Alamo MACHETE Product Service Manual page 88

MOTOR - ELECTRICAL CONTROL
Note:
The Servo Control Valve, Lever and Solenoid have been replaced a manifold and
Solenoid valve Cartridge, Please make note on all diagrams and text.
The Method used on the Machete to transmit Engine Power to the Mowing Head is called
a "Closed Loop" or " Hydrostatic" System (Figure 39). Engine Power is converted to Hydraulic
Power by the Variable Displacement Hydraulic Piston Pump. Oil is sent to the Fixed Displace-
ment Motor through the Hoses that run down the Boom. Oil passing through the Motor converts
the Hydraulic Power Back into Mechanical Power to Rotate the Blades.
The Shuttle Valve in the Motor returns 8 GPM back to the Tank for Cooling. The remain-
der of the return oil remains in the Closed Loop. Some of the advantages of using a Closed
Loop System for the Motor Circuit are 1. A Smaller quantity of Oil is required, 2. System acts as
its own "Brake" slowing down the Blades and 3. Less Fuel consumed due to "No Load" condi-
tion when Motor Circuit is disengaged.
Another feature of the Alamo System is that the Oil is filtered after it leaves the Charge
Pump and before it enters the High Pressure Loop.
Solenoid Activation
Wires (2 Wire)
Manifold
Servo
Servo
Piston
CCW
SERVO CONTROLLED
PISTON MOTOR
The Motor Circuit is engaged by two Manually Operated Switches (See Figures 36, 37, & 38
for Types Used). These Switches have varied from "On - Off" to "Momentary', But all have served the
same purpose. Closing the Switches completes a Circuit through the Solenoid. The Purpose is for
a "Solenoid" to actuate a Pump Control, which actuates a Valve to turn on Pump; this has varied some
over the years. This movement causes the Camplate in the Pump to move. Movement of the
Camplate when the Pump is turning causes the length of Piston Stroke to Change, Causing Oil to too
be moved. The Greater the Angle, the longer the stroke, The longer the stroke the more Oil is Pumped,
and the more oil pumped means faster the motor turns.
Machete (Service Manual) 04/04
© 2004 Alamo Group Inc.
Control Relief
Line To Filter
Valve
Case
Drain
Charge
Pump
Suction
Return From Filter
Port "C"
Charge
Pump R/V
Port "A"
88
FIGURE 39
MOTOR
From Shuttle
Valve to Tank