Alamo MACHETE Product Service Manual page 89

MOTOR - PUMP ACTIONS
Note:
The Servo Control System, (Changed see "Note" on Previous Page)
Pump Output is started by movement of the Variable Displacement Pump Control Lever
(Figure 40). As the Lever is rotated, it moves the Spring centered Servo Control Spool first. Movement
of the Spool allows Charge Pump Oil past the Spool to one side of the Servo Piston (Figure 40). The
Pressurized Servo Piston pushed against the
Camplate (figure 40) causing the Camplate to rotate to a Pre-Set Angle. Oil from the opposite end
of the Servo Piston is exhausted to the Pump Housing through the Control Valve Spool.
When the Control Lever (Solenoid & Block on Current Models) is returned to the Neutral
position, The Spool centers itself, allowing the Pressure on both ends of the Servo Piston to equalize.
The Piston and. Camplate return to a Neutral position and Oil flow from the Piston Pump ceases.
Speed of the Camplate movement is controlled by orifices between the Control Valve and
the Servo Piston.
Neutral Adjustment Screw is to set Servo in Neutral position to prevent flow to motor, a Buzz Bar Head
will have a screw on both sides. Rotary head shown below.
FIGURE 40
PUMP
Servo Piston
Servo Piston Follower
Neutral
Centering
Spring
Servo
Control
Solenoid
Spool
Servo
Pressure
Line
Servo Piston
Machete (Service Manual) 04/04
© 2004 Alamo Group Inc.
Camplate
Camplate
Piston Asy.
Case Drain
Neutral Adjust Screw
Servo Control Supply Oil
Feed Back
Line
System Relief
and Check
Valve
Port "D"
To Motor
System Relief &
Check Valve
89
Control Lever
(removed
on later Model, replaced by
Block with Solenoid)
Port "C"
From Motor
Gerotor
Charge
Pump
Charge
Pump
Suction
Charge Pump
Relief Valve