DE2433437C2 - Control system for a hydraulic crane - Google Patents

Description

κι

The invention relates to an electro-hydraulic control device according to the preamble of claim 1.

A known from practice electro-hydraulic control device of this type has a plurality of Control valves for the various actuators. There is a separate one for each control valve Auslaßveniileinrichtung provided with which the pump pressure to T;> nk is reduced if the associated Control valve is in its neutral position. The outlet valve devices can be activated electromagnetically Discharge valves assigned which, in an open position, cause the associated discharge valve devices reduce the pump pressure in the tank even if the associated control valve is being actuated will.

The drain valves or their actuating magnets are electrically connected to a load measuring device that moves them to the open position when a load limit is reached switches. The disadvantage is that for the plurality of Auslaßveniilcinrichtungcn and the drain valves only with the necessary hydraulic and electrical connections between the respective cooperating components can be produced. This structural effort can be reduced especially with im Realize space-limited mobile cranes with difficulty. In addition, the lines must be checked frequently and represent a latent source of disturbance, since they cause unavoidable wear and tear during operation of the construction crane subject. The electro-hydraulic control device provides a certain safety function, because when a laser limit is reached, the control valves are actuated again No parts are prevented from being monitored, but despite the Construction work does not exclude the possibility of the components monitored with regard to their load efficiency after neutralization their control valves still perform uncontrollable movements under the influence of a load. These are particularly dangerous if they exceed the load limit. This moment of danger results from the fact that the pilot valve pilot-controlled load holding valve when neutralizing the Control valves are or are still in its Oifensicllung can be brought into the open position. The actuator can then still move uncontrollably.

The invention is based on the technical problem a clcktro-hydraulic control device of the opening to create the type described, the low structural wall by Ncutralisierung the control valves the risk of exceeding the limit. and uncontrolled Own movements /. At least with regard to their Lasigren / e monitor actuating device prevented.

The task is determined by the features of claim 1 solved.

Several: 'Control valves to each of a group and /. assignment only one single μαι Auslal.KeMlilcinrichluii). · as well as a single Ab add to this (innppe cry there is an erhehlnhc

structural simplification without impairing the idling function for the control valves of the group Lt. The number of hydraulic and electrical lines required is also significantly reduced. These lines can be safely accommodated even when space is limited. As a result of that the load-holding valve is also included in the safety control circuit when the load limit is reached prevents further actuation of an actuator, it is ensured that after Neutralize the control valves from the pilot operated Actuating device monitored by the load holding valve does not perform any uncontrolled movements able because the load-holding valve in its Spcrrsiellung is brought and held in it.

Further refinements of the invention are contained in the subclaims. In the drawings is a Embodiment of the invention shown. In it shows

F i g. 1 is a side view of a truck crane with a control system,

F i g. 2 is a block diagram of the control system,

F i g. 3 is an enlarged plan view of an inlet-outlet part of a valve group;

F i g. 4 shows a side view of the part according to FIG. 3,

FIG. 5 is a view of the component according to FIG Line V-V according to FIG. 3,

F i g. 6 is an enlarged partial sectional view through a control valve;

F i g. 7 schematically shows a valve arrangement in a jo Operating position,

F i g. 8 valve arrangement according to FIG. 7 in a different operating position and

F i g. 9 shows a further operating position of the valve arrangement. J5

Fig. 1 shows a side view of an according to the invention Truck crane which has a chassis 10 on which front wheels 11, rear wheels 12, retractable booms 13. a driver's cab 14, an internal combustion engine 15 for driving the wheels and a crane attachment 16 nion 4η are animalized.

