IMPLEMENT HYDRAULIC SYSTEM CONTINUED
6. Lowering Implement with a Dead Engine
The implement circuit is still operable when the engine is dead. However, the key must be in the ON position in
order to make it operate.
The accumulator stores potential energy while the engine is running by accumulating a quantity of pressurized
hydraulic oil. When the engine is dead, the accumulator supplies oil to the pilot valve.
As the operator moves the joystick, oil flows from the accumulator to the end of the lift spool valve. The lift spool
valve shifts and the trapped oil in the lift cylinders flows back to the hydraulic tank as gravity lowers the attachment
to the ground.
When the front of the machine is off the ground, there is pressure on the rod end of the lift cylinders. Oil from the
accumulator is now used as pilot oil in order to shift the lift valve spool to the LOWER position. The oil that was
trapped in the rod end of the lift cylinders flows back to the hydraulic tank as the machine lowers.
7. Lowering Implement with a Dead Accumulator and Dead Engine or Dead Electronics
Oil pressure stored in the accumulator is not usable for lowering the lift cylinders if the accumulator and the engine
are dead or if the electronics are dead. In this case, you must turn dead engine LOWER screw (Figure 12, Item 1)
in order to get the oil to flow from the lift cylinder back to the tank.
Figure 12. Blade Raise Control Valve.