiences a collision, the internal rods can suffer micro-bends that cause the cylinder to bind or "stutter."
• Pitting: Ammonia and moisture in the barn environment can cause pitting on the rods, which compromises the vacuum/air seal.

Installation Instructions

1. Safety First: Depressurize the pneumatic system and disconnect the 3-meter milk cup cords before disassembly.
2. Orientation: Note the positioning of the Short vs. Long rods during removal. Installing them in the wrong ports will prevent the teat cups from parking at the correct height.
3. Clean the Bore: Before inserting the new rods and seals, use a lint-free cloth to clean the inside of the black cylinder housing.
4. Lubrication: Apply a thin, even coat of the supplied pneumatic grease to the new rods and piston seals. Avoid over-greasing, as excess lubricant can clog the magnet valves (e.g., Festo 557649) downstream.

Technical Tip

If you are performing this overhaul, it is the perfect time to inspect the Retraction Cords (5.1004.2310.0). If the cords show any signs of fraying where they attach to these new piston rods, they should be replaced to prevent a snap shortly after your repair.