BMC Training Presentation www BroadMachinery com Bulldozer Hydraulic

BMC Training Presentation www. Broad-Machinery. com

Bulldozer Hydraulic System BMC www. Broad-Machinery. com

CONTENTS BMC Ø Hydraulic System Principles Ø Hydraulic System Assembly Ø Malfunctions Analysis and Solving Ø Pressure Measurement to Diagnose hydraulic system www. Broad-Machinery. com

BMC Chapter One Hydraulic System Principles www. Broad-Machinery. com

Hydraulic System Principles BMC Hydraulic Components: Input: Pumps Output: Cylinders, Motors Controls: Valves Ancillary Equipment: Oil tank, Piping, Filters, Oil Cooler www. Broad-Machinery. com

Transmission & Steering Hydraulics BMC SD 22 & SD 32 Hydraulic System: Transmission and steering control systems are separated to each other, they draw oil from different pumps, but all the oil is from steering clutch case. The oil flows to the torque converter after transmission and steering, then the oil flows back to steering clutch case. So, the transmission and steering are one system called transmission & steering hydraulic system. www. Broad-Machinery. com

SD 22 Hydraulic System BMC www. Broad-Machinery. com

BMC Transmission & Steering Hydraulic System SD 16 Hydraulic System: Transmission and Steering control systems draw oil from Transmission case and Steering clutch Case. Oil flows to torque converter after transmission, then to transmission pan again through oil cooler. However steering clutch oil flows back to steering clutch case. So, the transmission and steering are two different systems. www. Broad-Machinery. com

SD 16 Transmission System BMC www. Broad-Machinery. com

BMC SD 16 Steering and Brake System www. Broad-Machinery. com

BMC Chapter Two Hydraulic System Assembly www. Broad-Machinery. com

Assembly & Operation BMC Gear Pump: Bulldozer Transmission & Steering Pumps are high pressure gear pumps. Their construction is simple and very efficient. Transmission Valve: SD 22, SD 32 have the same transmission valve unit. It is consists of Relief Valve, Return Valve, Pressure Reduction Valve, Speed Control Valve, Safety Valve and Direction Valve. Relief Valve & Return Valve are for transmission oil pressure, Speed Control Valve is for shift change, Direction Valve is for Forward and Reverse, Pressure Reduction Valve is for First Shift, Safety Valve is for protection of starting machine. www. Broad-Machinery. com

SD 22, SD 32 Transmission Valve BMC www. Broad-Machinery. com

BMC SD 16 transmission valve has no Safety valve, but other 5 valves’ structure and principle are same as SD 22 and SD 32. www. Broad-Machinery. com

BMC SD 16 Transmission Valve From Pump To Torque Converter www. Broad-Machinery. com

Modulating Relief Valve: BMC The modulating relief valve controls the buildup of oil pressure when the gear shift lever is operated and the clutch engaged, so as to avoid shock during start and off and improves the service life of power shift Modulating Time transmission. www. Broad-Machinery. com

Steering Valve BMC SD 32, SD 23, SD 22 and SD 16 steering valves’ structure and principle are the same. Steering & brake hydraulic system includes relief valve, steering control valve, brake booster valve. they have a bypass/relief valve, to avoid abnormal oil pressure if the filter is clogged. www. Broad-Machinery. com

BMC Steering Relief Valve Steering Valve www. Broad-Machinery. com

BMC Work equipment control system www. Broad-Machinery. com

BMC Relief Valve www. Broad-Machinery. com

BMC www. Broad-Machinery. com

BMC Chapter Three Troubleshooting & Problem Solving www. Broad-Machinery. com

Methods of Troubleshooting BMC Hydraulic system problems are caused by many factors. The Process of identifying a problem: Watch →Test Machine →Check Pressure Resolving the problem: a. Refer to Operation or Shop Manual b. Carry out adjustments/fit replacement parts www. Broad-Machinery. com

