Piston Spring Pressure Disc 20mm

Pressure disc 40510 with a diameter of 20mm is a thrust element of the piston spring assembly in the Kranzle pressure washer pump. It sits between the piston spring and the piston surface or its guide, and distributes spring load evenly across that area.

Application

The disc is mounted in the piston cylinder of the pump – on one or both sides of the piston spring, depending on the head design. It increases the contact area between the spring and the piston or thrust seat, preventing stress concentration at the point where the central spring coil contacts the piston material. It operates continuously during each piston stroke.

Replaced during pump head service – when dismantling the piston assembly, replacing seals or the piston spring.

Symptoms – when to replace

• Visible indentation or wear on the disc face – a mark from a spring coil indicating pressure concentration at a single point.
• The disc sits at an angle in the seat or is noticeably loose – the spring operates at an angle and the load on the piston is asymmetric.
• Cracking or chipping of the edge – initiated by corrosion or stress under intensive use.
• Seizure or corrosion preventing the disc from seating flat in the guide – the disc does not sit perpendicular to the piston axis.

How to select the right part

The primary selection parameters are the 20mm diameter and reference number 40510. Before ordering, measure the removed disc with a calliper – both diameter and thickness. A disc that is too small does not cover a sufficient surface area; one that is too large will not fit in the cylinder or will obstruct piston movement.

When replacing the disc, assess the condition of the associated piston spring at the same time – both components operate under the same conditions and wear at the same rate. With the head already open, replacing both components during a single disassembly is more practical than returning to the pump a few months later.

[faq]

What happens when one disc in a multi-cylinder pump is 20mm and the others are 18mm – is this a significant error?|Yes. A disc of a different diameter alters the spring operating conditions in that cylinder – the load on the piston differs from the other cylinders. In a multi-cylinder pump, mismatched discs result in asymmetric piston operation and can cause subtle pressure pulsation. When dismantling the head, always check the discs in all cylinders and order a complete set of identical components, not just the damaged one.

How to check disc thickness during an inspection, and when is thickness a critical parameter?|Measure the thickness with a calliper at several points – a variation of more than 0.1–0.2mm between points indicates uneven wear or deformation. Disc thickness determines the working length of the spring once installed – a thinner disc reduces the spring pre-compression and lowers the piston return force. When ordering a replacement, measure the thickness of the removed disc and compare with the new one – discs of the same reference number should have identical thickness.

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