Danfoss 51 Series Service Manual

Also see for 51 Series: Service Kit Instructions Service manual Repair instructions Service manual Service manual

Danfoss 51 Series Service Manual Manual pdf 19 page image

Pressure-compensator controlsPressure compensator (PC) controls allow the motor to match its displacement to the system load.Usually this means that the motor defaults to minimum displacement while allowing the motor toincrease displacement when system pressure reaches a set level due to load. This permits the motor toregulate system pressure by modulating the displacement angle of the rotating group. As displacementincreases, so does available torque, while output speed decreases and system pressure remains nearlyconstant at the PC setting.PC controls are available with a Brake Pressure Defeat (BPD) feature. The BPD feature defeats theoperation of the PC during dynamic breaking (when the motor is running as a pump).A shuttle spool upstream of the PC valve directs only acceleration system pressure to the PC. Duringdynamic deceleration the dynamic breaking pressure is blocked from the PC. The motor remains atminimum displacement, limiting rapid and uncontrolled pressures or engine over-speeding while thevehicle/machine is slowing down. Hydraulic or electric actuation is available. PC on one system-pressureside is also an option.Complete functional description, maintenance, and repair procedures for pressure-compensator controlsare covered in detail in the supplement to this manual:• 11009442 Series 51 Two Position Controls Service ManualTypes: T1, T2, TH, TA, PC, PDService ManualSeries 51 and 51-1 MotorsOperation© Danfoss | March 2016 11008567 | AX00000013en-US0202 | 19