Chapter 7
Maintenance and Repair Notes
DM55 DynaDrum PP V6, Manual No.21-18, Rev.2.19 Page 117
7.3 Piston Pump Oil Cavity
The DM55’s piston pump has been designed with a dry-running pump shaft seal and is
used successfully in both hot melt and PUR systems. However, there is a small oil cavity
above the bearing shaft seal assembly that may be maintained with throat seal lube (PSA
or PUR, see spare parts list) if the customer or the pumping material require further
barrier. Consult ITW Dynatec for compatibility of any other barrier materials prior to use
as it may damage the seal and void the warranty.
No disassembly is required to access the cavity. Operate the piston pump at the minimum
pressure required to reduce wear as increased pressure beyond the needed range rarely
increases performance.
7.4 Piston Pump Inlet Check Valve Cleaning
Charred adhesive or other “trash” in the pump inlet check valve may cause the piston
pump to leak or become plugged with adhesive. In this case, the lower end of pump body
must be exposed, the check valve inspected and cleaned.
Prior to disassembly, heat the unit above the softening point of the material in the pump.
Switch pump motor OFF. Activate the applicator to relieve pressure. Elevate the platen to
make work easier.
Heed all security advices given in chapter 7.1.
Maintenance and repair work is only permitted for skilled personnel!
Always wear safety shoes, heat-resistant protective gloves, safety goggles and
protective clothing that cover all vulnerable parts of the body while working on the
heated unit! Risk of injury or severe burns!
• Disconnect main electrical power.
• Disconnect air pressure at air control panel.
• Provide safety blocking under the platen.
Note: a drum with a lid and fiber separator sheet between the lid and platen may
be used as a safety block to prevent lowering of the platen.
1. Loosen coupler and swing the stainless steel connection shaft up clear of the pump.
Remove coupling from top of connection shaft.
2. Loosen four pump air motor bracket bolts.
3. Loosen four bolts which mount the pump to the platen cover. Raise the pump body up
and out of the platen.
WARNING HOT SURFACE & HOT ADHESIVE
Hot, molten material may flow from the pump.
CAUTION: For high viscosity materials, it may be necessary to heat the
platen to full operating temperature. The high viscosity material may
make the pump difficult to remove.
4. Inspect inside the lower end of the pump body. Clean any char or plugged adhesive
from the inlet check valve area.
5. Reassemble pump to melter in reverse order.
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