Service Guide for Danfoss PAHT 20-32 and PAHT G 20-32 Pumps

Important Information

This document provides instructions for disassembling and assembling Danfoss PAHT 20-32 and PAHT G 20-32 axial piston pumps. Note: If the pump is disassembled within the warranty period, the warranty is void.

General Requirements:

• The pump must be serviced in conditions of absolute cleanliness.
• Do not use silicone when assembling the pump.
• Do not reuse disassembled O-rings; always use new ones.
• Lubricate all threads with PTFE lubrication type to prevent seizing.
• Lubricate all parts to be assembled with clean filtered water (especially PEEK parts).

Disassembling the Pump

The disassembly process involves removing the mounting flange, shaft sealing, spring, guide pins, O-rings, cover, pistons, retainer plate, cylinder barrel, port plate, and thrust plate. Follow the step-by-step visual guide provided in the manual (pages 3-8) to ensure correct removal of components.

Inspection Criteria

Before reassembly, inspect the following components for wear:

• Valve and Thrust Plate: Must not show signs of wear. Check tightness against a light source using a ruler.
• Swash Plate: Surface must be smooth without scratches deeper than 0.1 mm.
• Pistons: Play in the ball and socket joint must not exceed 0.1 mm. Piston shoe thickness must be at least 4.1 mm. Surfaces must be even and smooth.
• Bearings: Check main bearings and cylinder barrel bushes for wear and scratches.

Assembling the Pump

Assembly is the reverse of disassembly, requiring strict adherence to cleanliness and lubrication protocols. Ensure all guide pins and O-rings are correctly positioned. Specific torque settings are provided in the exploded views on pages 21 and 23.

Spare Parts and Tools

The manual includes detailed spare parts lists for both PAHT 20-32 and PAHT G 20-32 models, identifying specific seal sets, cylinder barrel sets, valve plate sets, and swash plate sets. A dedicated tool set (180Z0236) is required for proper maintenance.