The crane attachment 16, which is on the chassis 10 with the help of a rotatable support device 17 in the horizontal is rotatable in both directions, has a supporting framework 19 on which a folded in the The telescopic boom 20 shown in the rest position is articulated, as well as two boom lifting cylinders 21 (from which only one in FIG. 1 can be seen), as actuating devices for raising and lowering of the boom, a main winch 22 and an auxiliary winch 23 for boom load ropes, not shown, an internal combustion engine 25 for driving two hydraulic pumps 26 and 37, a tank 27 for the hydraulic fluid, a crane operator's cab 28 and control levers 30 for a hydraulic control system shown schematically in FIG the F i g. 2 is shown. The crane attachment 16 is rotatable by means of a hydraulic motor 29 which is mounted on the framework 19 is attached.

The telescopic boom 20 consists of a base section 31, an inner middle section 32, an outer section outer middle section 33 and an outer section 34, which is equipped with a working head 35 is. at which z. B. a pulley 36 is rotatably mounted. The base section 31 of the boom 20 is on upper framework 19 by means of a bearing pin 40 t, 5 pivoted. The boom 20 is lifted by means of the extendable and retractable boom lift cylinders 21 raised and lowered, each of which is between the upper framework 19 and the base section 31 of the boom 20 is pivotably articulated by means of a bearing pin 41 or 42.

The boom sections 32,33 and 34 are by means of hydraulic Cylinders 45, 46 and 47, which are arranged within the hollow boom 20, are extendable and retractable. The winches 22 and 23 are driven by hydraulic motors 50 and 51, respectively.

As the F i g. 2 shows the crane attachment 16, boom 20, boom sections 32, 33 and 34 and the winches 22 and 23 moved or operated by means of hydraulic actuators, such as. B. from that Hydraulic motor 29, the boom lift cylinders 21, the hydraulic cylinders 45, 46 and 47 and the hydraulic motors 50 and 51, respectively. These actuating devices are in turn controlled by control valves operated by the driver or slide devices 81, 71, 72, 73, 74, 82 and 83 controlled, which the hydraulic fluid from the hydraulic pumps 26 and 37 to the actuators.

The F i g. 2 shows a schematic block diagram for the electro-hydraulic control system for the truck-mounted crane shown in FIG. The system closes the motor-driven hydraulic pumps 26 and 37, their liquid inlet connections via liquid lines 55 and 56 are connected to the tank 27, respectively. The liquid outlet connections or pressure connections of the Hydraulic pumps 26 and 37 are connected to the fluid inlet ports 59 via fluid lines 57 and 58, respectively and 60 of the inlet-outlet parts 61 and 62 of the control valve groups 63 and 64, respectively. The liquid outlet connections 65 and 66 of the valve groups 63 and 64 are connected via liquid return lines 67 and 68 connected to the tank 27.

The control valve rows 63 and 64, only in number the control valves or slide parts and the crane control functions carried out with them differ are, are mounted on the crane attachment 16, and the slide devices of the valve rows are via a Linkage 69 mechanically connected to the control levers 30 arranged in the crane operator's cab 28, (Fig. 1).

The valve 64 has an inlet-outlet part 62 and control valves 71, 72, 73 and 74 for controlling the extension stroke cylinders 21 of the cylinder 45 for the inner central section, the cylinder 46 for the outer central section and the cylinder 47 for the outer central section, respectively The cylinders are connected to the control valves via the fluid lines 71a-716, 72a- 72b, 73a-73b and 74a- 74b, respectively. A manually controllable valve 135 for two speed levels actuates a control valve 135a, through which the two sections 374 and 37ß of the torque divider pump 37 are to be connected in parallel to increase the operating speed of the boom lift cylinders 21 and / or the telescopic cylinders 45, 46, 47.

The valve group 63 has an inlet fitting 61 and three slide devices 81, 82 and 83, which are used to control the slewing motor 29 for the crane attachment 16, and to control the main winch motor 50 and the auxiliary winch motor 51, the motors to the slide devices via the liquid lines 81.-J-8I / 1. 82,7-826 or 83;) - 836 connected are.

Since the Kinlaß-Aiislaßtcilc and the pusher means of Stcuerventilgruppen 63 and 64 are substantially identical, only the inlet-outlet to the Steuervcntilgruppc the 64th in the f ⁱ g. 2. 3. 4, 5. 7. 8 and

9 and the sliding device 71 shown in FIG FIGS. 2 and 6 are shown in more detail below to be discribed.

