 |
|
Hot hydraulic oil under high pressure can remain in the components of the hydraulic system or the power train system after the engine has been stopped. The uncontrolled release of the hydraulic oil can cause sudden machine movement and can also result in the following conditions:
If hydraulic oil penetrates body tissue, the injury must be treated immediately by a doctor who is familiar with this type of injury. Use a board or a piece of cardboard to check for a hydraulic oil leak. Make sure that all of the attachments have been lowered to the ground and that all trapped pressure has been released from the hydraulic system and the power train system. Also, make sure that the hydraulic oil is cool before the removal of any components or lines. Remove the hydraulic oil filler cap only when the engine is stopped and the filler cap is cool enough to touch with your bare hand. |
|
|
Personal injury or death can result from not engaging the parking brake. Transmission engagement alone will not prevent machine from rolling when the engine is stopped. |
| NOTICE |
|---|
|
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat® products. Dispose of all fluids according to local regulations and mandates. |
| D6T Implement Pump Pressure | |||
|---|---|---|---|
| Date | Equipment ID Code | ||
| Pump Pressure | Standard(1) | VPAT Blade(2) | Actual |
| Low-Pressure Standby (High Idle) at pressure port (HA) | Maximum |
Maximum |
|
| High-Pressure Cutoff (High Idle) at pressure port (HA) | |
|
|
| Margin Pressure at High Idle | |
|
|
| (1) | Machines that are equipped with bulldozer lift and bulldozer tilt or machines that are equipped with bulldozer lift, bulldozer tilt, and a ripper |
| (2) | Machines that are equipped with a VPAT blade |
| |
| Illustration 1 | g02448491 |
| D6T Torque Specifications | |
| Callout | Torque |
| Locknut (2)
High-Pressure cutoff |
|
| Locknut (4)
Margin Pressure |
|
This story includes the following tests:
- Low-Pressure Standby
- Load Sensing Signal Pressure
- Pump Discharge Pressure
- Margin Pressure
- High-Pressure Cutoff
This story includes the following adjustment procedures:
- Adjustment Procedure - High-Pressure Cutoff
- Adjustment Procedure - Margin Pressure
Note: You can view the discharge pressure of the implement pump through Advisor.
| |
| Illustration 2 | g02571852 |
|
Tooling (A) | |
| |
| Illustration 3 | g01879273 |
|
Tooling (D) | |
| Tool | Item | Part Number | Description | Qty |
|---|---|---|---|---|
| A | 198-4240 | Digital Pressure Indicator Gp | ||
| A1 | 198-4234 | Digital Pressure Indicator | 1 | |
| A2 | 198-4237 | Pressure Sensor (0 to 500 psi) | 1 | |
| A2 | 198-4239 | Pressure Sensor (0 to 6000 psi) | 1 | |
| A3 | 198-4236 | Adapter Cable As | 1 | |
| D | 1U-5796 | Pressure Differential Tool Gp | ||
| D1 | 177-7861 | Hose As | 2 | |
| D2 | 6V-4143 | Quick Connect Coupler | 4 | |
| D3 | 6V-3965 | Fitting | 3 | |
| D4 | 6V-4144 | Quick Connect Coupler | 1 | |
| D5 | 8T-0859 | Pressure Gauge
(0 to 25,000 kPa (0 to 3,600 psi)) |
1 | |
| D5 | 8T-0861 | Pressure Gauge
(0 to 60,000 kPa (0 to 8,700 psi)) |
1 | |
| D6 | 8C-8431 | Tee | 1 | |
| D7 | 1U-5793 | Oil Filter Pressure Differential Gauge Gp | 1 | |
| D8 | 6V-0484 | O-Ring Adapter | 1 | |
Reference: Refer to Tool Operating Manual, NEHS0818, "Using the 198-4240 Digital Pressure Indicator Group" for more information on using Tooling (A).
Reference: Refer to Special Instruction, SEHS8979, "Component Identification and Calibration of the 1U5796 Differential Pressure Gauge Group" for more information on using Tooling (D).
Test Preparation - Low-Pressure Standby
- Move the machine to a smooth horizontal location.
- Lower all the implements.
- Shut off the engine.
