` JSI - EN - 05-2E - 002 Date Feb 1st, 2005 Total Pages 6 P re se n t P a g e 1 Boom load holding valve The boom pump sucks hyd. oil from the reservoir and supplies oil to each boom cylinder through the boom control valve which gives the direction of the oil flow proportionally. The boom cylinder is extended when the oil is supplied to the piston-side load holding valve, and contracted when supplied to the rod-side. In case of Z-boom, it works in the reverse direction. Major features of load holding valve(hawe) Boom load holding valve prevents pulling or pushing from accelerating uncontrollably during movements in load direction or from proceeding with higher speed than intended. This is accomplished by throttling of the return flow from the boom cylinder. The load holding valve generates a flow resistance, which is always a little bit higher than the pressure created from the load. This back pressure is only generated under negative load conditions. The throttle device is self-adjusting and therefore adapts continuously to any alternation of the load condition. This is achieved by an equilibrium of forces between the outflow and inflow acting on the functional valve elements on the one side, and the valve spring acting on the other side. Each hyd. line on LHDV F LINE : V/V의 F는 CHECK 기능을하고, 유압유가들어가기도하고나오기도한다. Z LINE : 반대쪽 CHECK V/V 의유로를열어줌. HEAD의 Z는 ROD의 S LINE과연결되어 ROD의 V에서나오는유압유를 F를통하게하여 BOOM CONTROL V/V 쪽으로들어가게한다. ROD의 Z는 HEAD의 S LINE 과연결되어 HEAD의 V에서나오는유압유를 F를통하게하여 BOOM CONTROL V/V 쪽으로들어가게한다.
Total Pages 6 P re se n t P a g e 2 S LINE : Z LINE과연결되어닫혀있던 RELIEF에 PILOT LINE으로 V/V를열어유압유가흐를수있게한다. M LINE : GAUGE POLT LINE으로실린더에걸리는압력확인할때사용하며, 막음볼트를제거하고게이지포트를설치하여게이지를장착하고 BOOM 을움직이면서압력치를확인한다. R LINE : V/V의 R은 RELIEF 기능을하고, TANK 로연결되어드레인된다. 각부분회로도 13MM M M36 이상 CHECK V/V 유압회로도 BOOM CONTROL V/V 30MM 27MM F F 22MM 19MM V R R 17MM S Z 17MM 27MM 22MM 24MM TANK S Z V M R R S TANK S Z Z F F
Total Pages 6 P re se n t P a g e 3 각부분전개도
Total Pages 6 P re se n t P a g e 4 LHDV 밸브의각부기능 1 Throttling 구멍이있는 valve piston 과 valve sheet : 작동유의통과유량에따라 5 종류가있으며, 유로가개폐될때 Throttling 효과로부드러운전환이가능하다. 2 3 4 5 6 7 부하를유지하는압력을 Setting하는스프링 : 예상되는부하압력보다최소한 10% 높게설정한다. 판형 Check valve : valve로들어가는이물질을걸러주는 strainer 가있다. 면접촉이므로이물질에약해실린더의처짐의원인이될수있다. Pilot piston : 외부Pilot압력에의해 valve 를개폐한다. 내부 Pilot와의단면적비는 8.9:1 또는 11.1:1 이다. D1 Orifice :PilotLine입구측에있고이물질을막기위해필터가설치되어있고표준타입은 0.5mm 이며, D2 Orifice와함께들어오는 Pilot oil을 Damping 한다. D2 Orifice : Pilot oil을 Drain 시킴으로 Pilot piston에작용하는작동압을제어 한다. 표준타입은 0.5mm이고 0.4 ~ 0.8 까지여러가지타입이있고, D2 Orifice의사이즈에따라 Pilot 단면적비가변화한다. 작동성은 D2가클수록부드러워지고 bouncing 이짧아지고, D2가작을수록 딱딱해지고 bouncing 이길어지는경향이있다. Check valve : Damping 기구의한구성품으로 Pilot piston으로들어가는 oil 은자유롭게, 빠지는 oil은막아서 Damping Throttle 을통해빠지게한다.
Total Pages 6 P re se n t P a g e 5 8 Damping Throttle : Pilot piston에작용한오일이빠질때그흐름을제한해서제어압력이서서히떨어지게한다. 이 Throttle을조이면정지동작이부드러워지나응답성이떨어지고, 풀면반대로딱딱해지고응답성이좋아진다. 9 Pre-load valve : 20bar로 Setting 되어있으며, 20bar 이상에서는빠른응답성을그이하에서는일반Dampin g 특성을나타냄으로써부드러운작동성을동시에얻을수있다. 10 Shock valve : Actuator에발생되는쇼크압을제거해주는 Relief valve 이다. setting 압력은 counter balance압력보다약 20bar 높게설정한다. 최대부하제한용으로사용되거나, Actuator 가 Motor 일경우브레이크밸브로사용될수있다. 11 압력조정나사 : 압력조정및풀림방지
Total Pages 6 P re se n t P a g e 6 LHDV 밸브의특성 위그림의그래프선도에서보는바와같이붐체크밸브의초기작동시에는큰폭의유량변화가존재하여붐이흔들리는현상이발생하는것은당연한유압적인결과이다.
