Variable Displacement Pump A4VG - Group VH A/S

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12/52 Bosch Rexroth AG | Mobile Hydraulics A4VG | RE 92 003/05.03DA - Hydraulic Control, Speed RelatedThe DA control is an engine speed-dependent, or automotive,type control system. The built-in DA regulating cartridgegenerates a pilot pressure that is proportional to pump (engine)drive speed. This pilot pressure is directed to the positioningcylinder of the pump by a solenoid actuated 4/3 way directionalvalve. Pump displacement is infinitely variable in each directionof flow, and is influenced by both pump drive speed anddischarge pressure. Flow direction (i.e. machine forward orreverse) is controlled by energizing solenoid a or b.Increasing pump drive speed generates a higher pilot pressurefrom the DA cartridge, with a subsequent increase in pumpflow and/or pressure.Dependent on the selected pump operating characteristics,increasing system pressure (i.e. machine load) causes thepump to swivel back towards a smaller displacement. Engineoverload (anti-stall) protection is achieved by the combinationof this pressure-related pump de-stroking, and the reduction ofpilot pressure as the engine speed droops.Any additional power requirement, such as implementhydraulics, may result in further engine pull down. This causesa further reduction in pilot pressure and therefore pumpdisplacement. Automatic power division and full utilization ofavailable power is thus achived for both the vehicletransmission and the implement hydraulics, with priority givento the implement hydraulics.To provide controllable reduced vehicle speed operation whenhigh engine speeds are required for fast implement hydraulics,various inching options are available.The DA regulating cartridge can also be used in pumps withconventional control devices, such as EP, HW or HD, toprovide an engine anti-stall function, or as a combination ofautomotive and displacement control functions.Application of the DA control is only appropriate on certaintypes of vehicle drive systems, and requires a review of theengine and vehicle parameters to ensure proper application ofthe pump, and safe and efficient machine operation. All DAapplications must therefore be reviewed by a RexrothApplication Engineer.Hydraulic control, speed related,DA-control valve, fixed setting, DA1D2/DA2D2 1 )) size 28 and 250 without port F a1 and F S GraphDirection of rotation – Control – Direction of through put flowSize Solenoid Control Through put Operatingpressure flow pressurea X 2B to A M A28...56b X 1A to B M Ba X 2A to B M B71...250b X 1B to A M Aa X 2A to B M B28...56b X 1B to A M Aa X 2B to A M A71...250b X 1A to B M BSizes 28, 250 Sizes 40...180BM B(size 250)BM BAM AM A (size 250)Aswitching solenoid aView ZX Zswitching solenoid a1M A (size 28)anticlockwiseXanticlockwise1BclockwiseclockwiseX 2 M B (size 250) M B (size 28)X 2switching solenoid bswitching solenoid bTechnical data - solenoidsDA1DA2Voltage 12 V (±20 %) 24 V (±20 %)Zero position V g 0 solenoid solenoidde-energized de-energizedPosition V g max solenoid solenoidenergized energizedNominal resistance (at 20°C) 5,5 Ω 21,7 ΩNominal power 26,2 W 26,5 WCurrent required, minimum effective 1,32 A 0,67 ADuty cycle 100 % 100 %Insulation class see connector design, page 48Standard: Switching solenoid without manual emergencyoperation. Manual emergency operation with resetby valve spring on demand.Direction of rotationanti-clockwise clockwise
RE 92 003/05.03 | A4VG Mobile Hydraulics | Bosch Rexroth AG 13/52Function and Control of DA ValvesDA control valve, fixed setting, (2)Control pressure is generated in relation to drive speed. Whenordering, please state in clear text: Start of control (set atfactory).DA control valve, mechanically adjustable with control lever (3)Control pressure is generated in relation to drive speed. Whenordering, please state in clear text: Start of control (set atfactory).Control pressure may be reduced (independently of drivespeed) as required by operation of the control lever (inchfunction).Max. adm. operating torque at the control lever __ T max = 4 NmMax. angle of lever operation 70°. The position of the lever isoptional.Variation 3L ____ operation direction of the control lever anti-clockwiseVariation 3R _______ operation direction of the control lever clockwiseCircuit diagrams 1 ):Hydraulic control, speed related,DA control valve, mech. adjustable with control lever DA1D3/DA2D3Hydraulic control, speed related,DA control valve, fixed setting,with hydraulic inch valve, DA1D4/DA2D4with throttle valve,sizes 28...71Hydraulic inch valve, (4, 5, 8, 9)(only for pumps with DA control device)– for inch function; for use in conjunction with DA controlvalve, fixed setting (4, 8) or mechanically adjustable (5, 9)Model with throttle valve sizes 28, 40, 56, 71Model with pressure reducing valve sizes 90, 125, 180, 250Permits the control pressure to be reduced independently ofthe drive speed via hydraulic control (port Z).Variation 4, 5:The control at port Z by means of brake fluid from the vehiclebraking system (hydraulically linked with the service brake).Variation 8, 9:The control at port Z by means of mineral oil.with pressure reducing valve,sizes 90...250Master controller as inch valve, (7)– for inch function; for use in conjuction with DA control valve,fixed settingAny reduction of control pressure, independent from the inputspeed through the mechanical operation of the mastercontroller.The master controller is installed separately from the pump (forinstance in the driver’s cabin) connected with the pump by 2hydraulic control lines at ports P S and Y.A suitable master controller needs to be ordered separatelyand is not included in delivery volume.Hydraulic control, speed related, DADA control valve, fixed setting, with separately installed mastercontroller as inch valve, DA1D7/DA2D7master controller(is not included in delivery volume)Extensive information is available from our mobile salesdepartment. Please make use of an opportunity to confirm yourtransmission design through our computer programme. A DAcontrol can only be approved by Rexroth.Note: rotary inch valve see page 49.1 ) size 28 and 250 without port F a1 and F S
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Variable Displacement Pump A4VG - Group VH A/S

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