- Turn the key to the ON position. Make sure that the implement lockout switch is turned to the UNLOCKED position. Move the implement control levers to all positions several times to release any pressure in the hydraulic system.
Show/hide table
Illustration 4 g03665626 - Pressure port (HA) is located behind the access door on the right fender of the operators station.
- Attach tooling (A) to pressure port (HA). Pressure port (HA) measures the pump discharge pressure.
Test Procedure - Low-Pressure Standby
- Perform the steps in the "Test Preparation - Low-Pressure Standby" and then continue to the following steps.
- Start the engine. Warm the hydraulic oil to a minimum temperature of
65° C (150° F) . - Operate the engine at HIGH IDLE. Make sure that the steering control lever is in the NEUTRAL position.
- Make sure that the implement control lever is in the HOLD position.
- Record low-pressure standby at pressure port (HA). Low-pressure standby should be a maximum of
3600 kPa (520 psi) .Note: Low-pressure standby occurs when the engine is running and the implement control levers are in HOLD position. Low-pressure standby is not adjustable. If low-pressure standby is not within the specified limit, perform the test procedure for margin pressure. If necessary, then perform the adjustment procedure for margin pressure.
Test Preparation - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure
- Move the machine to a smooth horizontal location.
- Lower all the implements.
- Shut off the engine.
- Turn the key to the ON position. Make sure that the implement lockout switch is turned to the UNLOCKED position. Move the implement control levers to all positions several times to release any pressure in the hydraulic system.
Show/hide table
Illustration 5 g03665626 (HA) Implement pump pressure Show/hide table
Illustration 6 g03665629 (HB) Load sensing signal pressure - Pressure port (HA) is located behind the access door on the right fender of the operators station. Pressure port (HB) is on implement pump controller under the cab floor pan.
- Attach one set of tooling (A) to pressure port (HA) and one set of tooling (A) to pressure port (HB). Pressure port (HA) measures the pump discharge pressure. Pressure port (HB) measures the pressure of the load sensing signal.
Note: The load sensing signal is the highest signal that is produced by any of the implement control valves. This signal represents the single greatest load that is being placed on the hydraulic system. The load sensing signal adjusts the pump output to a value that is equal to the load sensing signal pressure plus the margin pressure. Margin pressure is equal to the spring force of the margin spring in the flow compensator valve.
Note: The pump discharge pressure should be equal to the pressure of the load sensing signal plus margin pressure. Margin pressure should be equal to the spring force of the margin spring that is in the flow compensator valve that is on the implement pump. Refer to Table 1 for the correct margin pressure for your machine.
Test Procedure - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure
- Perform the steps in the "Test Preparation - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure" and then continue to the following steps.
- Start the engine. Warm the hydraulic oil to a minimum temperature of
65° C (150° F) . - Operate the engine at HIGH IDLE. Make sure that the steering control lever is in the NEUTRAL position.
- Raise the blade.
Note: The bulldozer control lever should be moved to about 25% of the total travel distance.
- Record the pressure at pressure ports (HA) and (HB) as the blade is being raised.
Note: The margin pressure is the difference between pump discharge pressure (HA) and the pump signal pressure (HB). Margin pressure should be
2100 ± 100 kPa (305 ± 15 psi) . - If the margin pressure is within the specified limit, the test is complete.
- If the margin pressure is not within the specified limit, perform the adjustment procedure in "Adjustment Procedure - Margin Pressure".
Test Preparation - High-Pressure Cutoff
- Move the machine to a smooth horizontal location.
- Lower all the implements.
- Shut off the engine.
- Turn the key to the ON position. Make sure that the implement lockout switch is turned to the UNLOCKED position. Move the implement control levers to all positions several times to release any pressure in the hydraulic system.
Show/hide table
Illustration 7 g03665626 Show/hide table
Illustration 8 g03665629 - Pressure port (HA) is located behind the access door on the right fender of the operators station. Pressure port (HB) is on implement pump controller under the cab floor pan.
- Attach one set of tooling (A) to pressure port (HA) and one set of tooling (A) to pressure port (HB). Pressure port (HA) measures the pump discharge pressure. Pressure port (HB) measures the pressure of the load sensing signal.
