Adjust the Neutral Start Switch to meet the following three requirements:
1. The distance you can move the control handle without opening the NSS is the
NSS deadband
. The
distance you can move the control handle without moving the control spool enough to port
hydraulic fluid to the pump displacement control cylinders is the
control deadband
. These deadbands
must be concentric.
Since you cannot adjust the position of the control deadband, you must adjust the position of the
NSS deadband to match it.
2. The NSS deadband must be wide enough so the NSS will not open within the loose area of control
handle movement caused by normal operating clearances in the control linkage (control shaft free-
play).
By setting the NSS to open outside this area, the control spool springs or control shaft centering
spring can always return the handle to neutral and re-close the NSS.
3. The NSS deadband must be narrow enough so the NSS will open before the unit builds 7 bar [100 psi]
differential system pressure in either direction.
Neutral start switch adjustment requirements
Control shaft
(free-play)
Control shaft
Total control
shaft rotation
Control deadband
(neutral)
NSS deadband
(switch closed, ON)
P104 147E
Neutral start switch eccentric plug adjustment (condition i)
Center the NSS deadband and the control deadband in relation to each other. Since you cannot adjust
the position of the control deadband, you must adjust the position of the NSS deadband to match it. The
switch pin is located in an eccentric plug which you turn to move the center of the NSS deadband. Ensure
the MDC is installed on the pump and in its neutral position when adjusting the neutral start switch
eccentric plug. The accompanying drawing provides dimensions for an eccentric plug adjustment tool.
Service Manual
Series T90 Axial Piston Pumps
Adjustments
©
Danfoss | March 2020
AX216086485386en-000101 | 37