HMB

Caterpillar excavator slewing mechanism composition and working principle

by:HMB     2021-01-25
( 2) Principle when manipulating excavator slewing, rotary pilot valve output pressure oil into the rotation directional valve 1 side of the valve core, promote rotary reversing valve valve core is moving, 1 open rotation directional valve 1 oil. The main pump output pressure oil through rotary reversing valve 1 into rotary motor oil ( A and B oil mouth) , drive rotary motor rotate 5. From rotary pilot valve pilot pressure oil into the delay of maximum 8 SH oil mouth at the same time, the SH pilot oil pressure to push oil at the mouth of the delay of the brake valve reversing valve valve core, make pilot pump output pressure oil ( PG oil mouth) Into the slewing brake 6 piston chamber. Add brake piston crown, the braking friction plate separation to remove brake, rotary motor 5 May 10 drive turntable rotate through the rotary gear reducer. When manipulating excavator stop turning, turning back to the median, pilot valve core pilot oil pressure relief, rotary reversing valve in the valve core to go back to one position, rotary motor oil (5 working A and B oil mouth) Is cut off, and the rotary motor 5 under the action of inertial continue to roll, rotary motor 5 oil return original lateral pressure, the high pressure oil as one of the main braking force of rotary motor 5 stop turning. Turning when the pressure reaches the pressure relief valve 3 set, rotary pressure relief valve 3 open, prevent high pressure rotary motor oil return side, protection work on slewing hydraulic system. Turning a pilot valve to return to, the remove of the slewing brake pilot pressure oil ( SH oil inlet pressure) Rapidly reduced to zero, the reversing valve 9 under the action of spring force movement to position as shown in figure 1, remove of the braking pressure oil through delay brake valve valve throttling orifice flow into rotary motor 5 shells, then flow back to the hydraulic tank. Brake spring stretch through the brake pistons on the implementation of brake lining. two Troubleshooting cases slewing mechanism malfunction phenomenon and the cause of each different, drivers and maintenance screen failure should be treated according to their characteristics respectively. 1 for 8850 h XE370C type hydraulic excavator, when to stop rotating, turntable scatter is obviously too, on the slope when stop, turntable automatically to the direction of rotation, turning process accompanied by sound. Screening delay brake valve analysis thinks, if the delay of maximum pressure reducing valve orifice plug, will lead to remove the forerunner of slewing brake oil flow back to the time of the motor shell extension; If the delay brake valve reversing valve is not completely reset, the forerunner of PG oil outlet pressure oil will only part of the oil flow to the rotary motor shell. Two kinds of conditions can cause brake piston is open, led to the turntable drift slewing brake is too large. Overhaul, clean delay brake valve pressure reducing valve and directional control valve, reinstall after commissioning, fault phenomenon remains. Screen rotation overflow valve and oil fill valve with two range for the 60 mpa pressure gauge, respectively, in the main pump ( P1, P2) pump Pressure mouth, insert the bucket bucket tooth surface, and then control excavator slewing, make the overflow of the rotary hydraulic systems, P1 pump pressure have been measured for 23. 8MPa( Normal at 27. 5MPa) , the pressure is low, the P2 pump pressure is 3. 5 mpa, the pressure is normal. This is because the rotary is by P1 pump oil alone, P2 main pump the oil in the pump output pressure relief valve to hydraulic tank. Although two rotary overflow valve and oil compensating valve failure probability is low at the same time, in order to quickly identify the fault parts, overhaul 2 fill oil check valve, replace two rotary overflow valve, fault has not ruled out still. Overhaul before disassemble rotary motor, rotary motor, first remove the oil return filter, found no abnormal metal powder and other dirt. Then disassemble rotary motor, check the plunger sliding boots, set plate, valve plate and cylinder, etc. There is no obvious wear. Check the brake piston, friction plate, brake spring without obvious damage phenomenon. When rotary motor spindle down, found that the main shaft of the roller bearing roller surface wear serious, has hemp dot, as shown in figure 2. Thus, slewing brake is the main reason of the turntable drift is too large when the rotary motor bearing excessive wear, rotary motor spindle and the installation position of the cylinder body causing displacement of valve plate and the cylinder with pressure force is reduced, rotary motor stops the original oil return a side to form high pressure, thus unable to form the required braking force. Roller bearing roller surface into a hemp dot, causing rotation to produce sound. We replaced the new bearing, clean all parts and components, motor and oil distribution plate and cylinder surface grinding, to clean and replace the new rotary reducer gear oil, reassemble the commissioning, after fault phenomenon disappeared.
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