BMC Transmission Problems Solving www. Broad-Machinery. com

1. Gearshift inoperative Reason: BMC a. Inner Transmission Box: 1. the gearshift’s cylinder seal damaged or installed wrong 2. Oil path leak 3. if First Shift is inoperative: 1) Ball of anti return valve is broken 2) Oil path rotating seal ring is damaged b. Hydraulic system: 1. the 5 O-rings of clutch oil entrance in the seat of transmission valve are damaged 2. the factors of the pressure reduction valve: If the pressure reduction valve is blocked at closed position, 1 st gearshift is inoperative; if the pressure reduction valve piston hole is blocked, the oil pressure will increase, leading to worn seals, the 1 st gearshift is inoperative. www. Broad-Machinery. com

BMC 2. The machine drives on Neutral Gearshift Reason: 1. Incorrect adjustment of the direction valve position 2. Forward and reverse clutch disc distorted or broken, it locked, the clutch can’t separate completely. www. Broad-Machinery. com

3. The machine will not drive BMC Reason: The machine will not drive on any gearshift position, it’s because the clutch can’t get oil. 1. Transmission pump damaged, it can’t draw oil. 2. Transmission pump seal leak. 3. Transmission case oil level is down. 4. Oil piping leak, problem with pump. 5. Relief valve is blocked, 5 clutches have no oil pressure. www. Broad-Machinery. com

4. Gearshift Lag BMC Reason: 1. the clutch can’t get oil, suction piping leak. 2. Relief valve’s relief spring is broken, it delays the pressure increase in time. www. Broad-Machinery. com

5. Hot machine no drive, but cold machine is normal. BMC Reason: The suction pipe is aging or worn or distorted, and the suction ability is not good. The oil is thin, clutch can’t engage properly, so the hot machine has low power. www. Broad-Machinery. com

6. Transmission Torque Reduced BMC Reason: Relief valves blocked, the valve can’t move correctly, the oil pressure is low and the clutch can’t engage. www. Broad-Machinery. com

7. Torque converter over heating BMC Reason: a. Torque converter problem: 1. return oil pump filter is blocked 2. the seal leaking b. Hydraulic system problem: 1. oil quality is not good 2. oil quantity is low, or oil leak 3. insufficient cooling. www. Broad-Machinery. com

8. Steering filter cover bulged BMC Reason: Relief valves blocked or inlet blocked, the high pressure bulges the cover. Must clean the relief valve. www. Broad-Machinery. com

9. Poor Steering Control BMC Reason: Pulling the steering lever to the end and the pressure normal, the reason is that steering lever is adjusted incorrectly. www. Broad-Machinery. com

BMC 10. One side no steering, another side is normal Reason: 1. “S” tube o-ring is damaged 2. Clutch intake oil rotation seal is damaged 3. Clutch piston seal is damaged www. Broad-Machinery. com

11. Cold machine has steering, but hot machine has not steering BMC Reason: 1. The tube between steering pump and filter is damaged, so oil can’t pass through. 2. The oil becomes thin as the machine warms up, or the seal is worn, oil leak, oil pressure decrease. www. Broad-Machinery. com

BMC 12. Pulling one steering lever, the machine will stop Reason: This phenomenon shows that another side can’t transfer power, maybe another side steering direction valve block at open position. www. Broad-Machinery. com

BMC 13. Sometimes steering is intermittent Reason: Steering suction oil system seal is damaged and steering pump can’t get enough oil, the pressure is down. Due to steering pump drawing air, the oil filter has not oil, it leads transmission pump to draw air too. So sometimes transmission failure is caused by steering system damage. When the pump draws air, there are sharp whistle, and there are many air bubbles in oil. www. Broad-Machinery. com

14. Braking is poor BMC Reason: a. Brake band is worn out, need adjustment or replacement b. Brake linkage are adjusted incorrectly c. Brake booster valve don’t seal well www. Broad-Machinery. com

15. Pushing force is poor BMC Reason: a. Engine b. Torque Converter c. Transmission d. Steering Clutch www. Broad-Machinery. com

