FIGURE 58
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 59
Fluid flows from the front port 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)
Tool Cylinder
Tool Open
Tool Close
Tool
C.V
Main Pump
L.H.
Joystick
Pilot Pressure
Tank
Form No. 29703
50
P - Pilot Pressure
T - Return Fluid To Tank
A/B - Main Control Valve Ports
Fluid Path Simplified for Clarity
NOTE!
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