Usage:
Hydraulic System
Introduction
NOTE: For Specifications with illustrations, make reference to the HYDRAULIC SPECIFICATIONS for 153 & 163 HYDRAULIC CONTROL, Form No. REG01693. If the Specifications given in Form REG01693 are not the same as in the Systems Operation and the Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications in the book with the latest date.
The operation of the blade lift cylinders, blade tilt cylinders and ripper cylinders are controlled by the Hydraulic Control. The machine may be equipped with all or any part of the arrangement.
COMPONENT LOCATION
1. Control lever for blade lift. 2. Control lever for ripper. 3. Ripper cylinder. 4. Control valve for ripper.
The location of the hydraulic tank is in front of the dash. The filter, one or more control valves, pressure relief valve, load check valve and make-up valve are located inside the tank.
COMPONENT LOCATION
5. Lift cylinders. 6. Hydraulic tank. 7. Tilt cylinder. 8. Control pedals for blade tilt.
When the hydraulic control is installed on a D6 Tractor, the hydraulic pump is mounted on the left front side of the engine flywheel housing and is driven by the drive gear for the hydraulic pump.
When the hydraulic control is installed on a D5 Tractor, the hydraulic pump is mounted on the left rear side of the engine timing gear cover and is driven from the timing gears.
PUMP AND LINES (D6 Tractor)
9. Pump outlet line. 10. Pump inlet line. 11. Pump.
PUMP AND LINES (D5 Tractor)
9. Pump outlet line. 10. Pump inlet line. 11. Pump.
EXTERNAL CONTROL VALVE
In the single valve tank, the control valve has four positions: RAISE, HOLD, LOWER and FLOAT. This valve controls the operation of the lift cylinders.
In the double valve tank, the control valve has two valve spools in one body.
The valve spool with four positions controls the lift cylinders the same as in the single valve tank. The other valve spool is a three position valve. When used to control the tilt cylinder, it controls TILT RIGHT, HOLD and TILT LEFT positions. When used to control the ripper, it controls RAISE, HOLD and LOWER positions.
When the machine has a double valve tank to control the tilt and lift of the bulldozer blade, an external valve is used to control the ripper. This is a three position valve with RAISE, HOLD and LOWER positions.
SCHEMATIC OF SINGLE VALVE SYSTEM (For Lift Cylinder)
1. Pressure relief valve. 2. Control valve for lift cylinders. 3. Filter. 4. Make-up valve, (Anti-Cavitation). 5. Pump. 6. Lift cylinder. 7. Check valve. 8. Lift cylinder.
SCHEMATIC OF DOUBLE VALVE SYSTEM (For Lift Cylinder and Tilt Cylinder)
1. Pressure relief valve. 2. Control valve for tilt cylinder or ripper cylinder. 3. Control valve for lift cylinders. 4. Filter. 5. Make-up valve, (Anti-Cavitation). 6. Ripper cylinder. 7. Tilt cylinder. 8. Pump. 9. Lift cylinder. 10. Check valve. 11. Check valve. 12. Lift cylinder.
SCHEMATIC OF DOUBLE VALVE SYSTEM WITH EXTERNAL VALVE (For Lift Cylinder, Tilt Cylinder and Ripper Cylinder)
1. Ripper cylinder. 2. Pressure relief valve. 3. Control valve for tilt cylinders. 4. Control valve for lift cylinders. 5. Filter. 6. Make-up valve, (Anti-Cavitation). 7. Tilt cylinder. 8. Pump. 9. Lift cylinder. 10. External control valve. 11. Check valve. 12. Check valve. 13. Tilt cylinder.
Operation In Hold Position
The valve spools are held in HOLD position by springs. The oil in the head ends and rod ends of the cylinders is stopped at the control valve.
When the control levers are in HOLD positions, the flow of oil goes through the system as follows:
Oil from the pump goes to the control valve spool or spools. The oil goes past the valve spools to the filter, through the filter elements to the tank. If the elements have a restriction because of dirt or the oil becomes thick because of cold weather, the pressure of the oil opens a bypass valve in the filter and the oil goes direct to tank.
The pressure relief valve prevents the pressure in system from going higher than its pressure setting. When the pressure gets to the setting of the valve, the valve opens and directs some of the oil to the tank.
Operation Of The Single Valve Tank
Blade Lift Circuit
When the lift control lever is moved to the RAISE position, the lift valve spool (6) moves out of the valve body. Oil from the pump in line (3) goes to check valve (2). The check valve will be closed until the pressure of the pump oil is more than the pressure of the oil in the rod ends of the cylinders and the force of the check valve spring. In this way the check valve prevents reverse flow and cylinder movement when the lift valve spool is first moved. The oil opens the check valve and goes to the rod ends of cylinders (5), raising the blade. Oil in the head ends of the cylinders goes through the filter (8) to the tank.
SCHEMATIC OF BLADE LIFT CIRCUIT (HOLD Position)
1. Pressure relief valve. 2. Check valve. 3. Pump outlet line. 4. Make-up valve (anti-cavitation). 5. Blade lift cylinders. 6. Valve spool. 7. Filter outlet. 8. Filter.
When the control lever is moved to the LOWER position, the valve spool moves into the valve body. Oil from the pump goes to the head ends of the cylinders. The oil in the rod ends of the cylinders goes to the tank.