Total Pages 2 P re se n t P a g e 1 Subject Specification of load holding valve Load holding valve (Till March 2004) Model 1st 2nd 3rd 4th 5th Piston Side Rod Side Piston Side Rod Side Piston Side Rod Side Piston Side Rod Side Piston Side Rod Side M33 370 370 370 370 370 370 370 370 Part # RB65335 M36 330 210 330 330 330 330 210 330 Part # RB115 RB335 RB331 RB332 RB331 RB487 RB335 RB332 8-330 / 350(D1=0.6) -210 / 230-330 / 350-330 / 350-330 / 350-370 / 400-210 / 230-330 / 350 M40 370 270 330 270 330 330 230 270 Part # RB876 RB444 RB557 RB444 RB331 RB557 RB551 RB445 LHDV33H-15N8-370 / 390-330 / 350-330 / 350-330 / 350-230 / 250 M42 300 310 330 350 300 350 250 295 Part # RB555 RB556 RB557 RB442 RB558 RB559 RB562 RB552 LHDV33H-15C7-300 / 320-310 / 330-330 / 350-350 / 375-300 / 320-350 / 370-250 / 270-295 / 320 M43 350 210 350 330 330 270 270 270 Part # RB443 RB335 RB442 RB332 RB331 RB445 RB444 RB445 8-350 / 375(D1=0.6) -210 / 230-350 / 375-330 / 350-330 / 350 M48 330 270 370 270 350 270 370 295 230 270 Part # RB484 RB598 RB485 RB444 RB486 RB445 RB487 RB552 RB551 RB445 LHDV33H-15B7-330 / 350 LHDV33H-15N6-370 / 380 LHDV33H-15P6-350 / 380-370 / 400-295 / 320-230 / 250 M50 330 270 370 270 350 270 370 370 230 400 Part # RB484 RB598 RB485 RB444 RB486 RB445 RB487 RB487 RB551 RB860 LHDV33H-15B7-330 / 350 LHDV33H-15N6-370 / 380 LHDV33H-15P6-350 / 380-370 / 400-370 / 400-230 / 250 LHT21H-14-A4-400 M55 360 210 340 370 340 350 350 420 370 400 Part # RB840 RB841 RB842 RB485 RB842 RB843 RB486 RB853 RB487 RB860 LHDV33H-15M6-360 / 380 LHDV33H-15B6-210 / 230 LHDV33H-15B6-340 / 360 LHDV33H-15N6-370 / 380 LHDV33H-15B6-340 / 360-350 / 370 LHDV33H-15P6-350 / 380-420 / 440-370 / 400 LHT21H-14-A4-400
Total Pages 2 P re se n t P a g e 2 Subject Specification of load holding valve Load holding valve (From March 2004) Model Setpart# Component of set Qt'y Part # Qt'y 1P ALL 5R M33 ST044 MS048 ORIFICE-D1=0.5, D2=0.6 7 7 MS041 ORIFICE-D1=0.5, D2=0.7 1 1 X33 MS026 LHDV33H-11D6-350 8 8 M37 MS049 LHDV33H-15M6-380/400 7 7 Z37 ST050 M40 MS084 LHDV33H-15M7-380/400 1 1 M42 M43 ST051 MS049 LHDV33H-15M6-380/400 7 7 MS082 LHDV33H-15M8-380/400 1 1 M50 MS049 LHDV33H-15M6-380/400 8 8 Z50 ST070 MS084 LHDV33H-15M7-380/400 1 1 M55 RB860 LHT21H-14-A4-400 1 1 Remark Orifice of LHDV Part # Description Orifice spec. Setting Pressure Fline Rline MS048 OVER CENTER VALVE D1=0.5, D2=0.6 MS041 OVER CENTER VALVE D1=0.5, D2=0.7 MS049 LOAD HOLDING VALVE D1=0.6, D2=0.6 380BAR 400BAR MA082 LOAD HOLDING VALVE D1=0.6, D2=0.8 MS084 LOAD HOLDING VALVE D1=0.6, D2=0.7 RB086 LOAD HOLDING VALVE D1=0.6, D2=0.4 400BAR Caution 1 : MS049 can be used for old type LHDV. Caution 2 : In case of piston side of 1st cylinder, MS082 or MS 084 have to be used. Caution 3 : RB860 LHT is only for Z50/M55, rod side of 5th cylinder.