Testing and Adjusting 236B, 246B, 252B and 262B Skid Steer Loaders Hydraulic System Media Number -RENR4867-03 Publication Date -01/11/2009 Date Updated -24/11/2009 Hydrostatic System - Test and Adjust SMCS - 4350-025; 4350-081 Table 1 Required Tools Part number Description Quantity 6V-4143 Quick Connect Coupler 10 177-7861 Hose As 5 6V-3989 Fitting As 6 6V-3966 Fitting As 2 8T-0855 Pressure Gauge 0 to 4000 kpa (580 psi) 3 i03177701 8T-0854 8T-0860 Pressure Gauge 0 to 1000 kpa (145 psi) Pressure Gauge 0 to 40000 kpa (5802 psi) 1 1 186-2613 Pressure Gauge 0 to 70000 kpa (10153 psi) 2 1U-5796 Pressure Differential Tool Gp 1 164-3310 Infrared Thermometer 1 9U-7400 Multitach Tool Gp 1 1U-6605 Reflective Tape 1 7X-2444 Swivel Tee 1
4J-5477 O-Ring Seal 1 5P-2937 O-Ring Adapter 1 3J-7354 O-Ring Seal 1 Install a 6V-4143 Quick Connect Coupler to each end of the 177-7861 Hose As. Install a 6V-3989 Fitting to the 8T-0855. Install a 6V-3989 Fitting to the 8T-0854 Pressure Gauge. You will also need to install a 6V-3989 Fitting to the 186-2613 Pressure Gauge. Install a 6V-3966 Fitting As into both of the 7X-2444 Swivel Tee and the 5P-2937 O-Ring Adapter. Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the power train. 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 Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. Before any tests are performed, prepare the machine. Refer to Testing and Adjusting, "Machine Preparation". Before any tests are performed, visually inspect the complete hydraulic system for oil leaks and damaged parts. Refer to Testing and Adjusting, "Visual Inspection". The tests for the hydraulic system should be done in the following order. In order for the hydrostatic system to function correctly, each component in the system must be set to the correct specifications. Some components must be set prior to the testing of other components. A component that is not set correctly will have an impact on other components in the system.
It is not advisable to bypass preceding tests. Do not perform a test before the tests that precede that test have been done. Table 1 lists the equipment that is needed to perform testing on the hydrostatic system. Equivalent tooling may be substituted. Clearly mark all of the hoses and the corresponding pressure gauges, when the hoses are installed. The hoses and the pressure gauges will be used multiple times in the testing and adjusting procedures. Throughout the entire testing procedure, MB pressure refers to the hydraulic oil pressure in the forward hydrostatic loop. MA pressure refers to the hydraulic oil pressure in the reverse hydrostatic loop. Note: The oil in the hydraulic system must be at an operating temperature of 45 ± 5 C (113 ± 9 F). This temperature range is specified for only the standard oil from the factory. Use the 164-3310 Infrared Thermometer or the equivalent to measure this temperature at the hydraulic filter. In order to increase the hydraulic system temperature, start the engine and operate all hydraulic cylinders for at least five cycles. Move the machine in the forward and reverse directions. Move the work tool through the full range of motion. Baseline for the Hydrostatic System Use cribbing to elevate the machine. The wheels must not touch the ground. 1. 2. 3. Release the hydraulic system pressure. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release" for the correct procedure. Raise the cab. Refer to Operation and Maintenance Manual, "Cab Support Operation" for the correct procedure. Illustration 1 g00788958 (1) Charge pressure tap 4. Install the 177-7861 Hose to the charge pressure tap (1) on the right side of the hydrostatic piston pump. Connect the 8T-0855 Pressure Gauge to the other end of this hose. Place the hose in a visible position.