15. Pushing force is poor Check for the position of problem: BMC a. If the universal joint rotates, the malfunction is after engine or torque converter. b. If the universal joint does not rotate, then the malfunction is before transmission or steering clutch. c. If bevel gear rotates, the problem is at steering clutch; if bevel gear does not rotate, the problem is at transmission. www. Broad-Machinery. com

BMC 15. Pushing force is poor Check for the Pressure: a. If the pressure is right, it must be that there is mechanical malfunction or inner failure. b. If the pressure isn’t normal, we must diagnose, by referring to the manual. www. Broad-Machinery. com

BMC Chapter Four Pressure Measure for Diagnosis www. Broad-Machinery. com

Pressure Measurement to Diagnose hydraulic problems BMC 1. Important Measurements a. Oil brand, quality and grade are correct, steering case oil level correct b. Warm-up engine, ensure coolant and oil temperature are in 70 -90 o. C c. Engine is at operating speed 2. Measurement Method Measure the oil pressure at engine full speed and idle speed. 3. Measure Points, Standard Pressure (theoretic data in manual) www. Broad-Machinery. com

BMC Examples for Diagnosing Pressure Measurements www. Broad-Machinery. com

BMC 1. Machine will not move on selecting a gear Measure relief valve pressure: low is 0. 1, full speed is 0. 3 MPa. Due to this low pressure, gear clutch can’t get enough force, the machine can’t move. Discharge the air in steering filter, the pressure raised, but once engine stops 10 minutes later start again, the pressure is low again. This means that air is in the pump, replace the O-ring, and the problem is solved. www. Broad-Machinery. com

2. Speed is low in any gear BMC Measure transmission relief valve pressure: low is 0. 4 MPa, full speed is 0. 7 MPa Due to this low pressure, discharge the air from filter, it is not helpful. Then check the return valve, then find the valve piston is blocked, the oil is leaking from output. Clean the valve piston, reset it again, the problem is solved. www. Broad-Machinery. com

3. Power is down on the mid rpm BMC Measure transmission relief valve pressure: low is 1. 0 MPa, full speed is 3. 5 MPa, the pressure changed too much with increased engine speed, it means that the relief valve need to be adjusted. After checking, finding the valve piston is blocked with many carbon and corrupted hollows. After cleaning valve piston, reset it again, the problem is solved. www. Broad-Machinery. com

4. Torque converter power decrease BMC Measure transmission and steering relief valve pressure: both are normal. Measure the entrance of torque converter, the oil pressure is 0. 4 MPa Check torque converter safety valve, if spring is broken, replace it, the problem is solved. www. Broad-Machinery. com

BMC 5. If hydraulic oil temperature high, long term working, then the valve will block easily Measure transmission valve, the pressure is normal. Measure the entrance of torque converter, low speed pressure is 0. 1 MPa, full speed oil pressure is 0. 5 MPa. Due to the entrance pressure being low, the oil flow is low and cooling poor, so the temperature is high. Check torque converter, check the seal of inner oil path for damage, replace it, the problem is solved. www. Broad-Machinery. com

BMC 6. No steering at low speed, but at increased engine rpm, the steering is ok. Measure steering relief valve pressure: low speed pressure is 0. 4 MPa, full speed oil pressure is 1. 1 MPa; And steering clutch oil pressure is low. At the same time the valve is faulty. It means that steering relief valve is the problem, check it, if the spring is broken, replace it, the problem is solved. www. Broad-Machinery. com

BMC 7. Cold machine steering is normal, but after working, the steering is very heavy Measure steering relief valve pressure: low speed oil pressure is 0. 5 MPa, full speed oil pressure is 1. 1 MPa; Steering relief valve oil pressure is low, it is caused by a blockage of relief valve. Disassemble and clean it, the problem is solved. www. Broad-Machinery. com

BMC 8. One side steering is not serviceable Steering relief valve pressure is normal, other side steering brake pressure is normal too, but this side steering brake pressure is low. It show this booster or its piping has a leak. Disassemble booster, check the piping entrance o-ring is damaged, replaced it, the problem is solved. www. Broad-Machinery. com

BMC The End of This Training Module Thanks Your Cooperation !!! www. Broad-Machinery. com