Alamo MACHETE Product Service Manual page 28

CONTROL VALVE - HYDRAULIC
CONTROL VALVE COMPONENTS: Load Sensing Valve End Cap
The Control Valve for Both Type Systems (Load Sense or Fixed Displacement) consists of the
same basic components. The Difference between the Control Valves for the two systems involves the
components in the Inlet Section. The Inlet Section (End Cap) of the Load Sensing (Closed Center) Valve
(Figure 12) contains the following components.
1. Pressure Bypass Adjustment Spool
3. Pressure Relief Valve
5. Load Sense Orifice
Tank Port ("T")
Load Sense Signal
The Load Sensing Valve (Closed Center) Version, An Orifice with an Outer Plug are used in
place of the Plug which was used in the Fixed Displacement (Open Center) Version. Therefore the
Pressure Adjustment Spool will only open to Tank when the Pressure in the Pressure Port "P" exceeds
the value of the Pressure relief.
The Load Sense Signal or Load Pressure is led to the Tractor Pump Regulator via the Load
Sense Connection.
In the Neutral Position the Pump Control sets the Displacement so that leakage in the system
is compensated for and the Standby (Pilot) Pressure is maintained (approx. 200 to 250 PSI).
When a Main Spool is activated, The Pump Regulator will adjust the displacement so that
the set differential pressure between the Pressure Port "P" and the Load Sense Signal pressure is
maintained.
MACHETE (Service Manual) 04/04
© 2004 Alamo Group Inc.
LOAD SENSING VALVE END CAP
Pressure Relief
Plug
2. Pilot Reducing Valve
4. Load Sense Passage Outer Plug
Pilot Reducing Valve
Pressure Port ("P")
Pressure Gauge Port
Orfice
FIGURE 12
Pressure Bypass Adjustment Spool
28