Illustration 2 g00788976 (2) Speed sensing pressure tap 5. Install the 177-7861 Hose to the speed sensing pressure tap (2). The speed sensing pressure tap is located on the top of the hydrostatic piston pump. Connect the 8T-0855 Pressure Gauge to the other end of this hose. Place the hose in a visible position. Illustration 3 g00592868 6. Install the 9U-7400 Multitach Tool Gp on the rear frame and position the sensor in order to pick up the reflective tape on the crankshaft pulley.
Illustration 4 g00592874 7. 8. 9. 10. Install the 9U-7400 Multitach Tool Group in the engine compartment and position the sensor in order to pick up the reflective tape on the fan blade. Route the test hoses so that the cab does not rest on the hoses. Lower the cab. Ensure that the test hoses and cables do not contact the tires. Securely bolt the cab to the frame. Start the engine and operate each work tool function. Operate the hydrostatic drive forward and operate the hydrostatic drive rearward until the hydraulic system reaches an operating temperature of 45 ± 5 C (113 ± 9 F). Set the engine to LOW IDLE and verify the engine RPM. Determine if the engine RPM is within the proper specification. If the engine RPM for LOW IDLE is incorrect, perform the following adjustments to the cable assembly of the governor control: Set the throttle to the HIGH IDLE position. Install the cable assembly to the engine so the cable nuts can be positioned and tightened in order to set the throttle's bracket. The bracket must make contact with the HIGH IDLE stop. Move the throttle to the LOW IDLE position. Adjust the 6V-7357 Bolt until the low idle stop remains in slight contact with the bracket. Tighten the 5C-2890 Nut in order to lock the bolt in place. Note: LOW IDLE and HIGH IDLE have been preset at the factory. The setting of the LOW IDLE and the HIGH IDLE on these engines should not be adjusted. Adjusting the setting can void the warranties on the fuel injection pump and the engine. Adjusting the setting can invalidate the standards for emissions. Adjustment of the LOW IDLE and the HIGH IDLE should be made only by trained personnel. The LOW IDLE and HIGH IDLE for most engine applications is given in the Systems Operation, "Engine Design". Some engine applications may have a different LOW IDLE and HIGH IDLE. Note: Verify the engine rpm for the LOW IDLE and the HIGH IDLE by referring to the Technical Marketing Information (TMI) or to the Fuel Setting and Related Information Fiche.
Model Table 2 Low Idle Engine RPM 236B/ 246B/ 252B/ 262B 1000 ± 50 RPM 11. Record the following items at LOW IDLE: engine RPM, charge pressure and speed sensing pressure. Model Oil Temperature Range 45 ± 5 C (113 ± 9 F) Table 3 Charge Pressure Pressure for Speed Sensing 236B/ 246B/ 252B/ 262B 3100 ± 200 kpa (450 ± 29 psi) 950 ± 200 kpa (138 ± 29 psi) 12. Increase the engine speed to HIGH IDLE. If the engine speed for HIGH IDLE is incorrect, perform the following checks: Set the throttle to the HIGH IDLE position. Install the cable assembly to the engine so the cable nuts can be positioned and tightened in order to set the throttle's bracket. The bracket must make contact with the high idle stop. Move the throttle to the LOW IDLE position. Adjust the 6V-7357 Bolt until the LOW IDLE stop remains in slight contact with the bracket. Tighten the 5C-2890 Nut in order to lock the bolt in place. Note: Low idle and high idle have been preset at the factory. The setting of the LOW IDLE and the HIGH IDLE on these engines should not be adjusted. Adjusting the setting can void the warranties on the fuel injection pump and the engine. Adjusting the setting can invalidate the standards for emissions. Adjustment of the LOW IDLE and the HIGH IDLE should be made only by trained personnel. LOW IDLE and HIGH IDLE for most engine applications is given in the Systems Operation, "Engine Design". Some engine applications may have a different LOW IDLE and HIGH IDLE. Model Table 4 High Idle Engine RPM 236B/ 246B/ 252B/ 262B 2860 ± 50 RPM