In the F i g. 7, 8 and 9 it can be seen that the inlet-outlet part 62 has a valve chamber 112 in which there is a control pressure and in which a throttle bore 114 opens. The valve chamber also has a spring-loaded relief valve cone as Starting valve device 110, a ball-loaded bypass valve cone 180 and a spring-loaded pressure relief valve cone 182.

The relief valve kegcl UO serves to control the liquid wedge coming from the hydraulic pump 37 Discharge tank 27 when the control valves of the valve bank 64 are in their zero position (i.e. when the Liquid pressure in the Vcniiikkammer 112 is minimal). The bypass valve cone 180 controls the flow of liquid proportionally to the slide position so that the Liquid is directed to the tank 27 and to the control valves in the valve group 64. The pressure relief valve cone 182 is used for pressure relief, if the pin pressure exceeds a prescribed value.

The control pressure in the valve chamber 112 is derived from the fluid pressure of the hydraulic pump 37 and is applied to each control valve 71, 72, 73 and 74 of the valve row 64, and the fluid flow takes place in each control valve of the valve row 64 through the channels S 1 and S 2, as shown in FIG. 6 is shown. Each channel 52 of a control valve of the valve row 64 is connected to the channel 51 of the next adjacent, downstream control valve, and the channel 52 of the last control valve of the valve row 64 opens into the tank 27. Any movement of any control valve slide SP interrupts the flow of fluid from channel 51 to the Channel 5 2, and when this occurs, the control pressure in valve chamber 112 increases.

A more detailed explanation of the function of the valve cones arranged in the inlet-outlet part 62 of the valve groups 64 and the control valve slide is given at the end of this description. If one or more valve spools SP of the control valves 71, 72, 73 and 74 of the valve group 64 are actuated to carry out a control function (assuming that the throttle bore 114 is closed), a pressure signal occurs in the valve chamber 112 in the form of a pressure increase and the relief valve poppet 110 is either completely closed (as shown in FIG. 8) or partially closed (as shown in FIG. 9) in order to interrupt or reduce the discharge of the liquid to the tank 27.

The in the F i g. The system shown in FIG. 2 also has a load holding valve 116 for the boom lift cylinders. which is preferably mounted outside, however, on each boom lifting cylinder 21 and prevents unintentional movement of the boom, as well as a liquid-actuated pilot valve 118 for actuating the load-holding valve 116 Fluid line 122 connected to the lower end of the boom lift cylinder 21. The piston rod-side end of the cylinder 21 is b 7t connected via the liquid line 71 to the other end of the slider device. The pilot valve 118 is connected via a control pressure fluid line 126 to a fluid outlet of a pilot valve device 127, which is fed by a motor-driven auxiliary pump 128. The pilot valves 127 and 127a also direct the fluid to pilot valves, e.g. B. to pilot valves 129 which direct the liquid coming from the hoist pump 128 to the master and auxiliary winch brake cylinders 131. When the load holding valve 116 is closed. then it prevents an inflow or outflow of the liquid to or from the lower end of the boom lift cylinder 21. Therefore, when the boom 20 is in a raised position, it is in this position.

Ki treatment locked by closing the holding valve 116. The load holding valve 116 is dependent on the actuation of the pilot valve 118 actuated. When the control fluid is delivered to the pilot valve 118, then moves the load-holding valve 116 is in its open position.

Γι If therefore the control fluid from the pilot valve ■ IS is derived, then the Piiotventii closes that Load holding valve 116.

