DMD/DM640 Series Dump Pump For Medium & Heavy Duty Dump Trucks, 6.40 cu in/rev, Mount, 3-Line Operation, 2000.00 PSI Relief Setting

With 3-line operation, a third line runs from the pump's return port back to the tank. That return path lets oil that's displaced during cylinder retraction, or just recirculating while the valve is in neutral, flow back to tank instead of building heat inside the system. A metal sleeve gets installed in the valve inlet port to redirect that flow. It doesn't eliminate heat entirely, but it buys you more time. You can run the pump engaged with the spool in neutral for up to 10 minutes with a 3-line circuit before heat becomes a real concern. With a 2-line setup that number drops to 5 minutes, and the oil temp climbs about 7.5 degrees per minute while you're sitting in neutral. The 3-line circuit is the right call for medium and heavy duty dump work where idle time between raises is common.

This Permco DMD/DM640 series pump is designed as a direct replacement for the Commercial C102D251. Just make sure your mounting and port sizes match up.

Porting is set up for a true 3-line circuit. The inlet (suction) is 1-1/4 NPT, and both the pressure port and the return port are 3/4 NPT.