- Mini Hydraulic Excavator:
- 301.6C (S/N: JBB1-UP)
- 301.8C (S/N: JSB1-UP)
- 302.5C (S/N: GBB1-UP)
- 305 (S/N: DSA1-UP; DGT1-UP)
- 301.8C (S/N: JSB1-UP)
Introduction
Revision     | Summary of Changes in REHS2804     |
02     | Updated Contact Information in introduction.     |
Added ""Canceled Part Numbers and Replaced Part Numbers" " section to document. | |
Added REHS1761 "Required Tooling for Bench Testing Hydraulic Components" to ""References" " section of document. |
© 2012 Caterpillar All Rights Reserved. This guideline is for the use of Caterpillar Dealers only. Unauthorized use of this document or the proprietary processes therein without permission may be violation of intellectual property law.
This Special Instruction includes test procedures for piston pumps. This Special Instruction also provides specifications. The technician should have a good understanding of hydraulic piston pumps. The technician should be educated in the operation of the hydraulic test bench. The test benches in this document are available through the Caterpillar Dealer Service Tools. Gather all necessary tooling before you need to hook up the pump. Some of the required tooling appears in a table at the end of this document. There are many possible variations of tooling that could be used. Not every possible variation can be listed.
For questions or additional information concerning this guideline, submit a feedback form in the Service Information System website. In order to address an urgent need, use the following to relay your request to Caterpillar Repair Process Engineering:
- Cat Dealer Technical Communicator
- Dealer Solution Network
- Cat Technical Representative
- Knowledge Network (online)
Canceled Part Numbers and Replaced Part Numbers
This document may not include all Canceled part numbers and replaced part numbers. Use NPR on SIS for information about Canceled part numbers and replaced part numbers. NPR will provide the current part numbers for replaced parts.
Safety
Personal injury or death can result from improperly checking for a leak. Always use a board or cardboard when checking for a leak. Escaping air or fluid under pressure, even a pin-hole size leak, can penetrate body tissue causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. |
Pump test pressures in this guideline may exceed the normal operating range of the hydraulic test hoses utilized when connecting the tested pump to the test bench. However, the order of magnitude of these pressures is significantly below the burst strength of the Caterpillar "XT6" product. High pressure oil can escape through improperly assembled hoses and fittings. High pressure oil can also escape through poorly maintained hoses and fittings. High pressure oil may also leak through hose that has become damaged over the life of the hose due to the pressure levels that occur during test bench operation. Personal injury or death can result from improper hose & fitting inspection or improper hose replacement procedures. Escaping fluid under pressure can penetrate body tissue causing serious injury, and possible death. Thoroughly inspect all testing hoses, fittings, and quick disconnects prior to any testing operation. Check the assembly date tag or hose assembly log date for a hose life indicator. Replace all Test Bench hoses at a minimum of every 2 years or earlier if the hose or fittings appear to be damaged. |
Hot oil and hot components can cause personal injury. Do not allow hot oil or hot components to contact skin. |
Summary
This procedure is specific to the type of pump and the type of control. Refer to the test specifications and the tooling at the end of this document.
Note: A paper copy of this document may not be the latest version. Go to the Service Information System (SIS) in order to view the latest version.
References
References     | |
---|---|
Media Number     | Title     |
REHS1761     | Required Tooling for Bench Testing Hydraulic Components     |
SEBF8810     | Hydraulic Pump, Motor, and Cylinder Bench Test Procedure Reference Manual     |
SEHS8892     | Operating Instructions for Caterpillar 1U-9400 Series Hydraulic Test Center     |
NEHS0563     | Tool Operating Manual for 9U-5000 Series Hydraulic Test Bench     |
Connections for the Caterpillar Hydraulic Test Center
Illustration 1 | g01063311 |
Connections for the Test Center (1) Flow control for discharge (2) "F3" flow meter inlet (3) "F4" flow meter inlet (4) Oil supply from the auxiliary pump (5) "F3" inlet for the flow meter with flow limiter (6) "F3"outlet for the flow meter with pressure control (7) Load sensing pressure (8) Signal pressure (9) "F4" outlet for the flow meter (10) Return to tank (11) Connections for case drain (12) Oil supply |
Illustration 2 | g01063312 |
Control and Gauges for the Test Center (13) Meter for speed and torque (14) Gauge for signal pressure (15) Control for signal pressure (16) Pressure gauge for auxiliary pump (17) Auxiliary pump flow (18) "F3" discharge pressure gauge (19) "F3" discharge flow (20) "F4" discharge pressure gauge (21) "F4" discharge flow (22) Auxiliary pump flow control (23) "F3" margin pressure (24) "F3" Load control for discharge pressure (25) "F4" Load control for discharge pressure |
Connections for the Caterpillar Hydraulic Test Bench
Illustration 3 | g01063314 |
Connections for the Test Bench (26) "Flow meter 1" loop and "Flow meter 2" loop (27) Oil Supply |
