Expansion Spring Ring 20mm

The 20 mm expansion spring ring is a service component used in a high-pressure pump assembly, acting as a spring/expanding element within the installation system. In repair practice it affects correct positioning and cooperation of parts inside the pump section, which is why it matters during refurbishments and overhauls.

MPN / reference: 40021
Weight: 0.001 kg
Dimensions / size: 25×4×25

APPLICATION

Used in pump and pressure washer service work, including:

• pump refurbishment during Kränzle pressure washer repair,
• replacing spring/expanding elements in the pump section after disassembly,
• restoring correct seating of parts in the pump assembly after wear or ring damage,
• service work where correct clearances and preload/clamping force are important.

SYMPTOMS - WHEN IT’S WORTH REPLACING

Symptoms suggesting the expansion ring should be replaced:

• visible cracks, deformation, or permanent “flattening”,
• reduced spring force (ring does not return to shape after unloading),
• problems assembling the pump section correctly or maintaining proper part alignment,
• unusual friction/rubbing caused by incorrect spacing or preload,
• recurring issues after repair when a worn ring could not ensure proper system operation.

HOW TO CHOOSE THE RIGHT PART

Select based on technical data - similarly described parts may differ in dimensions and spring characteristics:

• by manufacturer MPN / reference: 40021,
• by dimensions: 25×4×25 and the “20 mm” application designation,
• by comparison with the removed part: check thickness, diameters, and spring condition.
• Accurate fit is important for correct assembly and durability of cooperating pump components.

COMPATIBILITY

Compatibility should be confirmed by MPN 40021 and the 25×4×25 dimensions in the pump documentation/parts table.
Selecting only by the general “20 mm ring” description without verifying the reference and dimensions is not recommended.

[faq]

What is the expansion ring used for in a high-pressure pump?|It is a spring/expanding element that helps maintain correct seating and preload of cooperating parts. It supports correct assembly and stable operation of the pump section.
Can I select the ring only by the 25×4×25 size?|Dimensions are key, but the safest approach is to confirm selection by MPN 40021 and pump documentation. In practice, tolerances and the ring’s spring behavior can also matter.
Can an aftermarket expansion ring be used?|Yes, provided dimensions match exactly and it delivers the correct spring function in the given assembly. Incorrect selection can complicate assembly or affect pump section operation, so the MPN and specification should be your reference point.

[/faq]