Note: The load sensing signal is the highest signal that is produced by any of the implement control valves. This signal represents the single greatest load that is being placed on the hydraulic system. The load sensing signal adjusts the pump output to a value that is equal to the load sensing signal pressure plus the margin pressure. Margin pressure is equal to the spring force of the margin spring in the flow compensator valve.
Note: The pump discharge pressure should be equal to the pressure of the load sensing signal plus margin pressure. Margin pressure should be equal to the spring force of the margin spring that is in the flow compensator valve that is on the implement pump. Refer to Table 1 for the correct margin pressure for your machine.
Test Procedure - High-Pressure Cutoff
- Perform the steps in the "Test Preparation - High-Pressure Cutoff" and then continue to the following steps.
- Start the engine. Warm the hydraulic oil to a minimum temperature of
65° C (150° F) . - Operate the engine at HIGH IDLE. Make sure that the steering control lever is in the NEUTRAL position.
Note: Do not hold the machine in the STALL CONDITION for more than 15 seconds at a time.
- With the engine at HIGH IDLE, move the ripper control lever to the maximum LIFT position. After the cylinder is at the end of the stroke, the implement pump is at the STALL CONDITION.
Note: If the machine is not equipped with a ripper, stall the tilt cylinders.
- Record high-pressure cutoff at pressure port (HA). High-pressure cutoff should be
19300 ± 350 kPa (2800 ± 50 psi) . Refer to Table 1 for the correct high-pressure cutoff for your specific machine. - If the pressure is within the specified limit, the test is complete. If the pressure is not within the specified limit, perform the adjustment procedure in "Adjustment Procedure - High-Pressure Cutoff".
Adjustment Procedure - High-Pressure Cutoff
- Perform the Steps in "Test Procedure - High-Pressure Cutoff" and continue to the following step.
- Remove the floorplate in front of the operators seat in the cab.
Show/hide table
Illustration 9 g02312053 (1) Adjustment screw for high-pressure cutoff
(2) Locknut
(3) Adjustment screw for margin pressure
(4) Locknut - Loosen locknut (2) while you hold adjustment screw (1) in place.
- Turn adjustment screw (1) clockwise to increase the pressure at pressure port (HA) or turn adjustment screw (1) counterclockwise to decrease the pressure at pressure port (HA).
- High-pressure cutoff should be
19300 ± 350 kPa (2800 ± 50 psi) . Refer to Table 1 for the correct high-pressure cutoff for your machine. - Restart the engine and retest the pressure.
- After the pressure is adjusted within the specified limit, tighten locknut (2) to a torque of
21 N·m (15 lb ft) . Make sure that you hold adjustment screw (1) in place. - Check the pressure at pressure port (HA) again. When the pressure is at the specified limit, the adjustment procedure is complete.
Note: The High-Pressure Cutoff adjustment and the Margin Pressure adjustment influence each other. Whenever you adjust one pressure, always check the other pressure and then make any necessary adjustment.
Adjustment Procedure - Margin Pressure
- Perform the Steps in "Test Procedure - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure" and then continue to the following Step.
- Remove the floorplate in front of the operators seat in the cab.
Show/hide table
Illustration 10 g02312053 (1) Adjustment screw for high-pressure cutoff
(2) Locknut
(3) Adjustment screw for margin pressure
(4) Locknut - Loosen locknut (4) while you hold adjustment screw (3) in place.
- Turn adjustment screw (3) clockwise to increase the margin pressure or turn adjustment screw (3) counterclockwise to decrease the margin pressure.
- Perform the steps in "Test Procedure - Load Sensing Signal, Pump Discharge Pressure, and Margin Pressure" to check the margin pressure.
- If the margin pressure is
2100 ± 100 kPa (305 ± 15 psi) , tighten locknut (4) to a torque of21N·m (15 lb ft) . Make sure that you hold adjustment screw (3) in place. - Check the margin pressure again. If the margin pressure is within the specified limit, the adjustment procedure is complete.
Note: The High-Pressure Cutoff adjustment and the Margin Pressure adjustment influence each other. Whenever you adjust one pressure, always check the other pressure and then make any necessary adjustment.