The orifice (K) restricts the incoming charge supply to
To put the pump in stroke, the control handle (A) moves
limit the maximum servo response rate. Spring (C)
the displacement control spool (B) through a spring (C).
allows the operator to rapidly preselect the desired
The spool ports oil under charge pressure (D) to a servo
speed setting without waiting for the swashplate to
cylinder (E). The piston moves the swashplate (F)
follow-up.
against the opposite servo spring (G). Both servo
When the mixer control handle is moved to neutral
springs are constrained so that they can only force the
position, the displacement control spool is returned to
swashplate toward neutral. When the swashplate has
neutral by a spring (J). This allows oil from both servo
moved to the angle set by the control handle, the feed-
cylinders to flow into the pump case through the small
back link (H) returns the displacement control spool
underlaps (I). (Refer to figure 4.) Both servo cylinders
almost to neutral where it ports just enough oil to the
are thus exhausted and one of the servo springs (G)
servo cylinder to keep the swashplate at the proper
mechanically forces the swashplate to neutral.
angle.
FIGURE 3
FIGURE 4
43
