FIGURE 55
TOOL CIRCUIT
Tool Circuit
The tool cylinder is located at the end of the telescope boom. It is fastened to the boom at the cylinder base, and to
the bucket adapter at the rod end. The cylinder is protected from bottoming out in either direction by bucket stops
welded to the bucket adapter. Cylinder re-pack kits are available from your GRADALL Distributor.
Tool (Bucket) Control Valve
The bucket valve consists of two port reliefs, a section compensator and compensator regulator.
See Figure 54
Fluid
flows from the front pan when the front end cap is pressurized. When the joystick is actuated, the pilot signal shifts
the valve spool and the compensator meters fluid to the spool. The spool then routes fluid to the bucket cylinder.
The valve load sense system controls compensator shift and signals the pump load sense system.
Bucket-close speed is controlled by valve spool notches. When this circuit is bottomed, the regulator opens and
allows the compensator to shift, cutting off fluid to the bucket circuit until pressure drops below the regulator
setting. Port reliefs protect against external loads. Maximum flow rates out of the A (front) and B (rear) ports are
26 and 30 GPM respectively.
XIV. Tool Circuit
(continued)
48
Tool Cylinder
Tool Open
Tool Close
Tool
C.V.
Pilot Pressure
Tank
L.H.
Joystick
Main Pump
NOTE!
Fluid Path Simplified for Clarity
P - Pilot Pressure
T - Return Fluid To Tank
A/B - Main Control Valve Ports
Form No. 29704
Summary of Contents for XL4000
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