Manual Displacement Control (Mdc); Mdc Torque - Danfoss H1 Series Technical Information

Technical Information
H1P 115/130 Axial Piston Single Pumps
Control Options

Manual Displacement Control (MDC)

20 | © Danfoss | May 2018
A Manual proportional Displacement Control (MDC) consists of a handle on top of a rotary input shaft.
The shaft provides an eccentric connection to a feedback link. This link is connected on its one end with a
porting spool. On its other end the link is connected the pumps swash-plate.
This design provides a travel feedback without spring. When turning the shaft the spool moves thus
providing hydraulic pressure to either side of a double acting servo piston of the pump.
Differential pressure across the servo piston rotates the swash plate, changing the pump's displacement.
Simultaneously the swash-plate movement is fed back to the control spool providing proportionality
between shaft rotation on the control and swash-plate rotation.
The MDC changes the pump displacement between no flow and full flow into opposite directions. Under
some circumstances, such as contamination, the control spool could stick and cause the pump to stay at
some displacement.
A serviceable 125 μm screen is located in the supply line immediately before the control porting spool.
The MDC is sealed by means of a static O-ring between the actuation system and the control block. Its
shaft is sealed by means of a special O-ring which is applied for low friction. The special O-ring is
protected from dust, water and aggressive liquids or gases by means of a special lip seal.
Manual Displacement Control
P301 749

MDC Torque

Description
Torque required to move handle to maximum displacement
Torque required to hold handle at given displacement
Maximum allowable input torque
C
Caution
Volumetric efficiencies of the system will have impacts on the start and end input commands.
Pump displacement vs. control lever rotation
100 %
-d -b -a
Lever rotation
"A"
"0"
a
-c
100 %
Legend:
Deadband on B side – a = 3° ±1°
Maximum pump stroke – b = 30° +2/-1°
Required customer end stop – c = 36° ±3°
Internal end stop – d = 40°
Value
1.4 N•m [12.39 lbf•in ]
0.6 N•m [5.31 lbf•in]
20 N•m [177 lbf•in]
d
"B"
b c
P301 752
BC00000198en-US0901