Remote Hydraulic Pilot Operated Directional Control Valve WEH 10 16 25 32 Manual

4/3, 4/2 and 3/2 directional valves of pilot operated

Type WEH 10, 16, 25 and 32

Features

– Valves used to control the start, stop and direction of a fluid flow

– Electro-hydraulic operation (WEH)

– Porting pattern conforms to DIN 24 340 form A,ISO 4401 and CETOP-RP 121 H

– Wet pin DC or AC solenoids, optional

– Hand override, optional

– Electrical connections as an individual or central connection

– Spring or pressure centered, spring or hydraulic offset.

Function and configurations

Valves of type WEH are directional spool valves with electro-hydraulic operation. They control the start, stop and direction of a flow.

Solenoid valves used for pilot control are with wet AC or DC solenoid available; Main valves apply spring centering and spring reset or hydraulic centering and hydraulic reset; with or without Switching time adapters; with or without stroke regulators for main valves; back pressure valves may be installed in main valves; throttle may be installed; pressure reducing valves may be installed when working pressure exceeds 250bar.

The valve mainly consists of main valve body(1), main valve spool(2), one(or two)reset spring (3) with one(or two) pilot solenoid valve of solenoid. Main valve spools (2) is held in the neutral or in the initial position either by the springs or by means or pressure. Pilot solenoid valves (4) may select wet-type AC or

DC solenoids (5) and pilot solenoid valves are able to control the switching of main valves.

There are four patterns on supply and drain of control oil, see the function diagram.

Following are descriptions of various types of valves:

1. Main valves are 4/3-way directional valve with spring centering of the control spool.

Main valve spool (2) is held in the neutral position by means of two return springs. And two spring chambers (6) are connected with tank through pilot solenoid valves.

When one of the two ends of the main control spool (2) is pressurized with pilot pressure, the spool is moved to the switched position. The required ports in the valve are then opened to flow.

When the pilot pressure is removed, the spring on the opposite side to the pressurized spool area causes the spool to return to its neutral or initial position.

                 Structure chart of spring centering electro-hydraulic directional valve

1- Main valve body

2- Main valve spool

3- Reset spring

4- Pilot solenoid valve

5- Solenoid

6- Spring chamber

7- Control oil inlet passage

8-Manual button

2. Main valves are 4/3-way directional valve with pressure centering of the main control spool, type 4WEH...H

The main control spool (2) in the main valve is held in the neutral position by pressurization of the two end faces. A centering sleeve (9) is supported in the housing and holds the spool in position.

By removing the pressure from one of the spool ends, the main control spool (2) is moved to the shifted position.

The unloaded spool area displaces the returning pilot oil via the pilot valve into the tank (external connection).

            Structure chart of electro-hydraulic directional valves of hydraulic pressure centering

1- Main valve body

2- Main valve spool

3- Spring

4- Pilot solenoid valve

5- Solenoid

6- Spring chamber

7- Control oil inlet passage

8- Manual button

9- Centering sleeve

2/4 way directional valves

( this kind of valve has four different structures and Types)

1. Type WEH.../...

This kind of pilot valve and main valve have a reset spring each, resetting by spring force.

2. Type WEH...H.../...

This kind of valve has a reset spring, making pilot valve spool stay in initial position. Main valve spools change directions under effect of pressure oil.

3. Type WEH...H.../O...

This kind of valve has two solenoids. There are no reset springs in pilot valves and main valves, thus using solenoids and pressure oil to make pilot valves and main valve spools change directions. Therefore, at least one solenoid shall be under working sate.

4. Type WEH...H.../OF...

This kind of valve has two solenoids and locators which makes pilot valve spools stay in working position (impulse valves). Main valve spools have no locating devices, moving downward to corresponding working positions under effect of pressure oil.

Structure 2, 3 and 4 aforesaid are hydraulic reset. Main valve spools can stay in the working position only under the effect of pressure oil.

Throttle insert:

The use of a throttle insert is required if the pilot oil supply in the P channel of the pilot valve is to be limited. This throttle is inserted in the P channel of the pilot valve.

Pilot oil supply:

1. Type WEH10

(1) Conversion between internal supply and external supply:

P channel on the top of main valve bodies with M6 bolt (2) is external supply and with M6 bolt (2) dismounted is internal supply.

(2) Conversion between internal drain and external drain:

Dismounting plug screws (1) and installing M6 bolt (2) is external drain; dismounting M6 bolt(2) is internal drain.

2. Type WEH16

(1)Conversion between internal supply and external supply:

Dismounting plug screw (10) form P channel on the side surface of main valves and installing M6 bolt (9) is internal supply. Dismounting M6 plug bolt (9) is internal supply.

