| 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, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
THIS TEST IS DESIGNED TO DETERMINE IF THE PISTON PUMP (WORK TOOL) IS OPERATING WITHIN DESIGN SPECIFICATIONS. THIS TEST SHOULD BE PERFORMED ONLY IF ALL CYLINDER CYCLE TIMES ARE TOO SLOW. REFER TO Testing and Adjusting, "Lift and Tilt Cylinder Speed - Check" FOR THE CYLINDER CYCLE TIMES.
For any pump test, the pump flow at 690 kPa (100 psi) will be larger than the pump flow at 6900 kPa (1000 psi) if the pump is operating at the same rpm. The pump flow is measured in L/min (US gpm).
The difference between the pump flow of two operating pressures is the flow loss.
Note: The values in the examples are not set values for any specific pump or for any specific pump condition. See the Specification for the pump flow of a new pump at 690 kPa (100 psi) and at 6900 kPa (1000 psi).
| Method of determining flow loss | ||
| Pump flow at 690 kPa (100 psi) |
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| - | Pump flow at 6900 kPa (1000 psi) |
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| Flow loss | ||
| Example of determining flow loss | ||
217.6 L/min (57.5 US gpm) |
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| - | 196.8 L/min (52.0 US gpm) |
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20.8 L/min (5.5 US gpm) |
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Flow loss that is expressed as a percentage of pump flow is used as a measure of pump performance.
| Method of determining percent of flow loss | ||||
| Flow loss (L/min or US gpm) | × | 100 | = | Percent of flow loss |
| Pump flow at 690 kPa (100 psi) |
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| Example of determining percent of flow loss | ||||
20.8 L (5.5 US gal) |
× | 100 | = | 9.5% |
217.6 L/min (57.5 US gpm) |
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Machine Test for the Piston Pump for the work Tools
| REQUIRED TOOLS | ||
| Part Number | Description | Quantity |
| 7M-8485 | O-Ring Seals | 2 |
| 6V-8638 | Seal Connectors | 2 |
| 6V-8633 | Seal Connectors | 2 |
| 6V-8398 | O-Ring Seals | 4 |
| 8T-7099 | Couplings | 2 |
| 8T-7101 | Couplings | 2 |
| 6V-1154 | Hose | 1220 mm (48 inch) |
| 9X-8408 | Couplings | 2 |
| 6V-8398 | O-Ring Seals | 2 |
| 3D-2824 | O-Ring Seals | 2 |
| 4C-9912 | Flow Meter | 1 |
| 187-3225 | Coupling | 1 |
| 187-3226 | Coupling | 1 |
| 153-2995 | Coupling | 1 |
| 153-2994 | Coupling | 1 |
| 177-7860 | Hoses | 2 |
| 8T-0860 | Pressure Gauge | 2 |
| 6V-4143 | Couplers | 4 |
| 6V-3989 | Fittings | 2 |
Before you start the pump flow test, the 6V-1154 Hose, the 8T-7101 Coupling, and the 8T-7099 Coupling must be assembled. Cut the 6V-1154 Hose into two equal pieces. Attach an 8T-7101 Coupling to one end of each hose. Attach an 8T-7099 Coupling to the second end of each hose.
To test the rate of flow in the auxiliary hydraulic circuit, assemble the needed tools. Install a 3D-2824 O-Ring Seal in both ends of the 4C-9912 Flow Meter. Install a 9X-8408 Connector in both ends of the flow meter. Install a 6V-8398 O-Ring Seal in the end of each 9X-8408 Connector .
Place the 6V-8398 O-Ring Seals into the 8T-7099 Couplings. Install the 6V-8638 Seal Connectors. Install a 7M-8485 O-Ring Seal onto the seal connectors. Attach the 153-2995 Coupling to one end of the assembly. Attach the 153-2994 Coupling to the assembly.
