Parker Hydraulic Group
NDS20 Series Pressure-Summation Unloading Gear Pumps

Key Features

  • Flows to 98 GPM per section
  • Tandem & triple section units available
  • Pressures to 2500 PSI
  • Speeds to 2500 RPM
  • Pressure & flow sensing valves available
  • Dry valve option
  • Piggy back option available
  • Also available as motor
  • Cast iron versions available
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Tandem Pump with Pressure-Summation Unloading Valve

The NDS pump system is essentially the same as the NSH system, except the unloading pressure signal is the summation of the internal pressure, plus an external pressure from another pumping system. The NDS system is useful in limiting the horsepower withdrawn from the prime mover in a multiple pump circuit system.

If System B is operating at minimum pressure, then the NDS circuit (System A) can operate at a high pressure-high flow before unloading the rear pumping section.

If System B is operating at high pressure, then the NDS circuit (System A) would unload the rear pumping section at a lower pressure to avoid overloading the engine. This relationship can be seen in the chart which illustrates the unloading characteristics for the NDS system, when used in conjunction with another hydraulic pump (syetem B).

Description ........... Pressure-Summation Unloading Gear Pumps
Combined Flow Range ...... To 98 GPM Per Section (370.9 LTR.)
Displacements .... To 9.10 C.I.R. Each Section(149.12 CC’s/REV.)
Maximum Pressure to ...................................... 2500 PSI (172 BAR)
Maximum Speed to ........................................................... 2500 RPM
Rotation ......................................................................................A or C
Bearings ................................................................................... Journal
Construction .......................................................................Aluminum