COMPONENT LOCATION (Single Valve Tank)
1. Pressure relief valve. 2. Check valve. 6. Valve spool. 8. Filter. 9. Float lock detents (four).
Movement of the control lever, beyond the LOWER position, moves the valve spool to the FLOAT position. The head ends and rod ends of the cylinders, pressure chambers and return chambers in the valve body are all open to each other. Oil from the pump opens the check valve and oil goes to the head ends or rod ends of the cylinders as needed or, the oil can go to the tank. This makes the pressure of the oil in both ends of the lift cylinders the same. The pistons move in either direction as needed when outside forces move the blade. The valve spool is held in FLOAT position by detents.
Each piston for the blade lift cylinders has two relief valves. The relief valves are held closed by pressure oil. The relief valves open when the piston contacts either end of the cylinder. This will permit the oil on the pressure side of the piston to go through the piston and goes to the tank.
Make-up Valve (Anti-Cavitation Valve)
The make-up valve is on the control valve body. The make-up valve will open and the oil will go from the tank to add to pump flow when the piston rods move out faster than the pump can supply oil to the head ends of the lift cylinders.
Pressure Relief Valve
When the pressure in the system goes to the setting of the relief valve, pilot valve (5) moves back against the force of spring (6). Oil in chamber (4) goes to the tank through the open pilot valve. The pressure in chamber (4) lowers. The pressure in the system moves dump valve (2) into body (3) against the force of spring (1). Pump flow goes to tank through the open dump valve. The setting of set screw (7) controls the force of the pilot valve spring (6) on the pilot valve (5). Changing the setting of the set screw will change the relief valve opening pressure.
PRESSURE RELIEF VALVE
1. Spring. 2. Dump valve. 3. Body. 4. Chamber. 5. Pilot valve. 6. Spring. 7. Set screw.
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Do not turn the set screw (7) all the way in because this will not let the pilot valve move. This will result in high oil pressure in the hydraulic system and cause damage to its components or injury to personnel. |
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Operation Of The Double Valve Tank And Double Valve Tank With External Control Valve
The two and three valve systems have a "modified series circuit." In these systems, return oil from the cylinders (blade tilt or ripper) that is controlled by the first valve in the tank, goes to tank in a two valve system or to the external valve in a three valve system. Oil from the pump can not go to the blade lift control valve, (second valve in tank) when the first valve is in an operating position.
Blade Lift Circuit
The operation of the blade lift circuit is the same as that given in the SINGLE VALVE TANK.
SCHEMATIC OF THREE VALVE HYDRAULIC SYSTEM (HOLD Position)
1. Pressure relief valve. 2. Check valve for the tilt circuit. 3. Tilt cylinder. 4. Pump outlet line. 5. Valve spool for tilt circuit. 6. Check valve for the lift circuit. 7. Make-up valve (anti-cavitation) for head end of the lift cylinders. 8. Lift cylinders. 9. Valve spool for the lift circuit. 10. Check valve for the ripper circuit. 11. Valve spool for the ripper circuit. 12. Filter. 13. Filter outlet. 14. Ripper cylinder.
COMPONENT LOCATION (Two Valve Tank)
1. Pressure relief valve. 2. Check valve for the tilt circuit. 5. Valve spool for the tilt circuit. 6. Check valve for the lift circuit. 9. Valve spool for the lift circuit. 12. Filter. 15. Float lock detents (four).
EXTERNAL CONTROL VALVE FOR THE RIPPER
10. Check valve for the ripper circuit. 11. Valve spool for the ripper circuit.
Blade Tilt Circuit
The blade tilt circuit is controlled by two pedals. Pushing the left pedal lowers the left side of the blade (TILT LEFT). Pushing the right pedal lowers the right side of the blade (TILT RIGHT).
When the right pedal is pushed, the valve spool (5) is moved out of the valve body. Oil goes to the check valve (2). The check valve will be closed until the pressure of the pump oil is more than the pressure of the oil in the head end of the tilt cylinder and the force of the check valve spring. In this way the check valve prevents reverse flow and cylinder movement when the tilt valve spool is first moved. The oil opens the check valve and goes to the head end of the cylinder (3), tilting the blade to the right (lowers right end of blade). Oil in the rod end of the cylinder goes through the oil filters (12) to the tank.
When the left pedal is pushed, the valve spool is moved into the valve body. Oil from the pump goes to the rod end of the cylinder, tilting the blade to the left (lowers left end of blade). Oil in the head end of the cylinder goes through the control valve to the tank.
Ripper Circuit
The ripper is controlled either by an external valve on a three valve system or a valve in the tank on a two valve system.
Ripper Control Valve (In Tank)
The control valve is the same as that used to control the tilt circuit in a three valve system.
When the ripper control lever is moved to the RAISE position, the ripper valve spool is moved out of the control valve body. Oil from the pump goes to the ripper circuit check valve. The check valve opens and the oil from the pump goes to the rod end of the ripper cylinder, raising the ripper. The oil in head end of the cylinder goes through the filter to the tank.
When the control lever is moved to the LOWER position, the valve spool is moved into the valve body. Oil from the pump goes to the head end of the cylinder. The oil in the rod end goes through the filter to the tank.
Ripper Control Valve (External)
When the ripper control lever is moved to the RAISE position, the valve spool (11) is moved into the control valve body. Oil from the pump opens the check valve (10) and goes to the rod end of the cylinder (14). The oil in the head end of the cylinder goes through the filter (12) to the tank. In LOWER position the oil from the pump goes to the rod end of the cylinder.
RIPPER CONTROL VALVE (EXTERNAL)