Variable Displacement Pump A4VG - Group VH A/S

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8/52 Bosch Rexroth AG | Mobile Hydraulics <strong>A4VG</strong> | RE 92 003/05.03High Pressure Relief ValveSetting diagramp max≥ 30 baroperating pressure pA, Bat ports A, Bsafety margin∆p drive designpressurepSpboost press.q v1set valuepressure cut-offp Spq v maxdifferential pressure ∆pHDhigh press. (HD) valve settingSetting rangeHigh pressure relief valve, Differential pressurepilot controlled (sizes 71...250) setting ∆p HDSetting range valve 1420 bar∆p 100 - 420 bar 400 bar 1 )(see ordering code)360 bar340 bar320 bar300 bar270 bar250 bar230 bar200 bar150 bar100 bar1 ) Standard valve setting of differential pressure, if not specified.Note: valve setting is done atn = 1000 rpm und V g max (q V 1V 1 )Example: boost pressure 30 bar; operating pressure 400 baroperating pres. p A,B – boost pres. p Sp + safety margin =differential pres. ∆p HD400 bar – 30 bar + 30 bar = 400 barHigh pressure relief valve, Differential pressuredirect controlled (sizes 28...56) setting ∆p HDSetting range valve 3, 5 420 bar∆p 270 - 420 bar 400 bar 1 )(see ordering code)360 bar340 bar320 bar300 bar270 barSetting range valve 4, 6 250 bar∆p 100 - 250 bar 230 bar 1 )(see ordering code)200 bar150 bar100 barBypass functionSizes 28...56: HD valves direct controlled (3), (4): without bypassSizes 28...56: HD valves direct controlled (5), (6): with bypassSizes 71...250:HD valves pilot controlled (1): with bypassSimplification:The bypass function is not shown in the circuitdiagramsThe pilot controlled HD-valves (sizes 71..250)are not shown in the circuit diagrams.Pressure Cut-Off, DThe pressure cut-off corresponds to a pressure regulation which, afterreaching the set pressure, adjusts the pump volume of the pump toV g 0 = 0.This valve prevents the operation of the high pressure relief valveswhen accelerating or decelerating.Both the pressure peaks occurring when the swashplate is swivelledrapidly and also the maximum pressure in the system are safeguardedby the high pressure relief valves.The setting range of the pressure cut-off may be anywhere within theentire working pressure range. However, it must be set 30 bar lowerthan the setting of the high pressure safety relief valves (see settingdiagram).Please state the setting value of the pressure cut-off in clear text whenordering.Please state in clear text when ordering:(only the values ∆p HD shown in the table are possible)High pressure relief valve ADifferential pressure setting: ∆p HD = ... barOpening pressure of the HD-valve (at q V 1 ): p max = ... bar(p max = ∆p HD + p Sp )High pressure relief valve BDifferential pressure setting: ∆p HD = ... barOpening pressure of the HD-valve (at q V 1 ): p max = ... bar(p max = ∆p HD + p Sp )Example for pressure cut-off:Electrical two-position control, EZ1D/EZ2D
RE 92 003/05.03 | <strong>A4VG</strong> Mobile Hydraulics | Bosch Rexroth AG 9/52HD1 - Hydraulic Control, Pilot Pressure RelatedThe positioning cylinder of the pump and therefore the swivelangle is varied in proportion to the difference in pilot pressureapplied to the two control ports (Y 1 and Y 2 ). The pumpdisplacement is therefore infinitely variable. One pilot line isassigned to each direction of flow.GraphDirection of rotation – Control – Direction of through put flowSize Pilot Control Through put Operatingpressure pressure flow pressure– Vg1,00,80,60,4p St in bar181614121086420,200 0,2 0,4 0,6 0,8 1,024681012141618– pSt in barV gV g maxDirection of rotationanti-clockwise clockwise28...5671...25028...5671...250Y 1X 1A to B M BY 2X 2B to A M AY 1X 1B to A M AY 2X 2A to B M BY 1X 1B to A M AY 2X 2A to B M BY 1X 1A to B M BY 2X 2B to A M ASizes 28, 250 Sizes 40...180BM B (size 250)BM BV gV g maxdisplacement at p Stdisplacement at p St= 18 barAM A (size 250)AM AV g maxModel with DA control valve 1 )Pilot pressure p St = 6 - 18 bar (at ports Y 1 , Y 2 )Start of control 6 barEnd of control 18 bar (max. displacement V g max )An optional DA control valve allows automotive drive control ofthe vehicle see, page 13.For pressure cut-off, see page 8.clockwiseX 2X 1ZanticlockwiseView ZM A (size 28)anticlockwiseclockwiseM B (size 250) M B (size 28)X 1X 2Y 1Y 2BStandard model 1 )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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