According to a further feature of the invention, the FIG. 2 is an electro-hydraulic control system Device to switch off the control valves, the slide devices of the control valve groups 63 and 64 is used and the load-holding valve 116 for the boom lift cylinder in the closed position holds when the boom is exposed to abnormal operating conditions. The electro-hydraulic device has a sensor device for detecting the Auslegcrstatuses, the z. B. from a conventional Load measuring device 104 may be formed for detecting an abnormal boom condition on the

jo crane is attached and depending on the boom condition emits a signal by which a plurality of drain valves 100, 101 and 102 are actuated at the same time. The load measuring device 104 consists, for. B. from a known electrical device based on the

j) crane is mounted and z. B. the relationship between the Boom angle and the load hanging on the boom detected. It opens a normally closed one electrical switch 150 when the boom is the safety limit or the prescribed operating limits exceeds. The load measuring device 104 switches the drain valves 100.101 and 102 via an electrical one Relay 160.

Each drain valve 100, 101 and 102 is known per se and operates in such a way that the two-way valve is opened

v, is. when the electrical coil of the solenoid valve is de-energized, as shown in FIG. 2 is shown. Energization of the coil causes the valve to close, thereby preventing fluid passage through the valve.

as shown in Figs. 2, 3, 4, 5, 7, 8 and 9, each is Valve group 63 and 64 equipped with a throttle bore 114, which is normally used to measure the control pressure is used in the valve group. When the throttle bore 114 is open. then it works itself setting pressure drop an actuation of the outlet 'valve device 110 in the corresponding valve group 63 or 64.

The drain valves 100 and 101 serve to switch off the valve slide devices of the valve groups 63

bo or 64. The drain valve 102 is used to lock the load holding valve 116 for the boom lift cylinder. More precisely, the drain valves 100 and 101 cause an opening of the exhaust valve devices 110, which are in the Inlet-outlet parts 61 and 62 of the valve groups 63 and 64 are arranged, and thus guide the otherwise the control valves from existing liquid. so that any subsequent control valve movement is prevented and with it any movement of the crane parts.

An actuation of the drain valves 100 and 101 causes the liquid flow to be diverted from the Sieiierdruekkammer even when one or more slide valves require liquid and, on the other hand, a control signal for a maximum pressure is generated in the valve 112 so that the outlet valve device HO opens and the Slider devices become ineffective. The drain valve 102 passes on the other hand to prevent the liquid coming to Auslegerhubzylinders Lasthaltevcntil 116 to close this and to provide a pressure relief or open the load holding valve 1 16, and an inadvertent movement of the boom 20 from the pilot valve 118th

If one or more valve slide devices SP are to exercise a control function in one or the other valve group, the pressure signal in the valve chamber 112 rises and the outlet valve device 110 closes in order to interrupt or at least reduce the discharge of the liquid / around the reservoir 27. In contrast, if one or more valve slides are actuated and the throttle holes 114 of the valve groups 63 and 64 is opened as a result of Auslegerbewcgung, then 1 12, the same effect is achieved by the pressure drop in the valve chamber as if no signal conditioning and then opens the exhaust valve 110 to directing the liquid from pumps 26 and 37 to tank 27 instead of valve groups 63 and 64 .

For safety reasons, the valve of each drain valve 100, 101 and 102 is arranged in a liquid line between the corresponding control valve and the tank 27 and is held in its closed position by the excitation of the coil of the drain valve. De-energization of the solenoid coil as a result of an incorrect signal emitted by load measuring device 104 (which opens switch 150 ) or an electrical fault de-energizes the control valve group or the boom lift cylinder holding valve controlled by the solenoid valve.