Illustration 4 | g01093468 |
Connections for the Test Bench (28) "Flow meter 2" loop (29) "Flow meter 1" loop (30) "Flow meter 2" outlet (31) Signal pressure line (32) "Flow meter 2" inlet (33a) "Flow meter 1" outlet (33b) Auxiliary oil supply outlet (34) Auxiliary oil supply inlet (35) "Flow meter 1" inlet |
Illustration 5 | g01063316 |
Control and Gauges for the Test Bench (36) Auxiliary oil supply pressure (37) Signal pressure (38) Control for signal pressure (39) "Flow meter 1" discharge pressure (40) Control for auxiliary oil supply pressure (41) "Flow meter 2" discharge pressure (42) Auxiliary oil supply control (43) "Flow meter 2" discharge flow (44) Discharge flow for auxiliary pump (45) "Flow meter 1" discharge flow (46) "Flow meter 1" load control (47) Speed and direction control (48) "Flow meter 2" load control |
Port Locations
Illustration 6 | g01200069 |
Typical port locations and adjustments. (49) Suction port (50) Case drain port (51) Pressure port for load sensing (52) Adjustment screw for high-pressure cut (53) Discharge port (54) Adjustment screw for margin pressure |
Pump Setup
Illustration 7 | g01215065 |
Hydraulic schematic (49) Suction port (50) Case drain port (51) Pressure port for load sensing (52) Adjustment screw for high-pressure cut (53) Discharge port (54) Adjustment screw for margin pressure |
Note: Make sure that all fittings and hoses are XT-6 rated.
- Purge all air from the suction line. Loosen the suction hose at the pump until oil leaks from the connection. Tighten the suction hose.
- Connect the discharge ports (51) and (52) to a Tee. Connect the third end of the tee to the flow meter inlet on the test bench.
- Connect one end of an XT-6 hose to the flow meter outlet on the test bench. Connect the other end to the tank.
- Connect discharge port (53) to one side of a Tee. Connect at 8T-0856 Pressure Gauge to the second side. Connect an in-line flow meter to the outlet side of the tee. Refer to Illustration 7 for a schematic of the setup.
- Connect an adjustable needle valve to the end of the in-line flow meter. Return outlet oil to the tank. Refer to Illustration 7 for a schematic of the setup.
- Connect discharge port (54) to one side of a Tee. Connect at 8T-0856 Pressure Gauge to the second side. Connect an in-line flow meter to the outlet side of the tee. Refer to Illustration 7 for a schematic of the setup.
- Connect an adjustable needle valve to the end of the in-line flow meter. Return outlet oil to the tank. Refer to Illustration 7 for a schematic of the setup.
- Fill the pump case with oil before rotating. Pour oil directly into the oil filling port (50) until the case is full. Plug the filling port when complete.
- Do not rotate the pump in the wrong direction. The correct direction of rotation will be stated on the pump. The correct direction of rotation will also be in the test specifications. The direction of rotation is viewed from the input shaft end. Visually check the pump for proper rotation.
Test Procedure
Note: The steps in the procedure correlate with the steps under the test specifications according to your specific part number.
The contamination level of the hydraulic oil in the test bench should be ISO 16/13 or better. The oil in the test bench should be one of the following.
- SAE 10W at 50 °C (122 °F) or
- Mobil DTE-11 at 46 °C (115 °F)
Illustration 8 | g01213014 |
Torque control characteristics (Q) Discharge flow (P) Discharge pressure |
- Start rotating the pump according to the RPM in Step 1 of the test specifications. Listen for abnormal noise. Verify flow from the pump. Verify that all connections are tight. Check for leaks around shaft seals. Check for leaks around the control valve.
Run the pump for at least 5 minutes in order to raise the temperature of the oil and purge the system of air.
- Follow Step 2 in order to verify maximum displacement. Increase the RPM to the value in Step of the test specifications. Record discharge flow. If the discharge flow does not meet specifications, then internally inspect the pump. Increase the discharge pressure via the needle valves on discharge ports (53) and (54). Increase the discharge pressures to the value in Step 2 of the test specifications.
- Increase pump discharge pressure to the value in Step 3 of the test specifications. Measure pump efficiency. Calculate the total loss. If the total loss is higher than the allowable value in Step 3 of the test specifications, the pump may not be mechanically feasible. Steps 3, 4, and 5 will verify the torque control. Compare the flow rates at each step to the values in the test specifications. Refer to Illustration 8 for the characteristics of the torque control.
This is the destroke point. The pump should now be under torque control. Slowly cycle the discharge pressure above and below the value in Step 3 of the test specifications. This will verify the destroke point. The discharge flow should drop as the discharge pressure increases above the value in Step 3 of the test specifications.
Find the total loss. Subtract the discharge flow in Step 3 from the discharge flow in Step 2. The result is the total loss.
Example: "Step 4 flow" 162 L/min (42.8 US gpm) - "Step 3 flow" 158 L/min (41.7 US gpm) = "total loss" 4 L/min (1.1 US gpm). The "max. allowable loss" is 7.2 L/min (1.9 US gpm).
