Alamo MACHETE Product Service Manual page 66

PUMP CIRCUIT - MOTOR DIS-ENGAGE
Motor Circuit Disengage (w/ Engine Running)
The Alamo Closed Loop Motor Circuit ic considered to be Neutral when there is no output
being generated by the Variable Displacement Pump, as the Shaft, Internal components and Charge
Pump are being driven by Tractor Engine. The Canplate is in the centered position and the length
of Stroke of the Pistons is equal, therefore there is no flow being generated by the pump
At this point the Charge Pump is drawing Oil through a Suction Screen from the Tank to
provide flow to perform the following functions.
1. Keep the Circuit Primed and make up internal leakage.
2. Maintain Back Pressure on Pump asnd Motor Pistons
3. Operate Control Funtions to Start Pump.
4. Maintain Temperature Control, to prevent Oil Heating in Pump.
Oil from the Charge Pump is directed to two dual pupose system Relief and Check Valves
(Figure 41). Since the Charge Pressure is greater than the pressure in either side of the Closed Loop
, The Check Valves open and charged Oil (at Charge Pressure) is available to both sides of the
closed Loop. When the System is primed, any excess Oil is relieved through the Charge Pump relief
Valve, which maintains a pressure of 250 to 300 PSI.
The Piston Pump remains in Neutral as long as the Camplate remains in the centered
position, this is controlled by the Servo Control System, If Pump does not stay in neutral check the
Neutral Adjusting screw. This is usually noticed by Motor wanting to run.
Neutral
Centering
Spring
Solenoid
Servo
Control
Servo Piston
Machete (Service Manual) 04/04
© 2004 Alamo Group Inc.
Port "D"
To Motor
Camplate
Piston Asy.
Case Drain
Neutral Adjustment
Servo Control Supply Oil
System Relief &
Check Valve
FIGURE 41 PUMP
66
Port "C"
From Motor
Gerotor
Charge
Pump
Charge
Pump
Suction
Charge
Pump
Relief
Valve
System Relief
& Check Valve