The load measuring device 104 responds. when the crane boom 20 exceeds a certain operating range or a safety limit to open a normally closed electrical switch 150 . As the F i g. 2 shows, the switch 150 is connected to a connection via a main on-off switch 151 (which is preferably connected to the ignition switch of the engine 25 ) to a connection of a power source, such as e.g. B. a battery 152 is connected, the other terminal of which is connected to the vehicle ground 153 . The other terminal of the switch 150 is connected to a relay terminal 1 of a relay device 160 through a pair of normally open limit switches 155 and 156 connected in series. The relay device has a relay coil 161 which switches a set of normally closed relay contacts 162 and a set of normally open relay contacts 163. The relay coil 161 is connected to a relay terminal 5, which is connected to the vehicle ground 153, and also to a relay terminal 4, which in turn is connected via a conductor 164 to a branch point 166 between the switches 150 and 155. A conductor 167 connects the relay connection t to a branch point 168 between the switches 150 and 151. The relay device 160 is further equipped with relay connections 2 and 3, which have the following connections . The relay terminal 2 is connected to one side of a normally closed relay contact 162 , which in turn is connected to the RcliiisanschliiU 1. The other side of the Kelais connection 2 is connected to the carriage 153 via a signal light 170 . The ReluisanschluU 3 is ^r 'is a ropes to one side of the normally open Relaiskoniakles 163 angeschlossen.dessen other side to the relay terminal 1 is connected. The relay terminal 3 is also connected via a conductor 172 to a terminal of each of the solenoid valve spools 100a, 101a and 102a

H) of the drain valves 100, 101 and 102 , respectively.

Assuming that the main switch 151 is closed (on set) and that the switch 150 is also normally closed when the boom is in an allowable position, the relay coil 161 is energized and causes the relay contacts 163 to close and open relay contacts 162. When relay contacts 163 are closed, power can flow from battery 152 through main switch 151, through conductor 167, through closed contacts 163, and through each solenoid 100a, 101a and 102a to energize them and cause their magnetic drain valves 100, 101 and 102 to close, respectively. In this state, the signal light 170 does not light up. and limit switches 155 and 156 are open. When the drain valves 100, 101 and 102 close, then all the control valves of the valve groups 63 and 64 are in their operating position, and the pilot valve 118 directs the liquid to the open holding valve 116 , that is to say that the boom lift cylinder 21 is actuated by the control valve 71 operating fluid is fed and discharged in both directions.

If the load measuring device 104 responds because the boom 20 exceeds the operating limit, then the switch 150 , which responds to an error signal, is opened. By opening the switch 150 , the relay coil 161 is de-energized, which in turn causes the relay contacts 163 to open and the relay contacts 162 to close. When the relay contacts 163 are open, the solenoids 100a, Wi α and 102a are de-energized, and the drain valves 100, 101 and 102 are moved to their open position. When relay contacts 162 close, current flows from battery 152 through switch 151, through conductor 167.

through the contacts 162 and through the signal light 170, which then lights up and emits a warning signal. When the drain valves 100 and 101 open, the valve groups 63 and 64 become ineffective because the liquid is diverted away from them in the manner described above. When the discharge valve 102 opens, then the valve 118 from the pilot 7u the load holding valves 116 flowing liquid is drained and the hold valves are closed. If the valve groups 63 and 64 are ineffective sam , then an actuation of any control valve in one of the two rows of valves causes no control function, so that the components of the crane remain immobile. When the load holding valves 116 are closed, the boom lift cylinders 21 can neither be extended nor retracted.

In order to bypass the open switch 150 responsive to a fault, the normally open limit switches 155 and 156 are necessary to close both by hand. Then, a current flows from the battery 152 through the main switch 151 through the Conductor 167, through relay terminal 1, through limit switches 156 and 155, through conductor 164 and through relay coil 161 to vehicle ground 153. This energizes relay coil 161, which in turn

the solenoids 100a, 101a and 102a are excited in the manner described above, so that the results already described are achieved. The closing of the drain valves 100, 101 and 102 causes the valve groups 63 and 64 to respond again, and the pilot valve 118 again conveys liquid to the load-holding valves 116 in order to open them. This means that the crane parts can be brought back within the desired operating limits.