For machines with a standard fan, record the fan RPM at HIGH IDLE engine 13. RPM. Model Table 5 Maximum Fan RPM 236B/ 252B 2000 ± 50 RPM 246B/ 262B 2450 ± 50 RPM 14. For machines with a demand fan, perform the following: a. Set the engine RPM to HIGH IDLE and install a jumper connector into the plug of the control module for the demand fan. Allow the completion of the calibration of the fan. The fan will stabilize. Record the calibrated fan RPM. Model Table 6 Calibrated Fan RPM 246B/ 262B 1764 ± 50 RPM Remove the jumper connector from the plug of the control module for the b. fan. c. Disconnect the hydraulic oil temperature sensor at the fan motor. Record the maximum fan RPM. Model Table 7 Maximum Fan RPM 246B/ 262B 2400 ± 50 RPM 15. Set the engine RPM on all machines. Refer to the table below. Record the speed sensing pressure and the charge pressure. Table 8 Model Engine RPM Speed Sensing Pressure Charge Pressure Oil Temperature Range 45 ± 5 C (113 ± 9 F) 236B/ 246B/ 252B/ 262B 2300 ± 25 RPM 2000 ± 150 kpa (290 ± 22 psi) 3225 ± 200 kpa (468 ± 29 psi) Speed Sensing Valve Adjustment If the speed sensing pressure is low at low idle, perform the following adjustment.
Illustration 5 g01422109 Remove cap (A) from the speed sensing valve.
Illustration 6 g01422113 Adjustment to the speed sensing valve Loosen locknut (C) on the speed sensing valve. Turn the adjustment screw (B) on the speed sensing valve counterclockwise. If the speed sensing pressure is high at low idle, perform the following adjustment. Turn the adjustment screw (B) on the speed sensing valve clockwise. If the speed sensing pressure is low at high idle, perform the following adjustments. Turn the adjustment screw (B) on the speed sensing valve counterclockwise. Note: If any adjustments have been made to the speed sensing valve, then repeat the test until the values are within specifications. Tighten locknut (C) on the speed sensing valve.
Start To Move Test Perform the start to move test in order to verify that forward and reverse machine movement begins within specified time after the operator initiates a command. Perform the Hydrostatic System Baseline Test before testing for start to1. move. 2. 3. 4. Start the engine and operate each work tool function. Operate the hydrostatic drive forward and operate the hydrostatic drive rearward. Operate until the hydraulic system reaches an operating temperature of 45 ± 5 C (113 ± 9 F). Set the engine speed to LOW IDLE. Quickly move the joystick control for drive into forward to the 12 o'clock position. Capture the time until the machine moves. Use a stopwatch to measure the specifications. Immediately return the joystick to the neutral position. Repeat four times. Calculate the average in order to determine the Forward 5. Start to Move time. 6. Quickly move the joystick control for drive into rearward to the 6 o'clock position. Capture the time until the machine moves. Use a stopwatch to measure the specifications. Immediately return the joystick to the neutral position. Repeat four times. Calculate the average in order to determine the Forward 7. Start to Move time. Table 9 Model Start to Move Forward. Start to Move Reverse. 236B/ 246B/ 252B/ 262B 1 second max 1.5 seconds max Pump Neutral Position Test Perform the test for the neutral position of the pump in order to make sure that the piston pump is synchronized. If the pump is not synchronized, the machine could drift or the machine could move with the pilot operated hydraulic control ( hydrostatic) in the NEUTRAL position. If the pump is not synchronized, the wheel on one side of the machine could start to move before the wheel on the other side of the machine starts to move. Note: If the left wheel and the right wheel start to move at the same time, this test is not required. 1. 2. 3. Use cribbing to elevate the machine. The wheels must not touch the ground. Make sure that all hoses are out of the way of the rotating wheels. Sit in the operator's seat. Fasten the seat belt and lower the armrest. Start the engine and run the engine at LOW idle. 4. Move the pilot operated hydraulic control ( hydrostatic) slowly forward. Check that the left wheel and the right wheel start to move at the same time. If the left wheel and the right wheel