- Raise the cab. For the 228 Skid Steer Loader, refer to the Operation and Maintenance Manual, SEBU7207, "Cab Support Operation". For the 248 Skid Steer Loader, refer to the Operation and Maintenance Manual, SEBU7255, "Cab Support Operation".
- Attach a 6V-3989 Fitting to each gauge.
- Attach one hose to the pressure port (1) on the piston pump (work tool). Attach an 8T-0860 Pressure Gauge to the other end of the hose.
 | |
| Illustration 1 | g00707421 |
- Attach the second hose to the pressure port (2) on the bank valve. Attach an 8T-0860 Pressure Gauge to the other end of the hose.
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| Illustration 2 | g00707423 |
- Secure the hydraulic line so that the pressure gauges can be viewed by the operator during the test.
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| Illustration 3 | g00679450 |
- Lower the cab.
Install the flow meter on the auxiliary hydraulic circuit. Fasten the seat belt. Start the engine. Run the engine at HIGH idle. Measure the pump flow at 690 kPa (100 psi) and at 6900 kPa (1000 psi). Use these values in the formula in Table 6.
| Pump flow at 690 kPa (100 psi) |
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| - | Pump flow at 6900 kPa (1000 psi) |
× | 100 | = | Percent of flow loss |
| Pump flow at 690 kPa (100 psi) |
The maximum amount of flow loss for the pump is 7 percent.
Fasten the seat belt. Start the engine. Run the engine at HIGH idle. Note the pressure on both gauges. Standby pressure is the difference between the two pressures when the hydraulics are not active. On the 228 Skid Steer Loader, the pressure at the bank valve should be 23000 ± 700 kPa (3336 ± 102 psi). On the 228 Skid Steer Loader, the pressure at the piston pump (work tool) should be 22000 ± 2000 kPa (3191 ± 290 psi).
On the 248 Skid Steer Loader, the pressure at the bank valve should be 29000 ± 700 kPa (4206 ± 102 psi). On the 248 Skid Steer Loader, the pressure at the piston pump (work tool) should be 27000 ± 2000 kPa (3916 ± 290 psi).
On both the 228 Skid Steer Loader and the 248 Skid Steer Loader, the standby pressure should be 2900 ± 300 kPa (421 ± 44 psi).
Press the right side of the control switch for the auxiliary hydraulic circuit. Oil will flow to the top line in the auxiliary circuit. Note the rate of flow. Note the pressure on both gauges. Press the left side of the control switch for the auxiliary hydraulic circuit. Oil will flow to the bottom line in the auxiliary circuit. Note the rate of flow. Note the pressure on both gauges.
Margin pressure is the difference between the two pressures when the hydraulics are active. On the 228 Skid Steer Loader, the pressure at the bank valve should be 23000 ± 700 kPa (3336 ± 102 psi). On the 228 Skid Steer Loader, the pressure at the piston pump (work tool) should be 22000 ± 2000 kPa (3191 ± 290 psi).
On the 248 Skid Steer Loader, the pressure at the bank valve should be 29000 ± 700 kPa (4206 ± 102 psi). On the 248 Skid Steer Loader, the pressure at the piston pump (work tool) should be 27000 ± 2000 kPa (3916 ± 290 psi).
On both the 228 Skid Steer Loader and the 248 Skid Steer Loader, the margin pressure should be 2400 ± 200 kPa (348 ± 29 psi).
On the 228 Skid Steer Loader, the flow rate should be 58 ± 4 L/min (15.3 ± 1.1 US gpm). On the 248 Skid Steer Loader, the flow rate should be 77 ± 5 L/min (20.3 ± 1.3 US gpm).
Remove the flow meter from the auxiliary hydraulic circuit. Remove the seal connectors and couplings. Install the 6V-8633 Seal Connectors. Install a 7M-8485 O-Ring Seal onto the seal connectors. Attach the 187-3225 Coupling to one end of the assembly. Attach the 187-3226 Coupling to the assembly.
