TM 5-3805-261-20
PRINCIPLES OF OPERATION. (cont)
1-30.
GAGES AND INDICATORS (NON-ELECTRICAL). (cont)
j.
Fuel Level Dipstick (Figure 1-64). Located in fuel fill opening. Calibrations show FULL, EMPTY, and
percentage of fuel in tank.
Figure 1-64.
1-31.
BLADE SYSTEM. The blade system uses hydraulic cylinders and a hydraulic circle drive motor to move the blade.
The hydraulic system provides power for the cylinders and motor. Refer to paragraph 1-29 for hydraulic system operation
and location of components. The blade control levers are located at the sides of the steering console in the cab. Refer to
paragraph 1-29 for description of control valve and lock deck valve. Refer to TM 5-3805-261-10 for blade operating
instructions and exact location of operator’s controls. The blade centershift lock is powered by pressurized air. Refer to
Appendix F, Section II, paragraph F-5.
When the engine is running, the oil from the variable displacement pump goes through the relief and pressure reduction
valves, through lines to the control valves for the blade system cylinders. The pressure of the oil can get as high as the
pressure setting of the relief valve. When the control valves for the blade system cylinders are not being used, the
pressure of the oil is 2150 psi.
When the engine is running and the cylinders are not being used, the pressure of the pump oil to the control valve is
approximately 2150 psi. 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. Lock check valve stops the oil in the lines between pressure reduction valve and cylinder and
the rod in the cylinder cannot move.
When the blade control valve lever for the cylinder is held in the forward position, the pump oil goes through control valve
through lines and lock check valve into the head end of cylinder. The oil in the head of cylinder pushes the piston and rod
out of the cylinder which moves the blade. When more force is needed, 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 1500 psi, the oil moves the shuttle valve in the
pump and the oil pressure from the pump can go to approximately 3500 psi.
1-52