start to move at the same time, proceed to the "Maximum Runout"test. If the left wheel and the right wheel do not start to move at the same time, proceed to step 5. 5. Raise the cab. Refer to Operation and Maintenance Manual, "Cab Support Operation" for the proper procedure. Note: Perform the test on rotating group 2 of the piston pump first. Rotating group 2 powers the piston motor which is on the right side of the machine. Rotating group 2 is farthest from the engine. Illustration 7 g01116389 (4) Neutral adjusting bolt for rotating group 2 (5) Neutral adjusting bolt for rotating group 1 (6) MA Port for rotating group 2 (7) MA Port for rotating group 1 6. Remove the plug from the MA port for rotating group 2 (6). Install 6V-3965 Fitting with 3J- 1907 O-Ring Seal into the MA port for rotating group 2 (6). Install 8T-0860 Pressure Gauge (0
to 40000 kpa) to the MA port for rotating group 2 (6) with the following items: 6V-3989 Fitting, two 6V-4143 Quick Connect Couplers and 177-7860 Hose. Illustration 8 g01116394 (8) MB Port for rotating group 2 (9) MB Port for rotating group 1 7. 8. Install 8T-0860 Pressure Gauge (0 to 40000 kpa) to the MB port for rotating group 2 (8) with the following items: 6V-3989 Fitting, two 6V-4143 Quick Connect Couplers and 177-7860 Hose. Place the two gauges in an easily visible position. Lower the cab. Route the test hoses so that the cab does not rest on any of 9. the hoses. 10. 11. 12. Fasten the seat belt and lower the armrest. Start the engine and run the engine at LOW idle. Raise the cab.
Loosen the locknut for the neutral adjusting bolt. Do not use an impact13. socket. 14. 15. Turn neutral adjustment screw for rotating group 2 (4) clockwise. Mark the location of the neutral adjusting bolt when the MB pressure begins to increase. Turn neutral adjustment screw (4) counterclockwise. Mark the location of the neutral adjusting bolt when the MA pressure begins to increase. Turn the neutral adjustment screw (4) midway between the two marks.16. 17. 18. Hold the neutral adjustment screw (4) in position as you tighten the locknut to a torque of 30.0 ± 1.5 N m (22.1 ± 1.1 lb ft). Lower the cab. Note: In the next step, the wheels will rotate. Make sure that all hoses are out of the way of the rotating wheels. 19. 20. Move the pilot operated hydraulic control ( hydrostatic) slowly forward. Check that the left wheel and the right wheel start to move at the same time. If the wheels do not start to move at the same time, then repeat this adjustment procedure for rotating group 1. Maximum Runout Illustration 9 g00560554 Use cribbing to elevate the machine. 2. Use cribbing to elevate the machine. The wheels must not touch the ground. 1. Release the hydraulic system pressure. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release" for the correct procedure.
3. Raise the cab. Refer to Operation and Maintenance Manual, "Cab Support Operation" for the correct procedure. Illustration 10 g00788958 (1) Charge pressure tap 4. Install the 177-7861 Hose to the charge pressure tap (1) on the right side of the hydrostatic piston pump. Connect an 8T-0855 Pressure Gauge to the other end of this hose. Place the hose in a visible position. Illustration 11 g00788976 (2) Speed sensing pressure tap 5. Install the 177-7861 Hose to the speed sensing pressure tap (2) on the top of the hydrostatic piston pump and connect an 8T-0855 Pressure Gauge to the other end of this hose.
Illustration 12 g01364143 6. Install the 177-7861 Hose to the MB1 (3) and the MB2 (4) onto the pressure ports on the right side of the hydrostatic piston pump. Connect 186-2613 Pressure Gauge to the other end of these hoses and place the hoses in a visible position. Illustration 13 g00592868 7. Install the 9U-7400 Multitach Tool Gp on the rear frame. Position the sensor in order to read the reflective tape on the crankshaft pulley. 8. Route the test hoses so that the cab does not rest on the hoses. Lower the cab. Ensure that the test hoses and cables do not contact the tires. Securely bolt the cab to the frame.