Install the flow meter on the high flow auxiliary circuit. Fasten the seat belt. Start the engine. Run the engine at HIGH idle. Note the pressure on both gauges. Standby pressure is the difference between the two pressures when the hydraulics are not active. On the 228 Skid Steer Loader, the pressure at the bank valve should be 23000 ± 700 kPa (3336 ± 102 psi). On the 228 Skid Steer Loader, the pressure at the piston pump (work tool) should be 22000 ± 2000 kPa (3191 ± 290 psi).
On the 248 Skid Steer Loader, the pressure at the bank valve should be 29000 ± 700 kPa (4206 ± 102 psi). On the 248 Skid Steer Loader, the pressure at the piston pump (work tool) should be 27000 ± 2000 kPa (3916 ± 290 psi).
On both the 228 Skid Steer Loader and the 248 Skid Steer Loader, the standby pressure should be 2900 ± 300 kPa (421 ± 44 psi).
Fasten the seat belt. Start the engine. Run the engine at HIGH idle. Press the left side of the control switch for the high flow auxiliary circuit. Oil will flow to the top line in the high flow auxiliary circuit. Note the rate of flow. Note the pressure on both gauges. Press the right side of the control switch for the high flow auxiliary circuit. Oil will flow to the bottom line in the auxiliary circuit. Note the rate of flow. Note the pressure on both gauges.
Margin pressure is the difference between the two pressures when the hydraulics are active. On the 228 Skid Steer Loader, the pressure at the bank valve should be 23000 ± 700 kPa (3336 ± 102 psi). On the 228 Skid Steer Loader, the pressure at the piston pump (work tool) should be 22000 ± 2000 kPa (3191 ± 290 psi).
On the 248 Skid Steer Loader, the pressure at the bank valve should be 29000 ± 700 kPa (4206 ± 102 psi). On the 248 Skid Steer Loader, the pressure at the piston pump (work tool) should be 27000 ± 2000 kPa (3916 ± 290 psi).
On both the 228 Skid Steer Loader and the 248 Skid Steer Loader, the difference between the pressure at the bank valve and the pressure at the piston pump (work tool) during operation of the high flow auxiliary circuit should be 0 - 1000 kPa (0 - 145 psi).
On the 228 Skid Steer Loader and 248 Skid Steer Loader, the rate of flow for the high flow auxiliary circuit should be 130 ± 10 L/min (34.3 ± 2.6 US gpm).
If the pressures are not within specifications, adjust the pressure compensation valve. Repeat the adjustments until the pressures are within specifications.
If the pressures are within specifications, perform the "Line Relief Valve - Test and Adjust" procedure in this module.
Bench Test for the Gear Pump
THIS TEST IS DESIGNED TO DETERMINE IF THE GEAR PUMP IS OPERATING WITHIN DESIGN SPECIFICATIONS.
If the test bench can be run at 6900 kPa (1000 psi) and at full pump rpm, use the formula in Table 7 to determine the percent of flow loss.
If the test bench can not be run at 6900 kPa (1000 psi) or at full pump rpm, run the pump shaft at 1000 rpm. Measure the pump flow at 690 kPa (100 psi) and at 6900 kPa (1000 psi). Use these values in the top portion of the formula in Table 7. For the bottom part of the formula, run the pump shaft at 2000 rpm. Measure the pump flow at 690 kPa (100 psi).
| Pump flow at 690 kPa (100 psi) |
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| - | Pump flow at 6900 kPa (1000 psi) |
× | 100 | = | Percent of flow loss |
| Pump flow at 690 kPa (100 psi) and at 2000 rpm |
The maximum amount of flow loss for the pump is 7 percent.
Refer to Specifications, RENR2858-01, "Gear Pump" for the specifications for the gear pump for the 228 Skid Steer Loader. Refer to Specifications, RENR2873-01, "Gear Pump" for the specifications for the gear pump for the 248 Skid Steer Loader.