The function of the valve groups is described below. As has already been stated, the valve group 64 has a combined inlet-outlet part 62 and a plurality of control valves 71, 72, 73 and 74 which are arranged laterally next to the inlet-outlet part. The liquid inlet and outlet connections 60 and 66 (pressure connections or tare connections) are combined in the inlet part. As the F i g. 7, 8 and 9 show, the inlet part 62 has a relief valve cone as the outlet valve device 110, which directs the liquid coming from the pump 26 or 37 directly to the tank 27 when the slide devices are in the zero position. The inlet-outlet part 62 also has a bypass valve cone 180 which, depending on the slide position, directs the liquid flow proportionally to the tank 27 and to the slide devices. The inlet-outlet portion 62 also has a main relief valve poppet 182 . Finally, the inlet-outlet part 62 is equipped with a valve chamber 112 in which there is a control pressure. The control pressure is generated by the pump pressure and is applied to each control valve. The fluid having the control pressure flows through the channels 51 and S 2, which are arranged in each individual control valve slide SP. Each channel 52 of a valve slide is connected to channel S1 of an adjoining valve slide, and channel 52 of the last valve slide opens into tank 27. Any movement of any valve slide interrupts the flow from channel 1 to channel 2, thereby increasing the signal pressure through a hole in the valve chamber 112 of the inlet-outlet part 62 transmitted.

As shown in FIGS. 7, 8 and 9 can be seen, the arranged in the inlet-outlet part 62 relief valve cone has a relatively large area unsupported Excess liquid flow off into the reservoir 27. When the control pressure in the valve chamber 112 the closing force of the main overpressure valve cone 182 during the function of the bypass valve cone 180 exceeds, then this opens and relieves the control pressure in the valve chamber 112, so that the relief valve cone 110 can open and can divert the pump pressure to the reservoir 27 (FIG. 9). This results in a state of equilibrium in which

ίο enough liquid from the pump into the reservoir 27 can escape and with any pressure relief valve setting an outlet pressure is maintained.

In FIG. 6 shows a typical slide device 71 in which the liquid coming from the pump enters channel F. The pump pressure is constantly applied and is detected via the hole PX at the left end of the floating compensating slide CP. When the main valve spool SP is in its neutral position, the pump pressure in channel P is absorbed by the compensating valve part at the left end of the compensating valve CP , and since there is no compensating pressure at the right spring end of the compensating valve, the pressure from the pump

2 ·) pe incoming liquid flow move the equalizing valve CP to the side, so that the liquid flows through the Channel Γ can flow through, which is connected to the channel P of the next slide device. When the main valve spool 5P moves to the left

JO moves away, then several processes take place at the same time. First, the flow of the control fluid through the channels 51 and 52 is interrupted. Then the Pump flow is directed from the inlet-outlet part 62 through the channel P into the slide device 71.

Then the control grooves of the central web of the main valve slide SP move out of their rest position and allow the liquid to enter the region P1 through the channel P. The liquid then flows through the load holding valve and into section C2. which lies behind the adjacent control web CL , which is now open as a result of the leftward movement of the main valve slide. The liquid in section Cl is then due to the simultaneous movement of the corresponding

tcrdisted between that surface. which derives its own control web 45 into the reservoir 27, is exposed to pressure in the chamber 112, and as shown in FIG. 6 can be seen, is through the

The area exposed to the pump pressure in the chamber P. When a pressure signal occurs in the valve chamber 112, the relief valve cone 110 closes as a result (FIG. 8). As a result, the liquid flow coming from the pump is directed through the inlet-outlet part 62 to the control valves 71 and 74, flows through the channels S 1 and 52 of each slide device that is in its neutral position to one or more other slide devices that are not are in the neutral position and require a flow of liquid to perform a function.
When the flow of liquid generated by the pump

greater than that caused by all slide devices together.

