Piston & Spring Assemblies

Portable Pressure Washer Familiarization and Troubleshooting Guide Section 7 • Large Frame Pump

Inspect the jam nut and the Belleville washer for wear or damage. Replace if necessary. Units with Straight Engine Shaft: Referring to Figure 7.24, carefully inspect the engine adapter bearing and the axial cam bearing assemblies for wear, damage, freedom of rotation, or evidence of overheating. Replace any damaged or defective bearing assembly.

Figure 7.24 - Axial Cam Drive Components (Units with Straight Engine Shaft) Piston & Spring Assemblies Referring to Figure 7.9 (seen earlier), inspect the three (3) pistons carefully. Replace all three pistons and piston shoes as a set if any one piston is scratched, dented, chipped, or otherwise damaged.

CAUTION: Do not strike a piston with any object or use a piston to strike any object. Do not drop the piston. Dropping the piston will result in damage. Measure the piston diameter and the piston length (as shown in Figure 7.25). If the values are not within the tolerances specified below, replace all three pistons as a set:

Figure 7.25 — Piston Dimensions

Item Name 1 Engine adapter 2 Roller thrust bearing assembly 3 C-ring cam retainer 4 Washer retainer 5 Thrust washer 6 Engine shaft adapter 7 Axial cam 8 Piston pivot bearing assembly

Check the engine shaft adapter assembly (items 3, 4, 5, and 6), which is a part of the axial cam. Since these parts require factory assembly, they must be replaced as a set. The adapter has a built-in key which mates with an engine shaft keyway. Replace if worn or damaged. Piston diameter: 14.977 mm to 14.985 mm

Piston length: 86.65 mm to 90.05 mm Inspect the piston pivot shoes, depicted in Figure 7.26. Replace pistons and shoes as a set, if damaged.

Figure 7.26 — Piston Pivot Shoe