Illustration 14 g00726910 The illustration shows the correct placement of the reflective tape. 9. 10. 11. 12. One wheel on each side of the machine will be checked for correct maximum runout. Apply 1U -6605 Reflective Tape to the wheel studs of each wheel at 90 intervals. Set the sensor to read the tape strips. Start the machine and set the engine to HIGH IDLE. Verify that the hydraulic oil temperature is within the specification of 45 ± 5 C (113 ± 9 F). Operate the left hydraulic pilot control valve in the forward direction. Hold the hydraulic pilot control valve in this position. Use the 9U-7401 Multitach Tool Gp to record the wheel speed. Record the wheel speeds for both sides of the machine. Divide the indicated wheel speed by four in order to calculate the actual wheel speed. Model Table 10 Wheel Speed 236B/ 246B 79 ± 6 RPM 236B and 246B (slow speed) 66 ± 6 RPM 252B/ 262B 74 ± 5 RPM 252B and 262B (slow speed) 61 ± 5 RPM Note: If the wheels are not within 1 RPM of each other, perform the maximum displacement stop adjustment procedure. The hystat displacement stops control of the maximum stroke of the swashplate in each rotating group in the forward direction. Maximum Displacement Stop Adjustment Procedure 1. To reduce the right wheel speed runout, turn the maximum displacement adjustment screw clockwise. To increase the right side wheel speed runout, turn the maximum displacement
adjustment screw counterclockwise. The right side maximum displacement adjustment screw is located on the right side of the hydrostatic pump farthest from the engine. Make adjustments by turning the screw in increments of 1/8 of a turn and recheck using the maximum runout test. 2. 3. To reduce the left side wheel speed runout, turn the maximum displacement adjustment screw clockwise. To increase the left side wheel speed runout, turn the maximum displacement adjustment screw counterclockwise. The left side maximum displacement adjustment screw is located on the right side of the hydrostatic pump. Make adjustments by turning the screw in increments of 1/8 of a turn and recheck using the maximum runout test. Once the right and left wheel speeds are within the specification, tighten the adjustment screw and the adjustment screw locknut to 22 ± 1 N m (16.2 ± 0.7 lb ft) and install a 6E-5060 Cap As. Stall Test Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the power train. Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand. The test can be used in order to identify low power problems with the engine. The test is also used to identify the crossover relief valves that may be malfunctioning. 1. Raise the cab. Refer to Operations and Maintenance Manual, "Cab Support Operation" for the correct procedure.
Illustration 15 g00790186 (1) Electrical connection (2) Brake solenoid 2. 3. Position the machine against an object that will prevent the machine from moving. It is possible to drive through the brakes. Disconnect the electrical connection (1) for the brake solenoid (2). The 6V-3121 Multitach or the 9U-7400 Multitach Tool Group should still be installed on the machine. If a unit is not installed on the machine, reinstall a multitach. Illustration 16 g01365563 (3) Pressure tap MB for rotating group 1 (4) Pressure tap MB for rotating group 2 4. The two 177-7861 Hose Assemblies should still be attached to the MB pressure ports (3) and (4). If the hose assemblies are not installed on the machine, reinstall the hose assemblies.