(2)Conversion between internal drain and external drain:

Dismounting plug screw (10) form T hole on the top of main valves and installing M6 plug bolt (9) is internal drain. Dismounting M6 bolt (9) is external drain.

3. Type WEH25

(1)Conversion between internal supply and external supply:

P channel on the top of main valve bodies with M6 bolt (6) is external supply and with M6 bolt (6) dismounted is internal supply.

(2)Conversion between internal drain and external drain:

Dismounting plug bolt (6) form T hole on the top of main valves and installing M6 plug bolt (9) is internal drain. Dismounting M6 bolt (9) is external drain.

4. Type WEH32

(1)Conversion between internal supply and external supply:

Dismounting plug screw (9) form P hole on the undersurface of main valves and installing M6 bolt (9) is internal supply. Dismounting M6 plug bolt (9) id internal supply.

(2)Conversion between internal drain and external drain:

Dismounting plug screw (9) form T hole on the top of main valves and installing M6 plug bolt (9) is internal drain. Dismounting M6 bolt (9) is external drain.

Attention:

X port on base plates must be blocked when internal supply occurs and Y port on base plates must be blocked when internal drain occurs.

Switching time adjustment:

In order to influence the switching time of the main valve a double throttle check valve has to be fitted between pilot valves and main valves to control oil supply from pilot valves into main valve spools, thus adjusting the switching time of main valves.

Regulating bolt rotation clockwise, the time for switching of main valves is long, otherwise the time is short.

The throttle check valve has two kinds: meter-in throttling and meter-out throttling. If there is a need of changing meter-in throttling into meter-out throttling, just install the valve after rotating 180^.around the longitudinal axis again and then install pilot valves.

1- Main valve

4- Pilot valve

11- Switching time regulator (Z2FS6)

12- Meter-out throttling

13- Meter-in throttling

14- Adjustable bolt

15- Seal ring support plate

16- Set screw M5×L GB/T70.1-10.9 grade, the length of L is determined by height stacked, tightening torque 8.9 Nm.

Pressure reducing valves:

The pressure reducing valve (8) must be used it the pilot pressure is higher than 250 bar (for type 4WEH 22 ...: 210 bar).Pressure reducing ratio of constant-ratio pressure reducing valves (D1)1:0.66.

Pressure reducing pressure of constant-ratio pressure reducing valves shall not exceed 40bar.

Minimum control pressure of technical specifications shall improve 1/0.66=1.515 after installing bottom plate pressure reducing valves.

Constant-ratio pressure reducing valves shall not be used when controlling internal oil drain and using back pressure valves (P0.45) with control pressure decreased to 3bar.

1- Main valve

4- Pilot valve

11- Switching time regulator

17- Pressure reducing valve

18- Bolt M5×L GB/T70.1-10.9

Back pressure valve:

Valves controlling oil inner supply with unloading passages, such as C, Z, G, H, P, S, T and V, in valves with zero pressure circulation and internal pilot oil supply, a back pressure valve (9) must be installed in the P-channel of the main valve to build up the minimum pilot pressure. The pressure differential of the back pressure valve must be added to the pressure differential of the main valve (see characteristic curves) in order to determine the actual value. The opening pressure of this valve is approx. 4.5 bar. NG10 valves do not have back pressure valves.

19- Back pressure valve

20- Main valve

21- Control oil chamber(X)

22- Connecting plate

Specifications

Note:

1. For function of WEH10 such as C,Z,F,G,H,P,T,V , etc., if applying control oil internal sup, please try to use external add enough back pressure on return port T( port Y shall not have back pressure) to ensure valves can reverse properly.
2. Pressure reducing valves shall be applied when control pressure exceeds 250bar.

Note:

1. For function of WEH16-32 such as C, Z, F, G, H, P, T, V, etc., if applying control oil internal sup, please try to use external add enough back pressure on return port T( port Y shall not have back pressure) to ensure valves can reverse properly.
2. Pressure reducing valves shall be applied when control pressure exceeds 250bar.

Symbols

Detailed and simplified symbols for 3-position valves

                   Valves with spring centered                                    Valves with hydraulic centered

Valves with spring offset (At position A or B of 2-position valve derived from 3-position)

Valves with hydraulic offset (At position A or B of 2-position valve derived from 3-position)

Spools of 3-position valves

                       3-position valve 2-positon                                       derivative from 3-position

Detailed and simplified symbols for 2-position valves

Spools of 2-position valves

Technical details

1. Hydraulic section

1). WEH10 Type electro-hydraulic directional valve

2). WEH16 Type electro-hydraulic directional valve

3). WEH25 Type electro-hydraulic directional valve

4). WEH32 Type electro-hydraulic directional valve

*Switching time refers to time from drawing of solenoid of pilot valve to full opening of main valve.

2. Electrical data

1)Usually used for engineering machinery.

    For other voltage, please consult the company.