The pump in the example is acceptable because the actual total loss is less than the maximum allowable loss.
- Increase the discharge pressure to the value in Step 4 of the test specifications. The discharge flow should decrease to the value in Step 4 of the test specifications. Record discharge flow. If the discharge flow does not meet specifications, then internally inspect the pump.
- Increase the discharge pressure to the value in Step 5 of the test specifications. The discharge flow should decrease to the value in Step 5 of the test specifications. Record discharge flow. If the discharge flow does not meet specifications, then internally inspect the pump.
Pump test pressures in this guideline may exceed the normal operating range of the hydraulic test hoses utilized when connecting the tested pump to the test bench. However, the order of magnitude of these pressures is significantly below the burst strength of the Caterpillar XT6 product. High pressure oil can escape through improperly assembled hoses and fittings. High pressure oil can also escape through poorly maintained hoses and fittings. High pressure oil may also leak through hose that has become damaged over the life of the hose due to the pressure levels that occur during test bench operation. Personal injury or death can result during adjustment of the high pressure relief valve if recommended hose maintenance practices are not followed. Escaping fluid under pressure can penetrate body tissue causing serious injury, and possible death. Adjustment of the high pressure cut or pressure override valve shall only be performed when the pump is operating at a zero discharge pressure condition. Continuation of the pump test procedure can be resumed when this high pressure adjustment is completed. |
Test Specifications
Part Number     | 208-1112     | ||||
Pump specifications are not available at this time. |
Part Number     | 241-7971     | ||||
Pump Rotation     | Clockwise     | ||||
Step     | 1     | 2     | 3     | 4     | 5     |
RPM     | 600     | 2200     | 2200     | 2200     | 2200     |
Main Pump Discharge Pressure kPa (psi)     | 0     | 0     | 22540 (3270)     | 33320 (4832)     | 41200 (5975)     |
Main Pump Discharge Flow Lpm (gpm)     | 9.5 (2.5)     | 35 (9.3)     | 35 (9.3)     | 22 (5.8)     | 17.5 (4.7)     |
Auxiliary Pump Discharge Pressure kPa (psi)     | 0     | 980 (142)     | 980 (142)     | 980 (142)     | 980 (142)     |
Auxiliary Pump Discharge Flow Lpm (gpm)     | 3.6 (1)     | 13.2 (3.5)     | 13.2 (3.5)     | 13.2 (3.5)     | 13.2 (3.5)     |
Pilot Pump Discharge Pressure kPa (psi)     | 0     | 3400 (493)     | 3400 (493)     | 3400 (493)     | 3400 (493)     |
Pilot Pump Discharge Flow Lpm (gpm)     | 2 (0.6)     | 7.8 (2.1)     | 7.8 (2.1)     | 7.8 (2.1)     | 7.8 (2.1)     |
Pump Loss Lpm (gpm)     | -     | -     | 5 (1.3)     | -     | -     |
Part Number     | 241-7972     | ||||
Pump Rotation     | Clockwise     | ||||
Step     | 1     | 2     | 3     | 4     | 5     |
RPM     | 600     | 2200     | 2200     | 2200     | 2200     |
Main Pump Discharge Pressure kPa (psi)     | 0     | 0     | 17640 (2560)     | 33320 (4832)     | 41160 (5970)     |
Main Pump Discharge Flow Lpm (gpm)     | 16.5 (4.4)     | 61.7 (16.3)     | 61.7 (16.3)     | 30 (8)     | 22 (5.8)     |
Auxiliary Pump Discharge Pressure kPa (psi)     | 0     | 980 (142)     | 980 (142)     | 980 (142)     | 980 (142)     |
Auxiliary Pump Discharge Flow Lpm (gpm)     | 4.9 (1.3)     | 19 (5)     | 19 (5)     | 19 (5)     | 19 (5)     |
Pilot Pump Discharge Pressure kPa (psi)     | 0     | 3400 (493)     | 3400 (493)     | 3400 (493)     | 3400 (493)     |
Pilot Pump Discharge Flow Lpm (gpm)     | 2.1 (0.5)     | 7.5 (2.0)     | 7.5 (2.0)     | 7.5 (2.0)     | 7.5 (2.0)     |
Pump Loss Lpm (gpm)     | -     | -     | 12.0 (3.2)     | -     | -     |
Test Bench Tooling
Part Number     | Mounting Flange     | Drive Adapter     | Suction Adapter     | Discharge Ports     | Oil Filling Port     |
208-1112     | 1U-9127     | 1U-9833     | 1U-9869     | 7/8-14 UNF     | 1/2-14 UNF     |
241-7971     | 1U-9127     | 1U-9836     | 1U-9869     | 9/16-18 UNF     | 1/2-14 UNF     |
241-7972     | 1U-9127     | 1U-9833     | 1U-9869     | 7/8-14 UNF     | 1/2-14 UNF     |