5. 6. 7. 8. 9. Route the test hoses and cables so that the cab will not rest on the hoses and cables. Properly secure the cab. Sit in the operator's seat and fasten the seat belt. Lower the armrest. Start the engine and run the engine at LOW IDLE. Slowly increase the engine speed to HIGH IDLE. Push the pilot operated hydraulic control to the FORWARD position until the engine RPM stabilizes. Note: Do not continue to stall the hydrostatic system for more than 15 seconds. Damage to the machine may result. Note: The wheels should not spin. If the wheels spin, refer to the Testing and Adjusting, "Brake Test". Record the engine stall speed. Record the MB1 and MB2 pressure values. 10. Table 11 Model Engine Stall MB1 Pressure MB2 Pressure 236B/ 246B/ 252B/ 262B 2700 ± 200 RPM 38300 ± 2000 kpa (5555 ± 290 psi) 38300 ± 2000 kpa (5555 ± 290 psi) If the engine stall RPM is not correct, refer to the troubleshooting section. If the MB pressures are not within the specification, the crossover relief valves may need to be adjusted. Refer to the procedure below. 1. Remove the cap of the crossover relief valve that is not within the specification. Remove the spring and the crossover relief valve. Illustration 17 g01365567
2. 3. Place crossover relief valve (5) into a vise. Turn the set screw (6) counterclockwise in order to loosen the setscrew. Illustration 18 g01365572 4. Place retainer (7) of the crossover relief valve in a vise. Turn adjustment screw (8) in order to adjust the relief pressure. Turn the adjustment screw clockwise in order to increase the pressure or turn the adjustment screw counterclockwise in order to decrease the pressure. One full turn of the adjustment screw is approximately 6400 kpa (928 psi). Note: When you adjust the crossover relief valve to decrease the pressure, turn the adjustment screw for an additional 1/4 turn past the estimated adjustment setting. Then, turn the adjustment screw clockwise for 1/4 turn. 5. 6. Tighten setscrew (6) to a torque of 6.5 N m (58 lb in). Install crossover relief valve (5), the spring, and the cap. Tighten the cap to a torque of 160 ± 10 N m (118 ± 7 lb ft). Double Stall Test The test will determine if engine performance is low. Note: The 6V-3121 Multitach or the 9U-7400 Multitach Tool Group should still be installed on the machine. If the unit is not installed, reinstall the unit. 1. Position the machine against an object that will prevent the machine from moving. It is possible to drive through the brakes. 2. Raise the cab. Refer to the Operations and Maintenance Manual, "Cab Support Operation" for the correct procedure.
Illustration 19 g01356435 (1) Electrical connection (2) Brake solenoid 3. 4. 5. 6. Disconnect the electrical connection (1) for the brake solenoid (2). Sit in the operator's seat and fasten the seat belt. Lower the armrest. Start the engine. Run the engine at LOW IDLE and verify that the oil temperature is within the specification of 45 ± 5 C (113 ± 9 F). Slowly increase the engine speed to HIGH IDLE. Note: Do not stall the machine for more than 15 seconds. Damage to the machine could result. 7. 8. 9. Push the pilot operated hydraulic control in the FORWARD direction. At the same time, push the pilot operated hydraulic control ( work tool) to the TILT BACK position. Record the engine rpm. Model Table 12 Double Stall Engine 236B/ 246B/ 252B/ 262B 2300 ± 400 rpm If the engine stall RPM is not correct, refer to the troubleshooting section. Test and Adjust - Work Tool System
Escaping fluid under pressure, even a pinhole 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. Always use a board or cardboard when checking for a leak. 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 Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. NOTICE Do not adjust the main relief valve above the specified pressure. Adjustment of the main relief valve above the specified pressure may cause damage to the gear pump. Before any tests are performed, prepare the machine for troubleshooting. Refer to Testing and Adjusting, "Machine Preparation". Before any tests are performed, visually inspect the complete hydraulic system. Refer to the Testing and Adjusting, "Visual Inspection". Note: The hydraulic oil temperature during all system tests must be at an operating temperature of 45 ± 5 C (113 ± 9 F). Use the 164-3310 Infrared Thermometer or a equivalent to measure this temperature at the hydraulic filter. In order to increase the hydraulic system temperature, start the engine and operate all hydraulic cylinders for at least five cycles. Move the machine in the forward and reverse directions for several minutes.