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Improper use of the boom and work tools could result in injury or death. The operator must be fully aware of all the functions for the joystick control and proper operating techniques. |
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| Illustration 1 | g00671544 |
Illustration 1 shows the current model of joystick. The joystick on the left side of the page is in the centered position. The joystick on the right side of the page is in the raise position. (1) Lever (2) Switch (push button) (3) Switch (push button) (4) Switch (push button) (5) Tank (gallery) (6) Dust cover (7) Swivel joint (8) Plunger (9) Spool (10) Spring (11) Centering spring (12) Hole (13) Supply (gallery) (14) Pilot port (boom retract) (15) Pilot port (boom raise) (16) Boom retract or tilt back for quick coupler (17) Supply port (18) Pilot port (boom lower) (19) Tank port (20) Return to tank (21) Pilot pressure (22) Reduced pressure from bank valve | |
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| Illustration 2 | g00841544 |
Early arrangement | |
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| Illustration 3 | g00841545 |
Current arrangement | |
There are two types of operating arrangements for the Joystick. For information on the early arrangement of the joystick, Refer to the Operation and Maintenance Manual, SEBU7017. For information on the current arrangement of the joystick, Refer to the Operation and Maintenance Manual, SEBU7111.
The joystick is located at the right side of the operator compartment. Early joystick handles are straight. The early joystick handles have a push button switch on the front side of the handle and the handle has a rocker switch on the top side. Current handles are curved. The current handles have push button switches on the front, on the rear and on the top of the handle. The hydraulic valve section of the early joystick is the same design as the current joystick.
The oil supply to the joystick is from a pressure reducing valve that is located in the end section of the directional control valve. The pressure is set to 2490 kPa (360 psi).
In order to operate one valve at a time, the joystick can be moved in the following directions: forward, rearward, left and right. The joystick can be moved in a diagonal direction in order to operate two valves at the same time. The speed of the function that is controlled by the joystick is directly proportional to the amount of the movement of the lever.
There are four valves in the hydraulic valve section of the joystick. Each of the valves consists of the following components: plunger (8), spool (9) and control spring (10). The joystick is centered by springs (11). The springs (11) hold plungers (8) against swivel joint (7). The reducing valves are connected to a common supply gallery (13). The reducing valves are connected to a common tank gallery (5). The outlet from each of the reducing valves is connected to a pilot port on the bank valve.
When the lever is centered, the oil flow from the supply is blocked by the plungers of the reducing valves. The pilot ports are connected to the tank gallery through the center of the plungers and holes (12). The holes ensure that the directional control valve spools are centered.
When the joystick is moved, the swivel joint is tilted and the swivel joint presses one of the plungers in a downward direction. The plunger is pressed against centering spring (11). As the plunger is moved in a downward direction, spool (9) is moved downward through centering spring (11) .
When holes (12) in the spool are closed off from the tank gallery, the holes begin to align with the supply gallery. Oil flows from the supply gallery through the holes and the center of the plunger and from the pilot port to the selected section of the directional control valve.
The pressure of the pilot oil is determined by the amount of movement of the joystick. The amount of offset of the spool of the directional control valve is determined by the movement of the joystick. When the pressure of the pilot oil rises slightly above the force of control spring (10), the plunger will move until the pilot pressure and the force of the control spring are equalized. The holes in the plunger are now covered. The reducing valve is now balanced and the pilot pressure will not rise.
Further movement of the joystick will move the plunger downward. This will uncover the holes and the pilot pressure will begin to rise. The spool of the directional valve will be offset until the force of the control spring is equalized by the pilot pressure. The plunger moves up until the holes are covered.
The plunger will remain in the down position and the pilot pressure will be at the maximum pressure when the movement of the joystick is at the maximum. The spool of the directional control valve will be fully offset. The range of the pilot pressures is799 kPa (116 psi) to 2398 kPa (348 psi).