MHV - Manual operation
28Pages

Publ. MHV...K-E-06/07 MHV PROPORTIONAL DIRECTIONAL CONTROL VALVE Manual operation Sizes 12, 16, 20, 25, 32 Series MHV...K FEATURES * The load independent output flow is proportional to the input signal (lever position). * The pump pressure always corresponds to the user pressure, +3,6,8 or 12 bar (43, 86, 114 or 172 psi) Dp compensator. * The built-in pump-unloading valve results in: - very low power turned into heat; - minimum loading of the prime mover. * User speed is precisely controlled under all load conditions. * Progressive regulating curve; no pressure peaks when switching; sensitive control even for alternating pressures. * Constant working speed of differential cylinders at the different regulating flow to the valve by grinding angle. * Constant recirculation pressure independent of the number of units. * Any limiting of flow for every user port. * Proportional directional control valves also available as: · Hydraulic proportional series MOV and · Electrical proportional series MEV. Any combination of these control options is possible. * The sandwich system allows a construction up to 8 control valves. * Electrical pressure cut off at port A, B or A and B, available on request.

2 Operating pressure (P,A,B) ...350 bar (5000 psi) Maximum return pressure (T): - aluminium endcaps 15 bar (214 psi) - cast iron endcaps 30 bar (428 psi) Dp compensator 3; 6; 8 or 12 bar (43; 86; 114 or 172 psi) Pressure setting range 5...350 bar (72...5000 psi) Flow range ...800 l/min (...211 USgpm)- with 32 cSt at 40°C Fluid Mineral oil according to DIN 51524/51525 Fluid temperature range -35...+80°C (-31°...+176°F) Viscosity range 2,8...380 cSt, optimal 30 cSt Contamination level max. according to NAS 1638 Class 9 or ISO 18/15 Mounting position optional Lever, std. Stainless steel Size...

3 DESCRIPTION Conventional directional control valves control start, stop and directions of movement from hydraulic motors and cylinders. However, the speed of these users depends on the load pressure. If this load pressure varies, the speed is hardly controllable (figure 1) The AMCA proportional directional control valves are pressure compensated and achieve an ideal control of force, speed, acceleration and deceleration, independent of the load and increased demands (figure 2) The pressure compensator could be a pressure relief valve (MUV) or a pressure reducing valve (MDM), together with...

4 Functioning of the by-pass (3-way) flow control valve (with MUV) (this type is used in combination with fixed displacement pumps) (fig. 7 and 8) The AMCA-MUV has three functions: 1. Energy saving If the directional control spools are in neutral position (spool 1 in fig.7), and the pump is running, the pressure relief valve 1 (MUV) opens at low pressure (depending on the spring 3, 6, 8 or 12 bar (43, 86, 114 or 172 psi)). P and T are connected. The power (pxqv) turned into heat is very low. The spring chamber is connected, via the “loadpressure check back system”, to T (tank). (example...

5 OPERATION another circuit Spool 2 B2 End plate A2 MDM orifice Pressure relief valve 1 (MUV) Pressure relief valve 1 (MUV/R) Reducing valve (MDM) 0 M Inlet plate Spring chamber B1 T P A1 spool orifice T1 End plate Load-pressure check back system Adjustable relief valve 2 Spool 1 Damping-screw B2 B1 A2 A1 spool orifice R another circuit P Spring chamber Inlet plate Damping-screw Load-pressure check back system Spool 2 Spool 1 Adjustable relief valve 2 Adjustable relief valve 2 Load-pressure check back system T1 B2 B1 End plate A2 A1 P Spring chamber Inlet plate Spool 2 Spool 1 Damping-screw...

6 Functioning of the proportional directional control valve with lever control (see fig. 13 and 14) - The handle mechanism and the return springchamber of the directional control spool are both provided with the used hydraulic fluid. This gives a perfect lubrication on the ball (fig.13) or rack and pinion (fig. 14) construction for fine control of the handle mechanism. - The return pressure acts on both sides of the directional control spool. For every valve both chambers at both sides of the spool are connected to each other and connected to T by an orifice, this prevents spool movements...

12 T P MUV MHV A B AP MDM MHV A B AP/T P T1 3: AP-12-K 1: MUV-12-K 2: MHV-12-KSFWA-30/30 B A P T 2 A B P T A P T B 3 1 TYPE OF VALVE MOUNTING The AMCA proportional directional control valves series MHV...K are ganged valves. A complete AMCA-MHV..K system consist for example of three main parts (fig 16). 1. MUV or MDM : pressure relief (MUV, fig 17) or pressure reducing (MDM, fig 18) valve 2. MHV .. : 4/3 directional control valve with lever control. 3. AP : endplate. CONFIGURATION Fig. 16 Fig. 17 Fig. 17A Fig. 18 Fig. 18A

13 The following options are possible (see fig 19, application (example) and ordering code). Port connections: T1 : Low back pressure. - if there are cylinders in the circuit with a large returnflow, T1 shall be connected to tank for a lower return pressure in the valve; - if a MDM-valve is mounted, T1 is the mainport to tank std. mounted on the endplate; - if a MUV-valve is mounted, the T1 on the endplate is an option. X : Auxiliary port (on the MUV or MDM valve) - the maximum pressure-level in the entire system can be remotely controlled by the use of a small relief valve (size 4 mm (0.16...

14 VARIANTS / OPTIONS Compensator (MUV/MDM) variants: Adjustment 3 up to 12 bar (43...172 psi).Fig 20. V : The spring in the spring chamber is adjustable between 3 and 12 bar (43 and 172 psi) for decreasing or increasing the max. flow at user A and B of the proportional control valve. This variant is recommended at a constant pressure circuit in combination with a very low load-pressure. Position lock: F : Standard, spring return to center position. B : Friction brake with center detent, fig 21, the spool can be set in any position. O : No spring return to center position R : Detent, fig...

15 APPLICATIONS Fig. 23 Hydraulic foundation rig