Control groove of the central control web for each working position of the valve spool SP produces an opening for the flow of liquid. The main liquid flow passing through this opening creates a pressure drop, so that the pressure in the channel Pl is smaller than the pressure in the channel P. The pressure in the channel P1 acts on the spring end of the compensating slide CP and increases the spring force D, so that the compensating slide CP assumes a state of equilibrium with respect to the pressure force acting in the chamber P at the left end and a throttling of the liquid flowing in the direction from the channel P to the channel F

is the required flow of liquid. the ratio of the area of the bypass valve, which is the pump pressure in the chamber Pausgcseizt, and that area, which is exposed to the control pressure in the valve chamber 112 , is relatively small. As a result, the bypass valve poppet 180 takes its equilibrium position due to the pressure in the chamber P and in the chamber. in the Fi g. 8 is shown. The spring force of the spring D is constant. Therefore, the pressure difference between the channels P1 and P is constant and thus the pressure difference for the assumed valve slide position at all pressure values in the chamber P. Therefore, for each fixed cross-sectional opening for the liquid flow, this is also constant if the pressure difference is constant. Therefore any control function remains,

11th

which takes place via the channel Cl, regardless of changes in load or required pressure (which is connected to the line b 71) unchanged.

When the valve slide SP moves, the size of the control opening of the central control web changes, but the floating compensating slide CP does not respond to this. The compensating valve CP senses pressure changes in the chamber P and in the channel PI and shifts to compensate for these pressure changes. This results in the pressure differential being held at a fixed predetermined value regardless of changes in the direction of flow. The compensating slide CP also responds to flow conditions prevailing downstream with higher or lower pressures than the pressures prevailing in itself and shifts accordingly in order to enable the required flow of liquid to the downstream slide devices.

In addition 5 sheets of drawings

J (I

J ^r >

50

55

bO

b5

Claims (4)

Patent claims: 1. Elekiro-hydraulic control device, in particular for a truck crane, with several by at least one hydraulic actuator movable components, of which at least one wc by a load measuring device with regard to a load limit is monitored, with a large number of can be acted upon by a pump arrangement, Optionally operable control valves for the actuating devices, with when not actuated of the control valves, the discharge valve devices for the Control valves with magnetically actuated and with the load measuring device in switching connection Drain valves for the exhaust valve devices, which are canceled when a load limit is reached are switchable in which the Ausiaßventilcinriehtungen the pressurization for the control valves regardless of an actuation of the control valves prevent, and associated with at least one of the load-limited actuating device Load holding valve which is piloted in this way by a pilot valve. that it depends on the activity at least one control valve can be brought into a blocking position and the actuating device hydraulically blocked, characterized in, that the control valves are combined in separate groups (63, 64) which can be acted upon in parallel by pressure medium; that each Control valve group (63,64) an outlet valve device common to all control valves of the group (110) and one associated with the outlet valve device (I10) Drain valve (100, 101) is assigned, and that the load-holding valve (116) vorstcucrseilig another, electromagnetically operable and parallel to the drain valve (100, 101) of the control valve groups is associated with the L; sstmcßeinrichiiing (l04) connected drain valve (102). with the when the load limit / .e is reached, the l.asihalieveniil (116) can be switched to its locking position. 2. Electrohydraulic control device according to claim 1, characterized in that the l.ustmcßcinrichmng (104) with a magnetic actuation of the drain valves (100, 101, 102) on the Reaching the load limit electrically responsive device (160) is connected. 3. Electro-hydraulic control device according to claims I and 2, characterized in that that two control valve groups (63, 64) are provided for groups of actuators, that a separate pump for each control valve group and for the pilot control of the load holding valve (116) (26, 37, 128) is provided, the pump (128) being connected to a pilot valve device (127, 127, · ^ is. the VorMcucrdruck depending on the actuation of at least one control valve to the pilot valve (118) for the load holding valve (116). 4. Electro-hydraulic control device according to claims 1 to 3. wherein one component is a crane boom is. who by at least one a vorsieuerb.ires L. is holding valve exhibiting loan and Lowering operation unit is movable. through this marked, dall two working in parallel and in each case a condensation valve (116) instructing the outlet valve (116) j-'ungsetnrichmngcn (21) are provided that the Load holding valves (116) connected in parallel to a pilot control line connected to the Pilctventil (118) are, and that the further drain valve (102) is arranged in the pilot control line and with the Tank (27) is connected.