Control Response; Mdc Response Time; Neutral Start Switch (Nss) - Danfoss H1 Series Technical Information

Technical Information
H1P 115/130 Axial Piston Single Pumps
Control Options
22 | © Danfoss | May 2018

Control Response

H1 controls are available with optional control passage orifices to assist in matching the rate of swash-
plate response to the application requirements. The time required for the pump output flow to change
from zero to full flow (acceleration) or full flow to zero (deceleration) is a net function of spool porting,
orifices, and charge pressure.
H1 pumps are limited in mechanical orifice combinations. Mechanical servo orifices are to be used only
for fail-safe return to neutral in a case of an electrical failure.
A swash-plate response times table is available for each frame size. Testing should be conducted to verify
the proper orifice selection for the desired response. Typical response times at the following conditions:
∆p = 250 bar [3626 psi]
Charge pressure = 20 bar [290 psi]
Viscosity and temperature = 30 mm²/s [141 SUS] and 50 °C [122 °F]
-1
Speed = 1800 min (rpm)

MDC Response Time

Code Orifice description (mm)
P A
– –
C3
– –
C6
– –
C7
1 –
D1
1.3 –
D2
1.3 –
D3
1.3 1.3
D4
1.3 –
D6

Neutral Start Switch (NSS)

The Neutral Start Switch (NSS) contains an electrical switch that provides a signal of whether the control
is in neutral. The signal in neutral is Normally Closed (NC).
Neutral Start Switch schematic
M14
M5
B Tank (A+B) Neutral to full flow
– – 0.6
– 1 2.2
– 1.3 1.4
– 0.8 3.9
– 0.8 3.5
– 1 2.5
1.3 1 3.0
– 1.3 1.9
M4 M3
P005 702
Stroking direction (sec)
Full flow to neutral
0.7
1.9
1.3
3.1
2.8
2.0
2.4
1.5
BC00000198en-US0901