DWP
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Pressure Unloading Valve, Size 10 Qmax = 60 l/min, pmax = 315 bar Two-stage, various on-off pressure differentials, optional soft-switching version Series DWPA…, DWPBU… S Compact construction for cavity type DD – M24 x 1,5 S Choice of 5 on-off differentials S 3 pressure ranges available S With integral pressure-relief function S Optional soft-switching model is available S All external parts zinc plated, chromited (CrVI-free) S Can be fitted in a line-mounting body Series DWPA… and DWPBU… cartridges are size 10, two stage, high performance pressure-unloading valves with an M24x1.5 mounting thread. They consist of a spool-type main stage and a leak-free, ball-type pilot stage. Unloading valves are used wherever a pump has to be disconnected from and re-connected to a pressure circuit. For this pur­ pose, either the 'Off' pressure or the 'On' pressure of the car­ tridge can be set. When the 'Off' pressure is set, the 'On' point will depend on the selected percentage on-off differen­ tial, or the other way round. To disconnect the pump, the cartridge responds to rising pressures at ports A and X by opening the connection from A → B. This connection is then kept open until the selected percentage on-off differential is reached (falling pressure at port X) and the connection A → B closes again (the 'On' point). The changeover to un­ loaded bypass can be made less harsh (soft switching) by using the DWPBU… model with damped switching charac­ teristics, which is available as an alternative. These unloa­ ding valves are predominantly used in accumulator-char­ ging circuits, 2-pump systems, and circuits for fast-advance → feed changeover, and in such cases the cartridges also provide a pressure-relief function e.g. for protecting the pump (see the application examples). All external parts of the cartridge are zinc plated and chromited (CrVI-free) and are thus suitable for use in the harshest operating environ­ ments. If you intend to manufacture your own cavities or are designing a line-mounting installation, please refer to the section “Related data sheets”. Technical data General characteristics Description, value, unit pressure unloading cartridge valve two-stage, with manual adjustment, various on-off pressure differentials, optional soft-switching version Mounting method Tightening torque Can be fitted in steel Can be fitted in aluminium nominal size 10, cavity type DD

General characteristics Description, value, unit Mounting attitude Ambient temperature range Hydraulic characteristics Description, value, unit Maximum operating pressure Maximum flow rate Nominal pressure ranges On-off differentials (on-off differential from 'Off' (unload) pressure) Flow direction Hydraulic fluid HL and HLP mineral oil to DIN 51 524; for other fluids, please consult BUCHER Hydraulic fluid temperature range Viscosity range Minimum fluid cleanliness Cleanliness class to ISO 4406 : 1999 ATTENTION! 1) Any back-pressure in port B (tank) directly redu­ ces the on-off pressure...

p = f (Q) Performance limits On-off differential 27 … 33 % / 37 … 43 % p [bar] 320 Dimensions & sectional view Standard model: DWPA… Model: DWPBU… (soft switching)

Installation information IMPORTANT! When fitting the cartridges, use the specified tightening torque. Set the switching point by means of the adjusting screw (s1). Either set the 'Off' pressure, in which case the 'On' pressure will depend on the selected percentage on-off differ­ ential, or the other way around. After you have set the valve, lock the adjusting screw with the lock nut. Seal ring Seal kit with FKM (Viton) seals, no. DS-230-V ATTENTION! Type DWPBU-2… (soft switching) pressure-un­ loading cartridges are not suitable for use in ap­ plications with 2-pump systems or circuits for...

Pressure-dependent fast-advance " feed changeover with 1 pump In this application, when the directional valve (WV) is in its parallel-arrows position, the unloading cartridge DWPA-2… remains closed until the valve pressure setting is reached, and oil discharging from the rod end of the cylinder is routed to the head end, where it supplements the pump delivery (fast-advance circuit). When the pressure at ports A and X rises above the setting, the unloading cartridge opens the connection A → B and the oil from the rod end flows to tank with virtually no back-pressure. This cancels the fast...

= pressure function 2 (internal pilot-oil drain to B, with external remote-control port X) = nominal size 10 = standard model - see relevant data sheets = special features - please consult BUCHER = soft switching, damped switching characteristics (optional) = two-stage unloading cartridge = pressure range 180…315 bar (Normal) = pressure range 80…210 bar (Medium) = pressure range 40…110 bar (Light) (blank) = NBR (Nitrile) seals (standard) V = FKM (Viton) seals (special seals - please consult BUCHER) On-off differential as % of Off (unload) pressure: 10 = 8…12 % (pressure ranges M and N only)...