THEORY OF OPERATION - CONTINUED
Refer to Hydraulic System in this work package for hydraulic system operation and location of hydrau-
lic system components related to scarifier assembly operation.
Refer to TM 5-3805-261-10 for scarifier operating instructions and location of scarifier controls.
The scarifier assembly uses a hydraulic cylinder to move the scarifier upward or downward. The scarifier control lever
is located in the lever group at the right side of the steering console in the cab.
When the engine is running, oil from the variable displacement pump goes through the relief and pressure reduction
valves through lines, to the control valve for the scarifier cylinder. The pressure of the oil in lines can get as high as the
pressure setting of the relief valve. When the control valve for the scarifier cylinder is not being used, the pressure of the
oil in lines is 2,150 psi (14,824 kPa).
When the engine is running, and the scarifier is not being used, the pressure of the pump oil in lines to the control valve
is approximately 2,150 psi (14,824 kPa). The oil in lines and passage is open to the tank and the pressure of the oil in
these lines is the same as the oil in the tank. The lock check valve stops the oil in the lines between the pressure reduc-
tion valve and the cylinder and the rod in the cylinder cannot move. The pressure of the oil in lines is the same as the oil
in the tank.
When the scarifier control valve lever is held in the LOWER position, the pump oil goes through the control valve
through lines and the lock check valve into the head end of cylinder. The oil in the head of the cylinder pushes the piston
and rod out of the cylinder which moves the scarifier down. When more force is needed to lower the scarifier, there is an
increase in the pressure of the pump oil to the head end of cylinder. When the pressure of the pump oil goes to 1,500 psi
(10,342 kPa), the oil moves the shuttle valve in the pump and the oil pressure from the pump can go to approximately
3,500 psi (24,132 kPa).
END OF WORK PACKAGE